diff --git a/bin/dartdoc.dart b/bin/dartdoc.dart
index eaa0b4a284..f73248a22a 100644
--- a/bin/dartdoc.dart
+++ b/bin/dartdoc.dart
@@ -17,7 +17,7 @@ Future<void> main(List<String> arguments) async {
     // There was an error while parsing options.
     return;
   }
-  final packageBuilder = PubPackageBuilder(config);
+  final packageBuilder = PubPackageBuilder(config, pubPackageMetaProvider);
   final dartdoc = config.generateDocs
       ? await Dartdoc.fromContext(config, packageBuilder)
       : await Dartdoc.withEmptyGenerator(config, packageBuilder);
diff --git a/lib/dartdoc.dart b/lib/dartdoc.dart
index 1b513e3500..016304fedb 100644
--- a/lib/dartdoc.dart
+++ b/lib/dartdoc.dart
@@ -10,8 +10,9 @@ library dartdoc;
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:io';
+import 'dart:io' show exitCode, stderr;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/generator/empty_generator.dart';
 import 'package:dartdoc/src/generator/generator.dart';
@@ -41,17 +42,19 @@ const String dartdocVersion = packageVersion;
 /// Helper class that consolidates option contexts for instantiating generators.
 class DartdocGeneratorOptionContext extends DartdocOptionContext
     with GeneratorContext {
-  DartdocGeneratorOptionContext(DartdocOptionSet optionSet, Directory dir)
-      : super(optionSet, dir);
+  DartdocGeneratorOptionContext(
+      DartdocOptionSet optionSet, Folder dir, ResourceProvider resourceProvider)
+      : super(optionSet, dir, resourceProvider);
 }
 
 class DartdocFileWriter implements FileWriter {
   final String outputDir;
+  ResourceProvider resourceProvider;
   final Map<String, Warnable> _fileElementMap = {};
   @override
   final Set<String> writtenFiles = {};
 
-  DartdocFileWriter(this.outputDir);
+  DartdocFileWriter(this.outputDir, this.resourceProvider);
 
   @override
   void write(String filePath, Object content,
@@ -73,10 +76,11 @@ class DartdocFileWriter implements FileWriter {
     }
     _fileElementMap[outFile] = element;
 
-    var file = File(path.join(outputDir, outFile));
+    var file = resourceProvider
+        .getFile(resourceProvider.pathContext.join(outputDir, outFile));
     var parent = file.parent;
-    if (!parent.existsSync()) {
-      parent.createSync(recursive: true);
+    if (!parent.exists) {
+      parent.create();
     }
 
     if (content is String) {
@@ -100,14 +104,16 @@ class Dartdoc {
   final PackageBuilder packageBuilder;
   final DartdocOptionContext config;
   final Set<String> writtenFiles = {};
-  Directory outputDir;
+  Folder outputDir;
 
   // Fires when the self checks make progress.
   final StreamController<String> _onCheckProgress =
       StreamController(sync: true);
 
   Dartdoc._(this.config, this.generator, this.packageBuilder) {
-    outputDir = Directory(config.output)..createSync(recursive: true);
+    outputDir = config.resourceProvider
+        .getFolder(config.resourceProvider.pathContext.absolute(config.output))
+          ..create();
   }
 
   /// An asynchronous factory method that builds Dartdoc's file writers
@@ -182,9 +188,9 @@ class Dartdoc {
     final generator = this.generator;
     if (generator != null) {
       // Create the out directory.
-      if (!outputDir.existsSync()) outputDir.createSync(recursive: true);
+      if (!outputDir.exists) outputDir.create();
 
-      var writer = DartdocFileWriter(outputDir.path);
+      var writer = DartdocFileWriter(outputDir.path, config.resourceProvider);
       await generator.generate(packageGraph, writer);
 
       writtenFiles.addAll(writer.writtenFiles);
@@ -225,15 +231,16 @@ class Dartdoc {
         throw DartdocFailure(
             'dartdoc encountered $errorCount errors while processing.');
       }
-      logInfo(
-          'Success! Docs generated into ${dartdocResults.outDir.absolute.path}');
+      var outDirPath = config.resourceProvider.pathContext
+          .absolute(dartdocResults.outDir.path);
+      logInfo('Success! Docs generated into $outDirPath');
       return dartdocResults;
     } finally {
       // Clear out any cached tool snapshots and temporary directories.
       // ignore: unawaited_futures
-      SnapshotCache.instance.dispose();
+      SnapshotCache.instance?.dispose();
       // ignore: unawaited_futures
-      ToolTempFileTracker.instance.dispose();
+      ToolTempFileTracker.instance?.dispose();
     }
   }
 
@@ -289,35 +296,43 @@ class Dartdoc {
     var staticAssets = path.joinAll([normalOrigin, 'static-assets', '']);
     var indexJson = path.joinAll([normalOrigin, 'index.json']);
     var foundIndexJson = false;
-    for (var f in Directory(normalOrigin).listSync(recursive: true)) {
-      if (f is Directory) {
-        continue;
-      }
-      var fullPath = path.normalize(f.path);
-      if (fullPath.startsWith(staticAssets)) {
-        continue;
-      }
-      if (fullPath == indexJson) {
-        foundIndexJson = true;
-        _onCheckProgress.add(fullPath);
-        continue;
-      }
-      if (visited.contains(fullPath)) continue;
-      var relativeFullPath = path.relative(fullPath, from: normalOrigin);
-      if (!writtenFiles.contains(relativeFullPath)) {
-        // This isn't a file we wrote (this time); don't claim we did.
-        _warn(packageGraph, PackageWarning.unknownFile, fullPath, normalOrigin);
-      } else {
-        // Error messages are orphaned by design and do not appear in the search
-        // index.
-        if (<String>['__404error.html', 'categories.json'].contains(fullPath)) {
-          _warn(packageGraph, PackageWarning.orphanedFile, fullPath,
-              normalOrigin);
+
+    void checkDirectory(Folder dir) {
+      for (var f in dir.getChildren()) {
+        if (f is Folder) {
+          checkDirectory(f);
+          continue;
+        }
+        var fullPath = path.normalize(f.path);
+        if (fullPath.startsWith(staticAssets)) {
+          continue;
         }
+        if (path.equals(fullPath, indexJson)) {
+          foundIndexJson = true;
+          _onCheckProgress.add(fullPath);
+          continue;
+        }
+        if (visited.contains(fullPath)) continue;
+        var relativeFullPath = path.relative(fullPath, from: normalOrigin);
+        if (!writtenFiles.contains(relativeFullPath)) {
+          // This isn't a file we wrote (this time); don't claim we did.
+          _warn(
+              packageGraph, PackageWarning.unknownFile, fullPath, normalOrigin);
+        } else {
+          // Error messages are orphaned by design and do not appear in the search
+          // index.
+          if (<String>['__404error.html', 'categories.json']
+              .contains(fullPath)) {
+            _warn(packageGraph, PackageWarning.orphanedFile, fullPath,
+                normalOrigin);
+          }
+        }
+        _onCheckProgress.add(fullPath);
       }
-      _onCheckProgress.add(fullPath);
     }
 
+    checkDirectory(config.resourceProvider.getFolder(normalOrigin));
+
     if (!foundIndexJson) {
       _warn(packageGraph, PackageWarning.brokenLink, indexJson, normalOrigin);
       _onCheckProgress.add(indexJson);
@@ -327,8 +342,8 @@ class Dartdoc {
   // This is extracted to save memory during the check; be careful not to hang
   // on to anything referencing the full file and doc tree.
   Tuple2<Iterable<String>, String> _getStringLinksAndHref(String fullPath) {
-    var file = File('$fullPath');
-    if (!file.existsSync()) {
+    var file = config.resourceProvider.getFile('$fullPath');
+    if (!file.exists) {
       return null;
     }
     // TODO(srawlins): It is possible that instantiating an HtmlParser using
@@ -353,8 +368,8 @@ class Dartdoc {
       PackageGraph packageGraph, String origin, Set<String> visited) {
     var fullPath = path.joinAll([origin, 'index.json']);
     var indexPath = path.joinAll([origin, 'index.html']);
-    var file = File('$fullPath');
-    if (!file.existsSync()) {
+    var file = config.resourceProvider.getFile('$fullPath');
+    if (!file.exists) {
       return null;
     }
     var decoder = JsonDecoder();
@@ -519,7 +534,7 @@ class DartdocFailure {
 class DartdocResults {
   final PackageMeta packageMeta;
   final PackageGraph packageGraph;
-  final Directory outDir;
+  final Folder outDir;
 
   DartdocResults(this.packageMeta, this.packageGraph, this.outDir);
 }
diff --git a/lib/options.dart b/lib/options.dart
index 8c833276c0..50686f214a 100644
--- a/lib/options.dart
+++ b/lib/options.dart
@@ -1,29 +1,34 @@
 import 'dart:async';
-import 'dart:io';
+import 'dart:io' show stderr, exitCode;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:args/args.dart';
 import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/logging.dart';
 
 class DartdocProgramOptionContext extends DartdocGeneratorOptionContext
     with LoggingContext {
-  DartdocProgramOptionContext(DartdocOptionSet optionSet, Directory dir)
-      : super(optionSet, dir);
+  DartdocProgramOptionContext(
+      DartdocOptionSet optionSet, Folder dir, ResourceProvider resourceProvider)
+      : super(optionSet, dir, resourceProvider);
 
   bool get generateDocs => optionSet['generateDocs'].valueAt(context);
   bool get help => optionSet['help'].valueAt(context);
   bool get version => optionSet['version'].valueAt(context);
 }
 
-Future<List<DartdocOption<bool>>> createDartdocProgramOptions() async {
+Future<List<DartdocOption<bool>>> createDartdocProgramOptions(
+    PackageMetaProvider packageMetaProvider) async {
+  var resourceProvider = packageMetaProvider.resourceProvider;
   return [
-    DartdocOptionArgOnly<bool>('generateDocs', true,
+    DartdocOptionArgOnly<bool>('generateDocs', true, resourceProvider,
         help:
-            'Generate docs into the output directory (or only display warnings if false).',
+            'Generate docs into the output directory (or only display warnings '
+            'if false).',
         negatable: true),
-    DartdocOptionArgOnly<bool>('help', false,
+    DartdocOptionArgOnly<bool>('help', false, resourceProvider,
         abbr: 'h', help: 'Show command help.', negatable: false),
-    DartdocOptionArgOnly<bool>('version', false,
+    DartdocOptionArgOnly<bool>('version', false, resourceProvider,
         help: 'Display the version for $programName.', negatable: false),
   ];
 }
@@ -33,13 +38,16 @@ Future<DartdocProgramOptionContext> parseOptions(
   List<String> arguments, {
   OptionGenerator additionalOptions,
 }) async {
-  var optionSet = await DartdocOptionSet.fromOptionGenerators('dartdoc', [
-    () => createDartdocOptions(packageMetaProvider),
-    createDartdocProgramOptions,
-    createLoggingOptions,
-    createGeneratorOptions,
-    if (additionalOptions != null) additionalOptions,
-  ]);
+  var optionSet = await DartdocOptionSet.fromOptionGenerators(
+      'dartdoc',
+      [
+        createDartdocOptions,
+        createDartdocProgramOptions,
+        createLoggingOptions,
+        createGeneratorOptions,
+        if (additionalOptions != null) additionalOptions,
+      ],
+      packageMetaProvider);
 
   try {
     optionSet.parseArguments(arguments);
@@ -51,12 +59,12 @@ Future<DartdocProgramOptionContext> parseOptions(
     exitCode = 64;
     return null;
   }
-  if (optionSet['help'].valueAt(Directory.current)) {
+  if (optionSet['help'].valueAtCurrent()) {
     _printHelp(optionSet.argParser);
     exitCode = 0;
     return null;
   }
-  if (optionSet['version'].valueAt(Directory.current)) {
+  if (optionSet['version'].valueAtCurrent()) {
     _printVersion(optionSet.argParser);
     exitCode = 0;
     return null;
@@ -64,7 +72,8 @@ Future<DartdocProgramOptionContext> parseOptions(
 
   DartdocProgramOptionContext config;
   try {
-    config = DartdocProgramOptionContext(optionSet, null);
+    config = DartdocProgramOptionContext(
+        optionSet, null, packageMetaProvider.resourceProvider);
   } on DartdocOptionError catch (e) {
     stderr.writeln(' fatal error: ${e.message}');
     stderr.writeln('');
diff --git a/lib/src/dartdoc_options.dart b/lib/src/dartdoc_options.dart
index 523f3b68ee..a2e07cc8fd 100644
--- a/lib/src/dartdoc_options.dart
+++ b/lib/src/dartdoc_options.dart
@@ -15,9 +15,10 @@
 library dartdoc.dartdoc_options;
 
 import 'dart:async';
-import 'dart:io';
+import 'dart:io' show Platform;
 
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:args/args.dart';
 import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/experiment_options.dart';
@@ -26,7 +27,7 @@ import 'package:dartdoc/src/source_linker.dart';
 import 'package:dartdoc/src/tool_runner.dart';
 import 'package:dartdoc/src/tuple.dart';
 import 'package:dartdoc/src/warnings.dart';
-import 'package:path/path.dart' as p;
+import 'package:path/path.dart' as p show Context, canonicalize, extension;
 import 'package:yaml/yaml.dart';
 
 /// Constants to help with type checking, because T is int and so forth
@@ -38,10 +39,7 @@ const int _kIntVal = 0;
 const double _kDoubleVal = 0.0;
 const bool _kBoolVal = true;
 
-/// Args are computed relative to the current directory at the time the
-/// program starts.
-final Directory directoryCurrent = Directory.current;
-final String directoryCurrentPath = p.canonicalize(Directory.current.path);
+typedef ConvertYamlToType<T> = T Function(YamlMap, String, ResourceProvider);
 
 class DartdocOptionError extends DartdocFailure {
   DartdocOptionError(String details) : super(details);
@@ -83,8 +81,8 @@ class CategoryConfiguration {
     return CategoryConfiguration._({});
   }
 
-  static CategoryConfiguration fromYamlMap(
-      YamlMap yamlMap, p.Context pathContext) {
+  static CategoryConfiguration fromYamlMap(YamlMap yamlMap,
+      String canonicalYamlPath, ResourceProvider resourceProvider) {
     var newCategoryDefinitions = <String, CategoryDefinition>{};
     for (var entry in yamlMap.entries) {
       var name = entry.key.toString();
@@ -95,9 +93,10 @@ class CategoryConfiguration {
         displayName = categoryMap['displayName']?.toString();
         documentationMarkdown = categoryMap['markdown']?.toString();
         if (documentationMarkdown != null) {
-          documentationMarkdown =
-              pathContext.canonicalize(documentationMarkdown);
-          if (!File(documentationMarkdown).existsSync()) {
+          documentationMarkdown = resourceProvider.pathContext.canonicalize(
+              resourceProvider.pathContext
+                  .join(canonicalYamlPath, documentationMarkdown));
+          if (!resourceProvider.getFile(documentationMarkdown).exists) {
             throw DartdocFileMissing(
                 'In categories definition for ${name}, "markdown" resolves to '
                 'the missing file $documentationMarkdown');
@@ -143,12 +142,16 @@ class ToolDefinition {
   /// Creates a ToolDefinition or subclass that is appropriate for the command
   /// given.
   factory ToolDefinition.fromCommand(
-      List<String> command, List<String> setupCommand, String description) {
+      List<String> command,
+      List<String> setupCommand,
+      String description,
+      ResourceProvider resourceProvider) {
     assert(command != null);
     assert(command.isNotEmpty);
     assert(description != null);
     if (isDartExecutable(command[0])) {
-      return DartToolDefinition(command, setupCommand, description);
+      return DartToolDefinition(
+          command, setupCommand, description, resourceProvider);
     } else {
       return ToolDefinition(command, setupCommand, description);
     }
@@ -190,17 +193,21 @@ class ToolDefinition {
 class Snapshot {
   File _snapshotFile;
 
+  // TODO(srawlins): Deprecate this public getter; change private field to just
+  // be the absolute path.
   File get snapshotFile => _snapshotFile;
   final Completer<void> _snapshotCompleter = Completer();
 
-  Snapshot(Directory snapshotCache, String toolPath, int serial) {
+  Snapshot(Folder snapshotCache, String toolPath, int serial,
+      ResourceProvider resourceProvider) {
     if (toolPath.endsWith('.snapshot')) {
       _needsSnapshot = false;
-      _snapshotFile = File(toolPath);
+      _snapshotFile = resourceProvider.getFile(toolPath);
       snapshotCompleted();
     } else {
-      _snapshotFile =
-          File(p.join(snapshotCache.absolute.path, 'snapshot_$serial'));
+      _snapshotFile = resourceProvider.getFile(resourceProvider.pathContext
+          .join(resourceProvider.pathContext.absolute(snapshotCache.path),
+              'snapshot_$serial'));
     }
   }
 
@@ -227,32 +234,35 @@ class Snapshot {
 class SnapshotCache {
   static SnapshotCache _instance;
 
-  Directory snapshotCache;
+  // TODO(srawlins): Make this final.
+  Folder snapshotCache;
+  final ResourceProvider _resourceProvider;
   final Map<String, Snapshot> snapshots = {};
   int _serial = 0;
 
-  SnapshotCache._()
+  SnapshotCache._(this._resourceProvider)
       : snapshotCache =
-            Directory.systemTemp.createTempSync('dartdoc_snapshot_cache_');
+            _resourceProvider.createSystemTemp('dartdoc_snapshot_cache_');
 
-  static SnapshotCache get instance {
-    _instance ??= SnapshotCache._();
-    return _instance;
-  }
+  static SnapshotCache get instance => _instance;
+
+  static SnapshotCache createInstance(ResourceProvider resourceProvider) =>
+      _instance ??= SnapshotCache._(resourceProvider);
 
   Snapshot getSnapshot(String toolPath) {
     if (snapshots.containsKey(toolPath)) {
       return snapshots[toolPath];
     }
-    snapshots[toolPath] = Snapshot(snapshotCache, toolPath, _serial);
+    snapshots[toolPath] =
+        Snapshot(snapshotCache, toolPath, _serial, _resourceProvider);
     _serial++;
     return snapshots[toolPath];
   }
 
-  Future<void> dispose() {
+  void dispose() {
     _instance = null;
-    if (snapshotCache != null && snapshotCache.existsSync()) {
-      return snapshotCache.delete(recursive: true);
+    if (snapshotCache != null && snapshotCache.exists) {
+      return snapshotCache.delete();
     }
     return null;
   }
@@ -260,6 +270,8 @@ class SnapshotCache {
 
 /// A special kind of tool definition for Dart commands.
 class DartToolDefinition extends ToolDefinition {
+  final ResourceProvider _resourceProvider;
+
   /// Takes a list of args to modify, and returns the name of the executable
   /// to run. If no snapshot file existed, then create one and modify the args
   /// so that if they are executed with dart, will result in the snapshot being
@@ -269,25 +281,26 @@ class DartToolDefinition extends ToolDefinition {
     assert(args[0] == command.first);
     // Set up flags to create a new snapshot, if needed, and use the first run
     // as the training run.
+    SnapshotCache.createInstance(_resourceProvider);
     var snapshot = SnapshotCache.instance.getSnapshot(command.first);
     var snapshotFile = snapshot.snapshotFile;
     var needsSnapshot = snapshot.needsSnapshot;
     if (needsSnapshot) {
       args.insertAll(0, [
-        '--snapshot=${snapshotFile.absolute.path}',
+        '--snapshot=${_resourceProvider.pathContext.absolute(snapshotFile.path)}',
         '--snapshot_kind=app-jit'
       ]);
     } else {
       await snapshot.snapshotValid();
       // replace the first argument with the path to the snapshot.
-      args[0] = snapshotFile.absolute.path;
+      args[0] = _resourceProvider.pathContext.absolute(snapshotFile.path);
     }
-    return Tuple2(Platform.resolvedExecutable,
+    return Tuple2(_resourceProvider.resolvedExecutable,
         needsSnapshot ? snapshot.snapshotCompleted : null);
   }
 
-  DartToolDefinition(
-      List<String> command, List<String> setupCommand, String description)
+  DartToolDefinition(List<String> command, List<String> setupCommand,
+      String description, this._resourceProvider)
       : super(command, setupCommand, description);
 }
 
@@ -295,19 +308,23 @@ class DartToolDefinition extends ToolDefinition {
 class ToolConfiguration {
   final Map<String, ToolDefinition> tools;
 
+  final ResourceProvider resourceProvider;
+
   ToolRunner _runner;
 
   ToolRunner get runner => _runner ??= ToolRunner(this);
 
-  ToolConfiguration._(this.tools);
+  ToolConfiguration._(this.tools, this.resourceProvider);
 
-  static ToolConfiguration get empty {
-    return ToolConfiguration._({});
+  static ToolConfiguration empty(ResourceProvider resourceProvider) {
+    return ToolConfiguration._({}, resourceProvider);
   }
 
   // TODO(jcollins-g): consider caching these.
-  static ToolConfiguration fromYamlMap(YamlMap yamlMap, p.Context pathContext) {
+  static ToolConfiguration fromYamlMap(YamlMap yamlMap,
+      String canonicalYamlPath, ResourceProvider resourceProvider) {
     var newToolDefinitions = <String, ToolDefinition>{};
+    var pathContext = resourceProvider.pathContext;
     for (var entry in yamlMap.entries) {
       var name = entry.key.toString();
       var toolMap = entry.value;
@@ -362,14 +379,10 @@ class ToolConfiguration {
             'At least one of "command" or "${Platform.operatingSystem}" must '
             'be defined for the tool $name.');
       }
-      bool validateExecutable(String executable) {
-        bool isExecutable(int mode) {
-          return (0x1 & ((mode >> 6) | (mode >> 3) | mode)) != 0;
-        }
 
-        var executableFile = File(executable);
-        var exeStat = executableFile.statSync();
-        if (exeStat.type == FileSystemEntityType.notFound) {
+      bool validateExecutable(String executable) {
+        var executableFile = resourceProvider.getFile(executable);
+        if (resourceProvider.isNotFound(executableFile)) {
           throw DartdocOptionError('Command executables must exist. '
               'The file "$executable" does not exist for tool $name.');
         }
@@ -377,7 +390,7 @@ class ToolConfiguration {
         var isDartCommand = ToolDefinition.isDartExecutable(executable);
         // Dart scripts don't need to be executable, because they'll be
         // executed with the Dart binary.
-        if (!isDartCommand && !isExecutable(exeStat.mode)) {
+        if (!isDartCommand && !resourceProvider.isExecutable(executableFile)) {
           throw DartdocOptionError('Non-Dart commands must be '
               'executable. The file "$executable" for tool $name does not have '
               'execute permission.');
@@ -385,11 +398,14 @@ class ToolConfiguration {
         return isDartCommand;
       }
 
-      var executable = pathContext.canonicalize(command.removeAt(0));
+      var executableRelatvePath = command.removeAt(0);
+      var executable = pathContext.canonicalize(
+          pathContext.join(canonicalYamlPath, executableRelatvePath));
       validateExecutable(executable);
       if (setupCommand != null) {
-        var setupExecutable =
-            pathContext.canonicalize(setupCommand.removeAt(0));
+        var setupExecutableRelativePath = setupCommand.removeAt(0);
+        var setupExecutable = pathContext.canonicalize(
+            pathContext.join(canonicalYamlPath, setupExecutableRelativePath));
         var isDartSetupCommand = validateExecutable(executable);
         // Setup commands aren't snapshotted, since they're only run once.
         setupCommand = (isDartSetupCommand
@@ -398,9 +414,9 @@ class ToolConfiguration {
             setupCommand;
       }
       newToolDefinitions[name] = ToolDefinition.fromCommand(
-          [executable] + command, setupCommand, description);
+          [executable] + command, setupCommand, description, resourceProvider);
     }
-    return ToolConfiguration._(newToolDefinitions);
+    return ToolConfiguration._(newToolDefinitions, resourceProvider);
   }
 }
 
@@ -496,8 +512,10 @@ abstract class DartdocOption<T> {
   /// and requires that one of [isDir] or [isFile] is set.
   final bool mustExist;
 
+  final ResourceProvider resourceProvider;
+
   DartdocOption(this.name, this.defaultsTo, this.help, this.isDir, this.isFile,
-      this.mustExist, this._convertYamlToType) {
+      this.mustExist, this._convertYamlToType, this.resourceProvider) {
     assert(!(isDir && isFile));
     if (isDir || isFile) assert(_isString || _isListString || _isMapString);
     if (mustExist) {
@@ -506,7 +524,7 @@ abstract class DartdocOption<T> {
   }
 
   /// Closure to convert yaml data into some other structure.
-  T Function(YamlMap, p.Context) _convertYamlToType;
+  ConvertYamlToType<T> _convertYamlToType;
 
   // The choice not to use reflection means there's some ugly type checking,
   // somewhat more ugly than we'd have to do anyway to automatically convert
@@ -573,8 +591,10 @@ abstract class DartdocOption<T> {
           '${valueWithContext.value.runtimeType}');
     }
     for (var path in resolvedPaths) {
-      var f = isDir ? Directory(path) : File(path);
-      if (!f.existsSync()) {
+      var f = isDir
+          ? resourceProvider.getFolder(path)
+          : resourceProvider.getFile(path);
+      if (!f.exists) {
         _onMissing(valueWithContext, path);
       }
     }
@@ -638,14 +658,20 @@ abstract class DartdocOption<T> {
   /// type.  If [mustExist] is true, will throw [DartdocFileMissing] for command
   /// line parameters and file paths in config files that don't point to
   /// corresponding files or directories.
-  T valueAt(Directory dir);
+  T valueAt(Folder dir);
 
   /// Calls [valueAt] with the working directory at the start of the program.
-  T valueAtCurrent() => valueAt(directoryCurrent);
+  T valueAtCurrent() => valueAt(_directoryCurrent);
+
+  Folder get _directoryCurrent =>
+      resourceProvider.getFolder(resourceProvider.pathContext.current);
+
+  String get _directoryCurrentPath => resourceProvider.pathContext.current;
 
   /// Calls [valueAt] on the directory this element is defined in.
-  T valueAtElement(Element element) =>
-      valueAt(Directory(p.canonicalize(p.basename(element.source.fullName))));
+  T valueAtElement(Element element) => valueAt(resourceProvider.getFolder(
+      resourceProvider.pathContext.canonicalize(
+          resourceProvider.pathContext.basename(element.source.fullName))));
 
   /// Adds a DartdocOption to the children of this DartdocOption.
   void add(DartdocOption<Object> option) {
@@ -683,21 +709,23 @@ class DartdocOptionFileSynth<T> extends DartdocOption<T>
     with DartdocSyntheticOption<T>, _DartdocFileOption<T> {
   bool _parentDirOverridesChild;
   @override
-  final T Function(DartdocSyntheticOption<T>, Directory) _compute;
+  final T Function(DartdocSyntheticOption<T>, Folder) _compute;
 
-  DartdocOptionFileSynth(String name, this._compute,
+  DartdocOptionFileSynth(
+      String name, this._compute, ResourceProvider resourceprovider,
       {bool mustExist = false,
       String help = '',
       bool isDir = false,
       bool isFile = false,
       bool parentDirOverridesChild,
-      T Function(YamlMap, p.Context) convertYamlToType})
-      : super(name, null, help, isDir, isFile, mustExist, convertYamlToType) {
+      ConvertYamlToType<T> convertYamlToType})
+      : super(name, null, help, isDir, isFile, mustExist, convertYamlToType,
+            resourceprovider) {
     _parentDirOverridesChild = parentDirOverridesChild;
   }
 
   @override
-  T valueAt(Directory dir) {
+  T valueAt(Folder dir) {
     var result = _valueAtFromFile(dir);
     if (result?.definingFile != null) {
       return _handlePathsInContext(result);
@@ -729,9 +757,10 @@ class DartdocOptionArgSynth<T> extends DartdocOption<T>
   bool _splitCommas;
 
   @override
-  final T Function(DartdocSyntheticOption<T>, Directory) _compute;
+  final T Function(DartdocSyntheticOption<T>, Folder) _compute;
 
-  DartdocOptionArgSynth(String name, this._compute,
+  DartdocOptionArgSynth(
+      String name, this._compute, ResourceProvider resourceProvider,
       {String abbr,
       bool mustExist = false,
       String help = '',
@@ -740,7 +769,8 @@ class DartdocOptionArgSynth<T> extends DartdocOption<T>
       bool isFile = false,
       bool negatable = false,
       bool splitCommas})
-      : super(name, null, help, isDir, isFile, mustExist, null) {
+      : super(name, null, help, isDir, isFile, mustExist, null,
+            resourceProvider) {
     _hide = hide;
     _negatable = negatable;
     _splitCommas = splitCommas;
@@ -754,7 +784,7 @@ class DartdocOptionArgSynth<T> extends DartdocOption<T>
   }
 
   @override
-  T valueAt(Directory dir) {
+  T valueAt(Folder dir) {
     if (_argResults.wasParsed(argName)) {
       return _valueAtFromArgs();
     }
@@ -782,23 +812,25 @@ class DartdocOptionArgSynth<T> extends DartdocOption<T>
 class DartdocOptionSyntheticOnly<T> extends DartdocOption<T>
     with DartdocSyntheticOption<T> {
   @override
-  final T Function(DartdocSyntheticOption<T>, Directory) _compute;
+  final T Function(DartdocSyntheticOption<T>, Folder) _compute;
 
-  DartdocOptionSyntheticOnly(String name, this._compute,
+  DartdocOptionSyntheticOnly(
+      String name, this._compute, ResourceProvider resourceProvider,
       {bool mustExist = false,
       String help = '',
       bool isDir = false,
       bool isFile = false})
-      : super(name, null, help, isDir, isFile, mustExist, null);
+      : super(
+            name, null, help, isDir, isFile, mustExist, null, resourceProvider);
 }
 
 abstract class DartdocSyntheticOption<T> implements DartdocOption<T> {
-  T Function(DartdocSyntheticOption<T>, Directory) get _compute;
+  T Function(DartdocSyntheticOption<T>, Folder) get _compute;
 
   @override
-  T valueAt(Directory dir) => _valueAtFromSynthetic(dir);
+  T valueAt(Folder dir) => _valueAtFromSynthetic(dir);
 
-  T _valueAtFromSynthetic(Directory dir) {
+  T _valueAtFromSynthetic(Folder dir) {
     var context = _OptionValueWithContext<T>(_compute(this, dir), dir.path);
     return _handlePathsInContext(context);
   }
@@ -817,13 +849,14 @@ abstract class DartdocSyntheticOption<T> implements DartdocOption<T> {
   }
 }
 
-typedef OptionGenerator = Future<List<DartdocOption<Object>>> Function();
+typedef OptionGenerator = Future<List<DartdocOption<Object>>> Function(
+    PackageMetaProvider);
 
 /// A [DartdocOption] that only contains other [DartdocOption]s and is not an
 /// option itself.
 class DartdocOptionSet extends DartdocOption<Null> {
-  DartdocOptionSet(String name)
-      : super(name, null, null, false, false, false, null);
+  DartdocOptionSet(String name, ResourceProvider resourceProvider)
+      : super(name, null, null, false, false, false, null, resourceProvider);
 
   /// Asynchronous factory that is the main entry point to initialize Dartdoc
   /// options for use.
@@ -832,17 +865,20 @@ class DartdocOptionSet extends DartdocOption<Null> {
   /// [optionGenerators] is a sequence of asynchronous functions that return
   /// [DartdocOption]s that will be added to the new option set.
   static Future<DartdocOptionSet> fromOptionGenerators(
-      String name, Iterable<OptionGenerator> optionGenerators) async {
-    var optionSet = DartdocOptionSet(name);
+      String name,
+      Iterable<OptionGenerator> optionGenerators,
+      PackageMetaProvider packageMetaProvider) async {
+    var optionSet =
+        DartdocOptionSet(name, packageMetaProvider.resourceProvider);
     for (var generator in optionGenerators) {
-      optionSet.addAll(await generator());
+      optionSet.addAll(await generator(packageMetaProvider));
     }
     return optionSet;
   }
 
   /// [DartdocOptionSet] always has the null value.
   @override
-  Null valueAt(Directory dir) => null;
+  Null valueAt(Folder dir) => null;
 
   /// Since we have no value, [_onMissing] does nothing.
   @override
@@ -866,7 +902,8 @@ class DartdocOptionArgOnly<T> extends DartdocOption<T>
   bool _negatable;
   bool _splitCommas;
 
-  DartdocOptionArgOnly(String name, T defaultsTo,
+  DartdocOptionArgOnly(
+      String name, T defaultsTo, ResourceProvider resourceProvider,
       {String abbr,
       bool mustExist = false,
       String help = '',
@@ -875,7 +912,8 @@ class DartdocOptionArgOnly<T> extends DartdocOption<T>
       bool isFile = false,
       bool negatable = false,
       bool splitCommas})
-      : super(name, defaultsTo, help, isDir, isFile, mustExist, null) {
+      : super(name, defaultsTo, help, isDir, isFile, mustExist, null,
+            resourceProvider) {
     _hide = hide;
     _negatable = negatable;
     _splitCommas = splitCommas;
@@ -905,7 +943,8 @@ class DartdocOptionArgFile<T> extends DartdocOption<T>
   bool _parentDirOverridesChild;
   bool _splitCommas;
 
-  DartdocOptionArgFile(String name, T defaultsTo,
+  DartdocOptionArgFile(
+      String name, T defaultsTo, ResourceProvider resourceProvider,
       {String abbr,
       bool mustExist = false,
       String help = '',
@@ -915,7 +954,8 @@ class DartdocOptionArgFile<T> extends DartdocOption<T>
       bool negatable = false,
       bool parentDirOverridesChild = false,
       bool splitCommas})
-      : super(name, defaultsTo, help, isDir, isFile, mustExist, null) {
+      : super(name, defaultsTo, help, isDir, isFile, mustExist, null,
+            resourceProvider) {
     _abbr = abbr;
     _hide = hide;
     _negatable = negatable;
@@ -936,7 +976,7 @@ class DartdocOptionArgFile<T> extends DartdocOption<T>
   /// Try to find an explicit argument setting this value, but if not, fall back
   /// to files finally, the default.
   @override
-  T valueAt(Directory dir) {
+  T valueAt(Folder dir) {
     var value = _valueAtFromArgs();
     value ??= _valueAtFromFiles(dir);
     value ??= defaultsTo;
@@ -963,15 +1003,16 @@ class DartdocOptionFileOnly<T> extends DartdocOption<T>
     with _DartdocFileOption<T> {
   bool _parentDirOverridesChild;
 
-  DartdocOptionFileOnly(String name, T defaultsTo,
+  DartdocOptionFileOnly(
+      String name, T defaultsTo, ResourceProvider resourceProvider,
       {bool mustExist = false,
       String help = '',
       bool isDir = false,
       bool isFile = false,
       bool parentDirOverridesChild = false,
-      T Function(YamlMap, p.Context) convertYamlToType})
+      ConvertYamlToType<T> convertYamlToType})
       : super(name, defaultsTo, help, isDir, isFile, mustExist,
-            convertYamlToType) {
+            convertYamlToType, resourceProvider) {
     _parentDirOverridesChild = parentDirOverridesChild;
   }
 
@@ -1003,7 +1044,7 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
 
   void _onMissingFromFiles(
       _OptionValueWithContext<Object> valueWithContext, String missingPath) {
-    var dartdocYaml = p.join(
+    var dartdocYaml = resourceProvider.pathContext.join(
         valueWithContext.canonicalDirectoryPath, valueWithContext.definingFile);
     throw DartdocFileMissing('Field ${fieldName} from ${dartdocYaml}, set to '
         '${valueWithContext.value}, resolves to missing path: '
@@ -1014,7 +1055,7 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
 
   /// Searches for a value in configuration files relative to [dir], and if not
   /// found, returns [defaultsTo].
-  T valueAt(Directory dir) {
+  T valueAt(Folder dir) {
     return _valueAtFromFiles(dir) ?? defaultsTo;
   }
 
@@ -1022,8 +1063,8 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
 
   // The value of this option from files will not change unless files are
   // modified during execution (not allowed in Dartdoc).
-  T _valueAtFromFiles(Directory dir) {
-    var key = p.canonicalize(dir.path);
+  T _valueAtFromFiles(Folder dir) {
+    var key = resourceProvider.pathContext.canonicalize(dir.path);
     if (!__valueAtFromFiles.containsKey(key)) {
       _OptionValueWithContext<Object> valueWithContext;
       if (parentDirOverridesChild) {
@@ -1038,11 +1079,11 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
 
   /// Searches all dartdoc_options files through parent directories, starting at
   /// [dir], for the option and returns one once found.
-  _OptionValueWithContext<Object> _valueAtFromFilesFirstFound(Directory dir) {
+  _OptionValueWithContext<Object> _valueAtFromFilesFirstFound(Folder dir) {
     _OptionValueWithContext<Object> value;
     while (true) {
       value = _valueAtFromFile(dir);
-      if (value != null || p.equals(dir.parent.path, dir.path)) break;
+      if (value != null || dir.parent == null) break;
       dir = dir.parent;
     }
     return value;
@@ -1051,20 +1092,20 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
   /// Searches all dartdoc_options files for the option, and returns the value
   /// in the top-most parent directory `dartdoc_options.yaml` file it is
   /// mentioned in.
-  _OptionValueWithContext<Object> _valueAtFromFilesLastFound(Directory dir) {
+  _OptionValueWithContext<Object> _valueAtFromFilesLastFound(Folder dir) {
     _OptionValueWithContext<Object> value;
     while (true) {
       var tmpValue = _valueAtFromFile(dir);
       if (tmpValue != null) value = tmpValue;
-      if (p.equals(dir.parent.path, dir.path)) break;
       dir = dir.parent;
+      if (dir == null) break;
     }
     return value;
   }
 
   /// Returns null if not set in the YAML file in this directory (or its
   /// parents).
-  _OptionValueWithContext<Object> _valueAtFromFile(Directory dir) {
+  _OptionValueWithContext<Object> _valueAtFromFile(Folder dir) {
     var yamlFileData = _yamlAtDirectory(dir);
     var contextPath = yamlFileData.canonicalDirectoryPath;
     dynamic yamlData = yamlFileData.data;
@@ -1090,7 +1131,8 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
       // _OptionValueWithContext into the return data here, and would not have
       // that be separate.
       if (_isMapString && _convertYamlToType == null) {
-        _convertYamlToType = (YamlMap yamlMap, p.Context pathContext) {
+        _convertYamlToType = (YamlMap yamlMap, String canonicalYamlPath,
+            ResourceProvider resourceProvider) {
           var returnData = <String, String>{};
           for (var entry in yamlMap.entries) {
             returnData[entry.key.toString()] = entry.value.toString();
@@ -1103,9 +1145,10 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
             'Unable to convert yaml to type for option: $fieldName, method not '
             'defined');
       }
-      var canonicalDirectoryPath = p.canonicalize(contextPath);
+      var canonicalDirectoryPath =
+          resourceProvider.pathContext.canonicalize(contextPath);
       returnData = _convertYamlToType(
-          yamlData, p.Context(current: canonicalDirectoryPath));
+          yamlData, canonicalDirectoryPath, resourceProvider);
     } else if (_isDouble) {
       if (yamlData is num) {
         returnData = yamlData.toDouble();
@@ -1121,24 +1164,30 @@ abstract class _DartdocFileOption<T> implements DartdocOption<T> {
         definingFile: 'dartdoc_options.yaml');
   }
 
-  _YamlFileData _yamlAtDirectory(Directory dir) {
-    var canonicalPaths = <String>[p.canonicalize(dir.path)];
+  _YamlFileData _yamlAtDirectory(Folder dir) {
+    var canonicalPaths = <String>[
+      resourceProvider.pathContext.canonicalize(dir.path)
+    ];
     if (!_yamlAtCanonicalPathCache.containsKey(canonicalPaths.first)) {
-      var yamlData = _YamlFileData({}, directoryCurrentPath);
-      if (dir.existsSync()) {
+      var yamlData = _YamlFileData({}, _directoryCurrentPath);
+      if (dir.exists) {
         File dartdocOptionsFile;
 
         while (true) {
-          dartdocOptionsFile = File(p.join(dir.path, 'dartdoc_options.yaml'));
-          if (dartdocOptionsFile.existsSync() ||
-              p.equals(dir.parent.path, dir.path)) break;
+          dartdocOptionsFile = resourceProvider.getFile(resourceProvider
+              .pathContext
+              .join(dir.path, 'dartdoc_options.yaml'));
+          if (dartdocOptionsFile.exists || dir.parent == null) {
+            break;
+          }
           dir = dir.parent;
-          canonicalPaths.add(p.canonicalize(dir.path));
+          canonicalPaths
+              .add(resourceProvider.pathContext.canonicalize(dir.path));
         }
-        if (dartdocOptionsFile.existsSync()) {
+        if (dartdocOptionsFile.exists) {
           yamlData = _YamlFileData(
               loadYaml(dartdocOptionsFile.readAsStringSync()),
-              p.canonicalize(dir.path));
+              resourceProvider.pathContext.canonicalize(dir.path));
         }
       }
       canonicalPaths.forEach((p) => _yamlAtCanonicalPathCache[p] = yamlData);
@@ -1167,7 +1216,7 @@ abstract class _DartdocArgOption<T> implements DartdocOption<T> {
   /// valueAt for arguments ignores the [dir] parameter and only uses command
   /// line arguments and the current working directory to resolve the result.
   @override
-  T valueAt(Directory dir) => _valueAtFromArgs() ?? defaultsTo;
+  T valueAt(Folder dir) => _valueAtFromArgs() ?? defaultsTo;
 
   /// For passing in to [int.parse] and [double.parse] `onError'.
   void _throwErrorForTypes(String value) {
@@ -1203,7 +1252,7 @@ abstract class _DartdocArgOption<T> implements DartdocOption<T> {
   }
 
   /// Generates an _OptionValueWithContext using the value of the argument from
-  /// the [argParser] and the working directory from [directoryCurrent].
+  /// the [argParser] and the working directory from [_directoryCurrent].
   ///
   /// Throws [UnsupportedError] if [T] is not a supported type.
   _OptionValueWithContext<Object> _valueAtFromArgsWithContext() {
@@ -1234,7 +1283,7 @@ abstract class _DartdocArgOption<T> implements DartdocOption<T> {
     } else {
       throw UnsupportedError('Type ${T} is not supported');
     }
-    return _OptionValueWithContext(retval, directoryCurrentPath);
+    return _OptionValueWithContext(retval, _directoryCurrentPath);
   }
 
   /// The name of this option as a command line argument.
@@ -1301,7 +1350,7 @@ abstract class _DartdocArgOption<T> implements DartdocOption<T> {
 abstract class DartdocOptionContextBase {
   DartdocOptionSet get optionSet;
 
-  Directory get context;
+  Folder get context;
 }
 
 /// An [DartdocOptionSet] wrapped in nice accessors specific to Dartdoc, which
@@ -1318,42 +1367,51 @@ class DartdocOptionContext extends DartdocOptionContextBase
   @override
   final DartdocOptionSet optionSet;
   @override
-  Directory context;
+  Folder context;
 
   // TODO(jcollins-g): Allow passing in structured data to initialize a
   // [DartdocOptionContext]'s arguments instead of having to parse strings
   // via optionSet.
   /// If [entity] is null, assume this is the initialization case and use
   /// the inputDir flag to determine the context.
-  DartdocOptionContext(this.optionSet, FileSystemEntity entity) {
-    if (entity == null) {
-      String inputDir = optionSet['inputDir'].valueAt(directoryCurrent) ??
-          directoryCurrentPath;
-      context = Directory(inputDir);
+  DartdocOptionContext(
+      this.optionSet, Resource resource, ResourceProvider resourceProvider) {
+    if (resource == null) {
+      var current = resourceProvider.pathContext.current;
+      String inputDir =
+          optionSet['inputDir'].valueAt(resourceProvider.getFolder(current)) ??
+              current;
+      context = resourceProvider.getFolder(inputDir);
     } else {
-      context = Directory(
-          p.canonicalize(entity is File ? entity.parent.path : entity.path));
+      context = resourceProvider.getFolder(resourceProvider.pathContext
+          .canonicalize(
+              resource is File ? resource.parent.path : resource.path));
     }
   }
 
   /// Build a DartdocOptionContext from an analyzer element (using its source
   /// location).
-  factory DartdocOptionContext.fromElement(
-      DartdocOptionSet optionSet, Element element) {
-    return DartdocOptionContext(optionSet, File(element.source.fullName));
+  factory DartdocOptionContext.fromElement(DartdocOptionSet optionSet,
+      Element element, ResourceProvider resourceProvider) {
+    return DartdocOptionContext(optionSet,
+        resourceProvider.getFile(element.source.fullName), resourceProvider);
   }
 
   /// Build a DartdocOptionContext from an existing [DartdocOptionContext] and a
   /// new analyzer [Element].
   factory DartdocOptionContext.fromContextElement(
-      DartdocOptionContext optionContext, Element element) {
-    return DartdocOptionContext.fromElement(optionContext.optionSet, element);
+      DartdocOptionContext optionContext,
+      Element element,
+      ResourceProvider resourceProvider) {
+    return DartdocOptionContext.fromElement(
+        optionContext.optionSet, element, resourceProvider);
   }
 
   /// Build a DartdocOptionContext from an existing [DartdocOptionContext].
-  factory DartdocOptionContext.fromContext(
-      DartdocOptionContext optionContext, FileSystemEntity entity) {
-    return DartdocOptionContext(optionContext.optionSet, entity);
+  factory DartdocOptionContext.fromContext(DartdocOptionContext optionContext,
+      Resource resource, ResourceProvider resourceProvider) {
+    return DartdocOptionContext(
+        optionContext.optionSet, resource, resourceProvider);
   }
 
   // All values defined in createDartdocOptions should be exposed here.
@@ -1420,6 +1478,8 @@ class DartdocOptionContext extends DartdocOptionContextBase
 
   bool get sdkDocs => optionSet['sdkDocs'].valueAt(context);
 
+  ResourceProvider get resourceProvider => optionSet.resourceProvider;
+
   String get sdkDir => optionSet['sdkDir'].valueAt(context);
 
   bool get showUndocumentedCategories =>
@@ -1451,28 +1511,31 @@ class DartdocOptionContext extends DartdocOptionContextBase
 Future<List<DartdocOption<Object>>> createDartdocOptions(
   PackageMetaProvider packageMetaProvider,
 ) async {
+  var resourceProvider = packageMetaProvider.resourceProvider;
   return [
-    DartdocOptionArgOnly<bool>('allowTools', false,
+    DartdocOptionArgOnly<bool>('allowTools', false, resourceProvider,
         help: 'Execute user-defined tools to fill in @tool directives.',
         negatable: true),
-    DartdocOptionArgFile<double>('ambiguousReexportScorerMinConfidence', 0.1,
+    DartdocOptionArgFile<double>(
+        'ambiguousReexportScorerMinConfidence', 0.1, resourceProvider,
         help: 'Minimum scorer confidence to suppress warning on ambiguous '
             'reexport.'),
-    DartdocOptionArgOnly<bool>('autoIncludeDependencies', false,
+    DartdocOptionArgOnly<bool>(
+        'autoIncludeDependencies', false, resourceProvider,
         help: 'Include all the used libraries into the docs, even the ones not '
             'in the current package or "include-external"',
         negatable: true),
-    DartdocOptionArgFile<List<String>>('categoryOrder', [],
+    DartdocOptionArgFile<List<String>>('categoryOrder', [], resourceProvider,
         help: 'A list of categories (not package names) to place first when '
             "grouping symbols on dartdoc's sidebar. Unmentioned categories are "
             'sorted after these.'),
     DartdocOptionFileOnly<CategoryConfiguration>(
-        'categories', CategoryConfiguration.empty,
+        'categories', CategoryConfiguration.empty, resourceProvider,
         convertYamlToType: CategoryConfiguration.fromYamlMap,
         help: 'A list of all categories, their display names, and markdown '
             'documentation in the order they are to be displayed.'),
     DartdocOptionSyntheticOnly<List<String>>('dropTextFrom',
-        (DartdocSyntheticOption<List<String>> option, Directory dir) {
+        (DartdocSyntheticOption<List<String>> option, Folder dir) {
       if (option.parent['hideSdkText'].valueAt(dir)) {
         return [
           'dart.async',
@@ -1494,59 +1557,65 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
         ];
       }
       return [];
-    }, help: 'Remove text from libraries with the following names.'),
-    DartdocOptionArgFile<String>('examplePathPrefix', null,
+    }, resourceProvider,
+        help: 'Remove text from libraries with the following names.'),
+    DartdocOptionArgFile<String>('examplePathPrefix', null, resourceProvider,
         isDir: true,
         help: 'Prefix for @example paths.\n(defaults to the project root)',
         mustExist: true),
-    DartdocOptionArgFile<List<String>>('exclude', [],
+    DartdocOptionArgFile<List<String>>('exclude', [], resourceProvider,
         help: 'Library names to ignore.', splitCommas: true),
-    DartdocOptionArgOnly<List<String>>('excludePackages', [],
+    DartdocOptionArgOnly<List<String>>('excludePackages', [], resourceProvider,
         help: 'Package names to ignore.', splitCommas: true),
     // This could be a ArgOnly, but trying to not provide too many ways
     // to set the flutter root.
     DartdocOptionSyntheticOnly<String>(
         'flutterRoot',
-        (DartdocSyntheticOption<String> option, Directory dir) =>
+        (DartdocSyntheticOption<String> option, Folder dir) =>
             resolveTildePath(Platform.environment['FLUTTER_ROOT']),
+        resourceProvider,
         isDir: true,
         help: 'Root of the Flutter SDK, specified from environment.',
         mustExist: true),
-    DartdocOptionArgOnly<bool>('hideSdkText', false,
+    DartdocOptionArgOnly<bool>('hideSdkText', false, resourceProvider,
         hide: true,
         help: 'Drop all text for SDK components.  Helpful for integration '
             'tests for dartdoc, probably not useful for anything else.',
         negatable: true),
-    DartdocOptionArgFile<List<String>>('include', [],
+    DartdocOptionArgFile<List<String>>('include', [], resourceProvider,
         help: 'Library names to generate docs for.', splitCommas: true),
-    DartdocOptionArgFile<List<String>>('includeExternal', null,
+    DartdocOptionArgFile<List<String>>(
+        'includeExternal', null, resourceProvider,
         isFile: true,
         help:
             'Additional (external) dart files to include; use "dir/fileName", '
             'as in lib/material.dart.',
         mustExist: true,
         splitCommas: true),
-    DartdocOptionArgOnly<bool>('includeSource', true,
+    DartdocOptionArgOnly<bool>('includeSource', true, resourceProvider,
         help: 'Show source code blocks.', negatable: true),
-    DartdocOptionArgOnly<bool>('injectHtml', false,
+    DartdocOptionArgOnly<bool>('injectHtml', false, resourceProvider,
         help: 'Allow the use of the {@inject-html} directive to inject raw '
             'HTML into dartdoc output.'),
-    DartdocOptionArgOnly<String>('input', directoryCurrentPath,
+    DartdocOptionArgOnly<String>(
+        'input', resourceProvider.pathContext.current, resourceProvider,
         isDir: true, help: 'Path to source directory', mustExist: true),
     DartdocOptionSyntheticOnly<String>('inputDir',
-        (DartdocSyntheticOption<String> option, Directory dir) {
+        (DartdocSyntheticOption<String> option, Folder dir) {
       if (option.parent['sdkDocs'].valueAt(dir)) {
         return option.parent['sdkDir'].valueAt(dir);
       }
       return option.parent['input'].valueAt(dir);
-    },
+    }, resourceProvider,
         help: 'Path to source directory (with override if --sdk-docs)',
         isDir: true,
         mustExist: true),
-    DartdocOptionSet('linkTo')
+    DartdocOptionSet('linkTo', resourceProvider)
       ..addAll([
-        DartdocOptionArgOnly<Map<String, String>>('hosted',
+        DartdocOptionArgOnly<Map<String, String>>(
+            'hosted',
             {'pub.dartlang.org': 'https://pub.dev/documentation/%n%/%v%'},
+            resourceProvider,
             help: 'Specify URLs for hosted pub packages'),
         DartdocOptionArgOnly<Map<String, String>>(
           'sdks',
@@ -1554,10 +1623,11 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
             'Dart': 'https://api.dart.dev/%b%/%v%',
             'Flutter': 'https://api.flutter.dev/flutter',
           },
+          resourceProvider,
           help: 'Specify URLs for SDKs.',
         ),
         DartdocOptionFileSynth<String>('url',
-            (DartdocSyntheticOption<String> option, Directory dir) {
+            (DartdocSyntheticOption<String> option, Folder dir) {
           PackageMeta packageMeta =
               option.parent.parent['packageMeta'].valueAt(dir);
           // Prefer SDK check first, then pub cache check.
@@ -1573,16 +1643,17 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
             if (hostMap.containsKey(hostedAt)) return hostMap[hostedAt];
           }
           return '';
-        }, help: 'Url to use for this particular package.'),
-        DartdocOptionArgOnly<bool>('remote', true,
+        }, resourceProvider, help: 'Url to use for this particular package.'),
+        DartdocOptionArgOnly<bool>('remote', true, resourceProvider,
             help: 'Allow links to be generated for packages outside this one.',
             negatable: true),
       ]),
-    DartdocOptionArgOnly<String>('output', p.join('doc', 'api'),
+    DartdocOptionArgOnly<String>('output',
+        resourceProvider.pathContext.join('doc', 'api'), resourceProvider,
         isDir: true, help: 'Path to output directory.'),
     DartdocOptionSyntheticOnly<PackageMeta>(
       'packageMeta',
-      (DartdocSyntheticOption<PackageMeta> option, Directory dir) {
+      (DartdocSyntheticOption<PackageMeta> option, Folder dir) {
         var packageMeta = packageMetaProvider.fromDir(dir);
         if (packageMeta == null) {
           throw DartdocOptionError(
@@ -1590,15 +1661,16 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
         }
         return packageMeta;
       },
+      resourceProvider,
     ),
-    DartdocOptionArgOnly<List<String>>('packageOrder', [],
+    DartdocOptionArgOnly<List<String>>('packageOrder', [], resourceProvider,
         help:
             'A list of package names to place first when grouping libraries in '
             'packages. Unmentioned packages are sorted after these.'),
-    DartdocOptionArgOnly<bool>('sdkDocs', false,
+    DartdocOptionArgOnly<bool>('sdkDocs', false, resourceProvider,
         help: 'Generate ONLY the docs for the Dart SDK.'),
     DartdocOptionArgSynth<String>('sdkDir',
-        (DartdocSyntheticOption<String> option, Directory dir) {
+        (DartdocSyntheticOption<String> option, Folder dir) {
       if (!option.parent['sdkDocs'].valueAt(dir) &&
           (option.root['topLevelPackageMeta'].valueAt(dir) as PackageMeta)
               .requiresFlutter) {
@@ -1608,16 +1680,19 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
           // [PackageBuilder.buildPackageGraph].
           return null;
         }
-        return p.join(flutterRoot, 'bin', 'cache', 'dart-sdk');
+        return resourceProvider.pathContext
+            .join(flutterRoot, 'bin', 'cache', 'dart-sdk');
       }
-      return defaultSdkDir.absolute.path;
-    }, help: 'Path to the SDK directory.', isDir: true, mustExist: true),
-    DartdocOptionArgFile<bool>('showUndocumentedCategories', false,
+      return resourceProvider.defaultSdkDir.path;
+    }, packageMetaProvider.resourceProvider,
+        help: 'Path to the SDK directory.', isDir: true, mustExist: true),
+    DartdocOptionArgFile<bool>(
+        'showUndocumentedCategories', false, resourceProvider,
         help: "Label categories that aren't documented", negatable: true),
     DartdocOptionSyntheticOnly<PackageMeta>('topLevelPackageMeta',
-        (DartdocSyntheticOption<PackageMeta> option, Directory dir) {
-      var packageMeta = packageMetaProvider
-          .fromDir(Directory(option.parent['inputDir'].valueAt(dir)));
+        (DartdocSyntheticOption<PackageMeta> option, Folder dir) {
+      var packageMeta = packageMetaProvider.fromDir(
+          resourceProvider.getFolder(option.parent['inputDir'].valueAt(dir)));
       if (packageMeta == null) {
         throw DartdocOptionError(
             'Unable to generate documentation: no package found');
@@ -1627,25 +1702,26 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
         throw DartdocOptionError('Package is invalid: $firstError');
       }
       return packageMeta;
-    }, help: 'PackageMeta object for the default package.'),
-    DartdocOptionArgOnly<bool>('useCategories', true,
+    }, resourceProvider, help: 'PackageMeta object for the default package.'),
+    DartdocOptionArgOnly<bool>('useCategories', true, resourceProvider,
         help: 'Display categories in the sidebar of packages'),
-    DartdocOptionArgOnly<bool>('validateLinks', true,
+    DartdocOptionArgOnly<bool>('validateLinks', true, resourceProvider,
         help: 'Runs the built-in link checker to display Dart context aware '
             'warnings for broken links (slow)',
         negatable: true),
-    DartdocOptionArgOnly<bool>('verboseWarnings', true,
+    DartdocOptionArgOnly<bool>('verboseWarnings', true, resourceProvider,
         help: 'Display extra debugging information and help with warnings.',
         negatable: true),
-    DartdocOptionFileOnly<bool>('excludeFooterVersion', false,
+    DartdocOptionFileOnly<bool>('excludeFooterVersion', false, resourceProvider,
         help: 'Excludes the package version number in the footer text'),
-    DartdocOptionFileOnly<ToolConfiguration>('tools', ToolConfiguration.empty,
+    DartdocOptionFileOnly<ToolConfiguration>(
+        'tools', ToolConfiguration.empty(resourceProvider), resourceProvider,
         convertYamlToType: ToolConfiguration.fromYamlMap,
         help: 'A map of tool names to executable paths. Each executable must '
             'exist. Executables for different platforms are specified by '
             'giving the platform name as a key, and a list of strings as the '
             'command.'),
-    DartdocOptionArgOnly<bool>('useBaseHref', false,
+    DartdocOptionArgOnly<bool>('useBaseHref', false, resourceProvider,
         help:
             'Use <base href> in generated files (legacy behavior). This option '
             'is temporary and support will be removed in the future. Use only '
@@ -1654,11 +1730,12 @@ Future<List<DartdocOption<Object>>> createDartdocOptions(
         negatable: false,
         hide: true),
     // TODO(jdkoren): Unhide when we have good support for another format.
-    DartdocOptionArgOnly<String>('format', 'html', hide: true),
+    DartdocOptionArgOnly<String>('format', 'html', resourceProvider,
+        hide: true),
     // TODO(jcollins-g): refactor so there is a single static "create" for
     // each DartdocOptionContext that traverses the inheritance tree itself.
-    ...await createExperimentOptions(),
+    ...await createExperimentOptions(resourceProvider),
     ...await createPackageWarningOptions(packageMetaProvider),
-    ...await createSourceLinkerOptions(),
+    ...await createSourceLinkerOptions(resourceProvider),
   ];
 }
diff --git a/lib/src/experiment_options.dart b/lib/src/experiment_options.dart
index 8c5b4d4e9a..9a136b0ee5 100644
--- a/lib/src/experiment_options.dart
+++ b/lib/src/experiment_options.dart
@@ -8,6 +8,7 @@
 ///
 library dartdoc.experiment_options;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 
@@ -19,10 +20,12 @@ abstract class DartdocExperimentOptionContext
 
 // TODO(jcollins-g): Implement YAML parsing for these flags and generation
 // of [DartdocExperimentOptionContext], once a YAML file is available.
-Future<List<DartdocOption<Object>>> createExperimentOptions() async {
+Future<List<DartdocOption<Object>>> createExperimentOptions(
+    ResourceProvider resourceProvider) async {
   return [
     // TODO(jcollins-g): Consider loading experiment values from dartdoc_options.yaml?
-    DartdocOptionArgOnly<List<String>>('enable-experiment', [],
+    DartdocOptionArgOnly<List<String>>(
+        'enable-experiment', [], resourceProvider,
         help: 'Enable or disable listed experiments.\n' +
             ExperimentStatus.knownFeatures.values
                 .where((e) => e.documentation != null)
diff --git a/lib/src/generator/generator.dart b/lib/src/generator/generator.dart
index ce09ff2572..b77dff3cc0 100644
--- a/lib/src/generator/generator.dart
+++ b/lib/src/generator/generator.dart
@@ -6,10 +6,11 @@
 library dartdoc.generator;
 
 import 'dart:async' show Future;
-import 'dart:io' show Directory;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/model/model.dart' show PackageGraph;
+import 'package:dartdoc/src/package_meta.dart';
 import 'package:dartdoc/src/warnings.dart';
 
 abstract class FileWriter {
@@ -55,9 +56,11 @@ mixin GeneratorContext on DartdocOptionContextBase {
   bool get useBaseHref => optionSet['useBaseHref'].valueAt(context);
 }
 
-Future<List<DartdocOption<Object>>> createGeneratorOptions() async {
+Future<List<DartdocOption<Object>>> createGeneratorOptions(
+    PackageMetaProvider packageMetaProvider) async {
+  var resourceProvider = packageMetaProvider.resourceProvider;
   return [
-    DartdocOptionArgFile<List<String>>('footer', [],
+    DartdocOptionArgFile<List<String>>('footer', [], resourceProvider,
         isFile: true,
         help:
             'Paths to files with content to add to page footers, but possibly '
@@ -66,7 +69,7 @@ Future<List<DartdocOption<Object>>> createGeneratorOptions() async {
             'to dedicated footer elements, use --footer-text instead.',
         mustExist: true,
         splitCommas: true),
-    DartdocOptionArgFile<List<String>>('footerText', [],
+    DartdocOptionArgFile<List<String>>('footerText', [], resourceProvider,
         isFile: true,
         help: 'Paths to files with content to add to page footers (next to the '
             'package name and version).',
@@ -74,30 +77,31 @@ Future<List<DartdocOption<Object>>> createGeneratorOptions() async {
         splitCommas: true),
     DartdocOptionSyntheticOnly<bool>(
       'addSdkFooter',
-      (DartdocSyntheticOption<bool> option, Directory dir) {
+      (DartdocSyntheticOption<bool> option, Folder dir) {
         return option.root['topLevelPackageMeta'].valueAt(dir).isSdk;
       },
+      resourceProvider,
       help: 'Whether the SDK footer text should be added (synthetic)',
     ),
-    DartdocOptionArgFile<List<String>>('header', [],
+    DartdocOptionArgFile<List<String>>('header', [], resourceProvider,
         isFile: true,
         help: 'Paths to files with content to add to page headers.',
         splitCommas: true),
-    DartdocOptionArgOnly<bool>('prettyIndexJson', false,
+    DartdocOptionArgOnly<bool>('prettyIndexJson', false, resourceProvider,
         help:
             'Generates `index.json` with indentation and newlines. The file is '
             'larger, but it\'s also easier to diff.',
         negatable: false),
-    DartdocOptionArgFile<String>('favicon', null,
+    DartdocOptionArgFile<String>('favicon', null, resourceProvider,
         isFile: true,
         help: 'A path to a favicon for the generated docs.',
         mustExist: true),
-    DartdocOptionArgOnly<String>('relCanonicalPrefix', null,
+    DartdocOptionArgOnly<String>('relCanonicalPrefix', null, resourceProvider,
         help:
             'If provided, add a rel="canonical" prefixed with provided value. '
             'Consider using if building many versions of the docs for public '
             'SEO; learn more at https://goo.gl/gktN6F.'),
-    DartdocOptionArgOnly<String>('templatesDir', null,
+    DartdocOptionArgOnly<String>('templatesDir', null, resourceProvider,
         isDir: true,
         mustExist: true,
         hide: true,
diff --git a/lib/src/generator/html_generator.dart b/lib/src/generator/html_generator.dart
index 5319db9dde..3a38b1495d 100644
--- a/lib/src/generator/html_generator.dart
+++ b/lib/src/generator/html_generator.dart
@@ -5,7 +5,6 @@
 library dartdoc.html_generator;
 
 import 'dart:async' show Future;
-import 'dart:io' show File;
 
 import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/generator/dartdoc_generator_backend.dart';
@@ -44,7 +43,8 @@ class HtmlGeneratorBackend extends DartdocGeneratorBackend {
     await _copyResources(writer);
     if (options.favicon != null) {
       // Allow overwrite of favicon.
-      var bytes = File(options.favicon).readAsBytesSync();
+      var bytes =
+          graph.resourceProvider.getFile(options.favicon).readAsBytesSync();
       writer.write(path.join('static-assets', 'favicon.png'), bytes,
           allowOverwrite: true);
     }
diff --git a/lib/src/io_utils.dart b/lib/src/io_utils.dart
index 33a8c6117e..c4a3cfaf18 100644
--- a/lib/src/io_utils.dart
+++ b/lib/src/io_utils.dart
@@ -6,10 +6,16 @@
 library dartdoc.io_utils;
 
 import 'dart:async';
-import 'dart:io';
+import 'dart:convert';
+import 'dart:io' as io;
 
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/physical_file_system.dart';
+import 'package:dartdoc/src/package_meta.dart';
 import 'package:path/path.dart' as path;
 
+Encoding utf8AllowMalformed = Utf8Codec(allowMalformed: true);
+
 /// Return a resolved path including the home directory in place of tilde
 /// references.
 String resolveTildePath(String originalPath) {
@@ -19,15 +25,75 @@ String resolveTildePath(String originalPath) {
 
   String homeDir;
 
-  if (Platform.isWindows) {
-    homeDir = path.absolute(Platform.environment['USERPROFILE']);
+  if (io.Platform.isWindows) {
+    homeDir = path.absolute(io.Platform.environment['USERPROFILE']);
   } else {
-    homeDir = path.absolute(Platform.environment['HOME']);
+    homeDir = path.absolute(io.Platform.environment['HOME']);
   }
 
   return path.join(homeDir, originalPath.substring(2));
 }
 
+extension ResourceProviderExtensions on ResourceProvider {
+  Folder createSystemTemp(String prefix) {
+    if (this is PhysicalResourceProvider) {
+      return getFolder(io.Directory.systemTemp.createTempSync(prefix).path);
+    } else {
+      return getFolder(pathContext.join('/tmp', prefix))..create();
+    }
+  }
+
+  Folder get defaultSdkDir {
+    if (this is PhysicalResourceProvider) {
+      var sdkDir = getFile(pathContext.absolute(io.Platform.resolvedExecutable))
+          .parent
+          .parent;
+      assert(pathContext.equals(
+          sdkDir.path, PubPackageMeta.sdkDirParent(sdkDir, this).path));
+      return sdkDir;
+    } else {
+      // TODO(srawlins): Return what is needed for tests.
+      return null;
+    }
+  }
+
+  String get resolvedExecutable {
+    if (this is PhysicalResourceProvider) {
+      return io.Platform.resolvedExecutable;
+    } else {
+      // TODO(srawlins): Return what is needed for tests.
+      return null;
+    }
+  }
+
+  bool isExecutable(File file) {
+    if (this is PhysicalResourceProvider) {
+      var mode = io.File(file.path).statSync().mode;
+      return (0x1 & ((mode >> 6) | (mode >> 3) | mode)) != 0;
+    } else {
+      // TODO(srawlins)
+      return false;
+    }
+  }
+
+  bool isNotFound(File file) {
+    if (this is PhysicalResourceProvider) {
+      return io.File(file.path).statSync().type ==
+          io.FileSystemEntityType.notFound;
+    } else {
+      return !file.exists;
+    }
+  }
+
+  String readAsMalformedAllowedStringSync(File file) {
+    if (this is PhysicalResourceProvider) {
+      return io.File(file.path).readAsStringSync(encoding: utf8AllowMalformed);
+    } else {
+      return file.readAsStringSync();
+    }
+  }
+}
+
 /// Lists the contents of [dir].
 ///
 /// If [recursive] is `true`, lists subdirectory contents (defaults to `false`).
@@ -37,8 +103,8 @@ String resolveTildePath(String originalPath) {
 /// The returned paths are guaranteed to begin with [dir].
 Iterable<String> listDir(String dir,
     {bool recursive = false,
-    Iterable<FileSystemEntity> Function(Directory dir) listDir}) {
-  listDir ??= (Directory dir) => dir.listSync();
+    Iterable<io.FileSystemEntity> Function(io.Directory dir) listDir}) {
+  listDir ??= (io.Directory dir) => dir.listSync();
 
   return _doList(dir, <String>{}, recursive, listDir);
 }
@@ -47,21 +113,21 @@ Iterable<String> _doList(
     String dir,
     Set<String> listedDirectories,
     bool recurse,
-    Iterable<FileSystemEntity> Function(Directory dir) listDir) sync* {
+    Iterable<io.FileSystemEntity> Function(io.Directory dir) listDir) sync* {
   // Avoid recursive symlinks.
-  var resolvedPath = Directory(dir).resolveSymbolicLinksSync();
+  var resolvedPath = io.Directory(dir).resolveSymbolicLinksSync();
   if (!listedDirectories.contains(resolvedPath)) {
     listedDirectories = Set<String>.from(listedDirectories);
     listedDirectories.add(resolvedPath);
 
-    for (var entity in listDir(Directory(dir))) {
+    for (var entity in listDir(io.Directory(dir))) {
       // Skip hidden files and directories
       if (path.basename(entity.path).startsWith('.')) {
         continue;
       }
 
       yield entity.path;
-      if (entity is Directory) {
+      if (entity is io.Directory) {
         if (recurse) {
           yield* _doList(entity.path, listedDirectories, recurse, listDir);
         }
diff --git a/lib/src/logging.dart b/lib/src/logging.dart
index fbaadd3b08..702c7c48f3 100644
--- a/lib/src/logging.dart
+++ b/lib/src/logging.dart
@@ -1,8 +1,10 @@
 import 'dart:async';
 import 'dart:convert';
-import 'dart:io';
+import 'dart:io' show stderr, stdout;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:cli_util/cli_logging.dart' show Ansi;
+import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ -130,21 +132,24 @@ abstract class LoggingContext implements DartdocOptionContextBase {
   bool get quiet => optionSet['quiet'].valueAt(context);
 }
 
-Future<List<DartdocOption<Object>>> createLoggingOptions() async {
+Future<List<DartdocOption<Object>>> createLoggingOptions(
+    PackageMetaProvider packageMetaProvider) async {
+  var resourceProvider = packageMetaProvider.resourceProvider;
   return [
-    DartdocOptionArgOnly<bool>('json', false,
+    DartdocOptionArgOnly<bool>('json', false, resourceProvider,
         help: 'Prints out progress JSON maps. One entry per line.',
         negatable: true),
-    DartdocOptionArgOnly<bool>('showProgress', Ansi.terminalSupportsAnsi,
+    DartdocOptionArgOnly<bool>(
+        'showProgress', Ansi.terminalSupportsAnsi, resourceProvider,
         help: 'Display progress indications to console stdout.',
         negatable: true),
     DartdocOptionArgSynth<bool>('quiet',
-        (DartdocSyntheticOption<Object> option, Directory dir) {
+        (DartdocSyntheticOption<Object> option, Folder dir) {
       if (option.root['generateDocs']?.valueAt(dir) == false) {
         return true;
       }
       return false;
-    },
+    }, resourceProvider,
         abbr: 'q',
         negatable: true,
         help: 'Only show warnings and errors; silence all other output.'),
diff --git a/lib/src/model/category.dart b/lib/src/model/category.dart
index fd7df304ad..9ae991b3c4 100644
--- a/lib/src/model/category.dart
+++ b/lib/src/model/category.dart
@@ -2,9 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:dartdoc/src/render/category_renderer.dart';
@@ -179,7 +178,8 @@ class Category extends Nameable
   File get documentationFile {
     if (_documentationFile == null) {
       if (categoryDefinition?.documentationMarkdown != null) {
-        _documentationFile = File(categoryDefinition.documentationMarkdown);
+        _documentationFile = _config.resourceProvider
+            .getFile(categoryDefinition.documentationMarkdown);
       }
     }
     return _documentationFile;
diff --git a/lib/src/model/comment_processable.dart b/lib/src/model/comment_processable.dart
index b78791e553..72c0395361 100644
--- a/lib/src/model/comment_processable.dart
+++ b/lib/src/model/comment_processable.dart
@@ -1,5 +1,3 @@
-import 'dart:io';
-
 import 'package:args/args.dart';
 import 'package:crypto/crypto.dart' as crypto;
 import 'package:dartdoc/src/model/model.dart';
@@ -74,6 +72,8 @@ mixin CommentProcessable on Documentable, Warnable, Locatable, SourceCodeMixin {
       // Remember, periods are legal in library names.
       fullyQualifiedName.replaceFirst('${library.fullyQualifiedName}.', '');
 
+  path.Context get pathContext => packageGraph.resourceProvider.pathContext;
+
   @visibleForTesting
   ModelElementRenderer get modelElementRenderer =>
       packageGraph.rendererFactory.modelElementRenderer;
@@ -198,8 +198,9 @@ mixin CommentProcessable on Documentable, Warnable, Locatable, SourceCodeMixin {
 
       var replacement = match[0]; // default to fully matched string.
 
-      var fragmentFile = File(path.join(dirPath, args['file']));
-      if (fragmentFile.existsSync()) {
+      var fragmentFile = packageGraph.resourceProvider.getFile(
+          pathContext.canonicalize(pathContext.join(dirPath, args['file'])));
+      if (fragmentFile.exists) {
         replacement = fragmentFile.readAsStringSync();
         if (lang.isNotEmpty) {
           replacement = replacement.replaceFirst('```', '```$lang');
@@ -234,7 +235,7 @@ mixin CommentProcessable on Documentable, Warnable, Locatable, SourceCodeMixin {
     // Extract PATH and fix the path separators.
     var src = results.rest.isEmpty
         ? ''
-        : results.rest.first.replaceAll('/', Platform.pathSeparator);
+        : results.rest.first.replaceAll('/', pathContext.separator);
     var args = <String, String>{
       'src': src,
       'lang': results['lang'],
diff --git a/lib/src/model/documentable.dart b/lib/src/model/documentable.dart
index 92810d8113..4c63497f41 100644
--- a/lib/src/model/documentable.dart
+++ b/lib/src/model/documentable.dart
@@ -2,10 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io' show File;
-
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
-import 'package:dartdoc/src/package_meta.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:path/path.dart' as p;
 
 import 'model.dart';
@@ -44,7 +43,10 @@ mixin MarkdownFileDocumentation implements Documentable, Canonicalization {
   DocumentLocation get documentedWhere;
 
   @override
-  String get documentation => documentationFile?.contents;
+  String get documentation => documentationFile == null
+      ? null
+      : packageGraph.resourceProvider
+          .readAsMalformedAllowedStringSync(documentationFile);
 
   Documentation __documentation;
 
@@ -59,7 +61,10 @@ mixin MarkdownFileDocumentation implements Documentable, Canonicalization {
 
   @override
   bool get hasDocumentation =>
-      documentationFile != null && documentationFile.contents.isNotEmpty;
+      documentationFile != null &&
+      packageGraph.resourceProvider
+          .readAsMalformedAllowedStringSync(documentationFile)
+          .isNotEmpty;
 
   @override
   bool get hasExtendedDocumentation =>
diff --git a/lib/src/model/model_element.dart b/lib/src/model/model_element.dart
index f571fa03c5..a01f3a5687 100644
--- a/lib/src/model/model_element.dart
+++ b/lib/src/model/model_element.dart
@@ -508,8 +508,8 @@ abstract class ModelElement extends Canonicalization
 
   @override
   DartdocOptionContext get config {
-    _config ??=
-        DartdocOptionContext.fromContextElement(packageGraph.config, element);
+    _config ??= DartdocOptionContext.fromContextElement(
+        packageGraph.config, element, packageGraph.resourceProvider);
     return _config;
   }
 
diff --git a/lib/src/model/package.dart b/lib/src/model/package.dart
index de31343afc..a8053e517a 100644
--- a/lib/src/model/package.dart
+++ b/lib/src/model/package.dart
@@ -2,10 +2,10 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:dartdoc/src/package_meta.dart';
 import 'package:dartdoc/src/warnings.dart';
@@ -111,12 +111,18 @@ class Package extends LibraryContainer
 
   @override
   String get documentation {
-    return hasDocumentationFile ? documentationFile.contents : null;
+    return hasDocumentationFile
+        ? packageGraph.resourceProvider
+            .readAsMalformedAllowedStringSync(documentationFile)
+        : null;
   }
 
   @override
   bool get hasDocumentation =>
-      documentationFile != null && documentationFile.contents.isNotEmpty;
+      documentationFile != null &&
+      packageGraph.resourceProvider
+          .readAsMalformedAllowedStringSync(documentationFile)
+          .isNotEmpty;
 
   @override
   bool get hasExtendedDocumentation => documentation.isNotEmpty;
@@ -332,7 +338,9 @@ class Package extends LibraryContainer
   @override
   DartdocOptionContext get config {
     _config ??= DartdocOptionContext.fromContext(
-        packageGraph.config, Directory(packagePath));
+        packageGraph.config,
+        packageGraph.resourceProvider.getFolder(packagePath),
+        packageGraph.resourceProvider);
     return _config;
   }
 
diff --git a/lib/src/model/package_builder.dart b/lib/src/model/package_builder.dart
index 8d90216a79..05337dd74f 100644
--- a/lib/src/model/package_builder.dart
+++ b/lib/src/model/package_builder.dart
@@ -21,14 +21,14 @@ import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
+import 'package:dartdoc/src/quiver.dart' as quiver;
 import 'package:analyzer/src/source/package_map_resolver.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/logging.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:dartdoc/src/package_meta.dart'
-    show PackageMeta, pubPackageMetaProvider;
-import 'package:dartdoc/src/quiver.dart' as quiver;
+    show PackageMeta, PackageMetaProvider;
 import 'package:dartdoc/src/render/renderer_factory.dart';
 import 'package:dartdoc/src/special_elements.dart';
 import 'package:package_config/discovery.dart' as package_config;
@@ -43,8 +43,9 @@ abstract class PackageBuilder {
 /// A package builder that understands pub package format.
 class PubPackageBuilder implements PackageBuilder {
   final DartdocOptionContext config;
+  final PackageMetaProvider packageMetaProvider;
 
-  PubPackageBuilder(this.config);
+  PubPackageBuilder(this.config, this.packageMetaProvider);
 
   @override
   Future<PackageGraph> buildPackageGraph() async {
@@ -67,7 +68,7 @@ class PubPackageBuilder implements PackageBuilder {
       sdk,
       hasEmbedderSdkFiles,
       rendererFactory,
-      pubPackageMetaProvider,
+      packageMetaProvider,
     );
     await getLibraries(newGraph);
     await newGraph.initializePackageGraph();
@@ -201,6 +202,7 @@ class PubPackageBuilder implements PackageBuilder {
   /// If [filePath] is not a library, returns null.
   Future<DartDocResolvedLibrary> processLibrary(String filePath) async {
     var name = filePath;
+    var directoryCurrentPath = config.resourceProvider.pathContext.current;
 
     if (name.startsWith(directoryCurrentPath)) {
       name = name.substring(directoryCurrentPath.length);
@@ -243,7 +245,7 @@ class PubPackageBuilder implements PackageBuilder {
   Set<PackageMeta> _packageMetasForFiles(Iterable<String> files) {
     var metas = <PackageMeta>{};
     for (var filename in files) {
-      metas.add(pubPackageMetaProvider.fromFilename(filename));
+      metas.add(packageMetaProvider.fromFilename(filename));
     }
     return metas;
   }
@@ -356,7 +358,8 @@ class PubPackageBuilder implements PackageBuilder {
   /// therein.
   Iterable<String> _includeExternalsFrom(Iterable<String> files) sync* {
     for (var file in files) {
-      var fileContext = DartdocOptionContext.fromContext(config, File(file));
+      var fileContext = DartdocOptionContext.fromContext(config,
+          config.resourceProvider.getFile(file), config.resourceProvider);
       if (fileContext.includeExternal != null) {
         yield* fileContext.includeExternal;
       }
diff --git a/lib/src/model/package_graph.dart b/lib/src/model/package_graph.dart
index 2870590b7c..4169837181 100644
--- a/lib/src/model/package_graph.dart
+++ b/lib/src/model/package_graph.dart
@@ -6,6 +6,7 @@ import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
@@ -237,6 +238,8 @@ class PackageGraph {
   /// Map of package name to Package.
   final Map<String, Package> packageMap = {};
 
+  ResourceProvider get resourceProvider => config.resourceProvider;
+
   final DartSdk sdk;
 
   Map<Source, SdkLibrary> _sdkLibrarySources;
diff --git a/lib/src/package_meta.dart b/lib/src/package_meta.dart
index 7df2de1d13..578014410b 100644
--- a/lib/src/package_meta.dart
+++ b/lib/src/package_meta.dart
@@ -5,9 +5,11 @@
 library dartdoc.package_meta;
 
 import 'dart:convert';
-import 'dart:io';
+import 'dart:io' show Platform, Process;
 
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:dartdoc/dartdoc.dart';
 import 'package:path/path.dart' as p;
 import 'package:yaml/yaml.dart';
@@ -15,13 +17,8 @@ import 'package:yaml/yaml.dart';
 import 'logging.dart';
 
 Map<String, PackageMeta> _packageMetaCache = {};
-Encoding utf8AllowMalformed = Utf8Codec(allowMalformed: true);
 
-Directory get defaultSdkDir {
-  var sdkDir = File(Platform.resolvedExecutable).parent.parent;
-  assert(p.equals(sdkDir.path, PubPackageMeta.sdkDirParent(sdkDir).path));
-  return sdkDir;
-}
+Encoding utf8AllowMalformed = Utf8Codec(allowMalformed: true);
 
 class PackageMetaFailure extends DartdocFailure {
   PackageMetaFailure(String message) : super(message);
@@ -39,6 +36,7 @@ final PackageMetaProvider pubPackageMetaProvider = PackageMetaProvider(
   PubPackageMeta.fromElement,
   PubPackageMeta.fromFilename,
   PubPackageMeta.fromDir,
+  PhysicalResourceProvider.INSTANCE,
 );
 
 /// Sets the supported way of constructing [PackageMeta] objects.
@@ -50,11 +48,20 @@ final PackageMetaProvider pubPackageMetaProvider = PackageMetaProvider(
 /// By using a different provider, these implementations can control how
 /// [PackageMeta] objects is built.
 class PackageMetaProvider {
-  final PackageMeta Function(LibraryElement, String) fromElement;
-  final PackageMeta Function(String) fromFilename;
-  final PackageMeta Function(Directory) fromDir;
+  final ResourceProvider resourceProvider;
+
+  final PackageMeta Function(LibraryElement, String, ResourceProvider)
+      _fromElement;
+  final PackageMeta Function(String, ResourceProvider) _fromFilename;
+  final PackageMeta Function(Folder, ResourceProvider) _fromDir;
+
+  PackageMeta fromElement(LibraryElement library, String s) =>
+      _fromElement(library, s, resourceProvider);
+  PackageMeta fromFilename(String s) => _fromFilename(s, resourceProvider);
+  PackageMeta fromDir(Folder dir) => _fromDir(dir, resourceProvider);
 
-  PackageMetaProvider(this.fromElement, this.fromFilename, this.fromDir);
+  PackageMetaProvider(this._fromElement, this._fromFilename, this._fromDir,
+      this.resourceProvider);
 }
 
 /// Describes a single package in the context of `dartdoc`.
@@ -66,19 +73,23 @@ class PackageMetaProvider {
 /// Overriding this is typically done by overriding factories as rest of
 /// `dartdoc` creates this object by calling these static factories.
 abstract class PackageMeta {
-  final Directory dir;
+  final Folder dir;
 
-  PackageMeta(this.dir);
+  final ResourceProvider resourceProvider;
+
+  PackageMeta(this.dir, this.resourceProvider);
 
   @override
   bool operator ==(Object other) {
     if (other is! PackageMeta) return false;
     PackageMeta otherMeta = other;
-    return p.equals(dir.absolute.path, otherMeta.dir.absolute.path);
+    return resourceProvider.pathContext.equals(dir.path, otherMeta.dir.path);
   }
 
   @override
-  int get hashCode => p.hash(dir.absolute.path);
+  int get hashCode => pathContext.hash(pathContext.absolute(dir.path));
+
+  p.Context get pathContext => resourceProvider.pathContext;
 
   /// Returns true if this represents a 'Dart' SDK.  A package can be part of
   /// Dart and Flutter at the same time, but if we are part of a Dart SDK
@@ -131,7 +142,8 @@ abstract class PackageMeta {
 
 /// Default implementation of [PackageMeta] depends on pub packages.
 abstract class PubPackageMeta extends PackageMeta {
-  PubPackageMeta(Directory dir) : super(dir);
+  PubPackageMeta(Folder dir, ResourceProvider resourceProvider)
+      : super(dir, resourceProvider);
 
   static List<List<String>> __sdkDirFilePaths;
 
@@ -156,48 +168,58 @@ abstract class PubPackageMeta extends PackageMeta {
 
   /// Returns the directory of the SDK if the given directory is inside a Dart
   /// SDK.  Returns null if the directory isn't a subdirectory of the SDK.
-  static final Map<String, Directory> _sdkDirParent = {};
+  static final _sdkDirParent = <String, Folder>{};
 
-  static Directory sdkDirParent(Directory dir) {
+  static Folder sdkDirParent(Folder dir, ResourceProvider resourceProvider) {
     var dirPathCanonical = p.canonicalize(dir.path);
     if (!_sdkDirParent.containsKey(dirPathCanonical)) {
       _sdkDirParent[dirPathCanonical] = null;
-      while (dir.existsSync()) {
+      while (dir.exists) {
         if (_sdkDirFilePaths.every((List<String> l) {
-          return l.any((f) => File(p.join(dir.path, f)).existsSync());
+          return l.any((f) => resourceProvider
+              .getFile(resourceProvider.pathContext.join(dir.path, f))
+              .exists);
         })) {
           _sdkDirParent[dirPathCanonical] = dir;
           break;
         }
-        if (p.equals(dir.path, dir.parent.path)) break;
         dir = dir.parent;
+        if (dir == null) break;
       }
     }
     return _sdkDirParent[dirPathCanonical];
   }
 
   /// Use this instead of fromDir where possible.
-  static PubPackageMeta fromElement(
-      LibraryElement libraryElement, String sdkDir) {
+  static PubPackageMeta fromElement(LibraryElement libraryElement,
+      String sdkDir, ResourceProvider resourceProvider) {
     if (libraryElement.isInSdk) {
-      return PubPackageMeta.fromDir(Directory(sdkDir));
+      return PubPackageMeta.fromDir(
+          resourceProvider.getFolder(sdkDir), resourceProvider);
     }
     return PubPackageMeta.fromDir(
-        File(p.canonicalize(libraryElement.source.fullName)).parent);
+        resourceProvider
+            .getFile(resourceProvider.pathContext
+                .canonicalize(libraryElement.source.fullName))
+            .parent,
+        resourceProvider);
   }
 
-  static PubPackageMeta fromFilename(String filename) {
-    return PubPackageMeta.fromDir(File(filename).parent);
+  static PubPackageMeta fromFilename(
+      String filename, ResourceProvider resourceProvider) {
+    return PubPackageMeta.fromDir(
+        resourceProvider.getFile(filename).parent, resourceProvider);
   }
 
   /// This factory is guaranteed to return the same object for any given
   /// [dir.absolute.path].  Multiple [dir.absolute.path]s will resolve to the
   /// same object if they are part of the same package.  Returns null
   /// if the directory is not part of a known package.
-  static PubPackageMeta fromDir(Directory dir) {
-    var original = dir.absolute;
+  static PubPackageMeta fromDir(Folder dir, ResourceProvider resourceProvider) {
+    var pathContext = resourceProvider.pathContext;
+    var original = resourceProvider.getFolder(pathContext.absolute(dir.path));
     dir = original;
-    if (!original.existsSync()) {
+    if (!original.exists) {
       throw PackageMetaFailure(
           'fatal error: unable to locate the input directory at ${original.path}.');
     }
@@ -205,37 +227,42 @@ abstract class PubPackageMeta extends PackageMeta {
     if (!_packageMetaCache.containsKey(dir.path)) {
       PackageMeta packageMeta;
       // There are pubspec.yaml files inside the SDK.  Ignore them.
-      var parentSdkDir = sdkDirParent(dir);
+      var parentSdkDir = sdkDirParent(dir, resourceProvider);
       if (parentSdkDir != null) {
-        packageMeta = _SdkMeta(parentSdkDir);
+        packageMeta = _SdkMeta(parentSdkDir, resourceProvider);
       } else {
-        while (dir.existsSync()) {
-          var pubspec = File(p.join(dir.path, 'pubspec.yaml'));
-          if (pubspec.existsSync()) {
-            packageMeta = _FilePackageMeta(dir);
+        while (dir.exists) {
+          var pubspec = resourceProvider
+              .getFile(pathContext.join(dir.path, 'pubspec.yaml'));
+          if (pubspec.exists) {
+            packageMeta = _FilePackageMeta(dir, resourceProvider);
             break;
           }
           // Allow a package to be at root (possible in a Windows setting with
           // drive letter mappings).
-          if (p.equals(dir.path, dir.parent.path)) break;
-          dir = dir.parent.absolute;
+          if (dir.parent == null) break;
+          // TODO(srawlins): or just... `.parent`?
+          dir =
+              resourceProvider.getFolder(pathContext.absolute(dir.parent.path));
         }
       }
-      _packageMetaCache[dir.absolute.path] = packageMeta;
+      _packageMetaCache[pathContext.absolute(dir.path)] = packageMeta;
     }
-    return _packageMetaCache[dir.absolute.path];
+    return _packageMetaCache[pathContext.absolute(dir.path)];
   }
 
   @override
   String sdkType(String flutterRootPath) {
     if (flutterRootPath != null) {
-      var flutterPackages = p.join(flutterRootPath, 'packages');
-      var flutterBinCache = p.join(flutterRootPath, 'bin', 'cache');
+      var flutterPackages = pathContext.join(flutterRootPath, 'packages');
+      var flutterBinCache = pathContext.join(flutterRootPath, 'bin', 'cache');
 
       /// Don't include examples or other non-SDK components as being the
       /// "Flutter SDK".
-      if (p.isWithin(flutterPackages, p.canonicalize(dir.absolute.path)) ||
-          p.isWithin(flutterBinCache, p.canonicalize(dir.absolute.path))) {
+      var canonicalizedDir = pathContext
+          .canonicalize(resourceProvider.pathContext.absolute(dir.path));
+      if (pathContext.isWithin(flutterPackages, canonicalizedDir) ||
+          pathContext.isWithin(flutterBinCache, canonicalizedDir)) {
         return 'Flutter';
       }
     }
@@ -246,24 +273,22 @@ abstract class PubPackageMeta extends PackageMeta {
 
   @override
   String get resolvedDir {
-    _resolvedDir ??= dir.resolveSymbolicLinksSync();
+    _resolvedDir ??= dir.resolveSymbolicLinksSync().path;
     return _resolvedDir;
   }
 }
 
-extension FileContents on File {
-  String get contents => readAsStringSync(encoding: utf8AllowMalformed);
-}
-
 class _FilePackageMeta extends PubPackageMeta {
   File _readme;
   File _license;
   File _changelog;
   Map<dynamic, dynamic> _pubspec;
 
-  _FilePackageMeta(Directory dir) : super(dir) {
-    var f = File(p.join(dir.path, 'pubspec.yaml'));
-    if (f.existsSync()) {
+  _FilePackageMeta(Folder dir, ResourceProvider resourceProvider)
+      : super(dir, resourceProvider) {
+    var f = resourceProvider
+        .getFile(resourceProvider.pathContext.join(dir.path, 'pubspec.yaml'));
+    if (f.exists) {
       _pubspec = loadYaml(f.readAsStringSync());
     } else {
       _pubspec = <dynamic, dynamic>{};
@@ -286,13 +311,15 @@ class _FilePackageMeta extends PubPackageMeta {
       // possibly by calculating hosting directly from pubspec.yaml or importing
       // a pub library to do this.
       // People could have a pub cache at root with Windows drive mappings.
-      if (p.split(p.canonicalize(dir.path)).length >= 3) {
+      if (pathContext.split(pathContext.canonicalize(dir.path)).length >= 3) {
         var pubCacheRoot = dir.parent.parent.parent.path;
-        var hosted = p.canonicalize(dir.parent.parent.path);
-        var hostname = p.canonicalize(dir.parent.path);
-        if (p.basename(hosted) == 'hosted' &&
-            Directory(p.join(pubCacheRoot, '_temp')).existsSync()) {
-          _hostedAt = p.basename(hostname);
+        var hosted = pathContext.canonicalize(dir.parent.parent.path);
+        var hostname = pathContext.canonicalize(dir.parent.path);
+        if (pathContext.basename(hosted) == 'hosted' &&
+            resourceProvider
+                .getFolder(pathContext.join(pubCacheRoot, '_temp'))
+                .exists) {
+          _hostedAt = pathContext.basename(hostname);
         }
       }
     }
@@ -303,9 +330,9 @@ class _FilePackageMeta extends PubPackageMeta {
   bool get isSdk => false;
 
   @override
-  bool get needsPubGet =>
-      !(File(p.join(dir.path, '.dart_tool', 'package_config.json'))
-          .existsSync());
+  bool get needsPubGet => !(resourceProvider
+      .getFile(pathContext.join(dir.path, '.dart_tool', 'package_config.json'))
+      .exists);
 
   @override
   void runPubGet(String flutterRoot) {
@@ -379,8 +406,8 @@ class _FilePackageMeta extends PubPackageMeta {
   }
 }
 
-File _locate(Directory dir, List<String> fileNames) {
-  var files = dir.listSync().whereType<File>().toList();
+File _locate(Folder dir, List<String> fileNames) {
+  var files = dir.getChildren().whereType<File>().toList();
 
   for (var name in fileNames) {
     for (var f in files) {
@@ -396,8 +423,10 @@ File _locate(Directory dir, List<String> fileNames) {
 class _SdkMeta extends PubPackageMeta {
   String sdkReadmePath;
 
-  _SdkMeta(Directory dir) : super(dir) {
-    sdkReadmePath = p.join(dir.path, 'lib', 'api_readme.md');
+  _SdkMeta(Folder dir, ResourceProvider resourceProvider)
+      : super(dir, resourceProvider) {
+    sdkReadmePath =
+        resourceProvider.pathContext.join(dir.path, 'lib', 'api_readme.md');
   }
 
   @override
@@ -416,8 +445,9 @@ class _SdkMeta extends PubPackageMeta {
 
   @override
   String get version {
-    var versionFile = File(p.join(dir.path, 'version'));
-    if (versionFile.existsSync()) return versionFile.readAsStringSync().trim();
+    var versionFile = resourceProvider
+        .getFile(resourceProvider.pathContext.join(dir.path, 'version'));
+    if (versionFile.exists) return versionFile.readAsStringSync().trim();
     return 'unknown';
   }
 
@@ -434,11 +464,13 @@ class _SdkMeta extends PubPackageMeta {
 
   @override
   File getReadmeContents() {
-    var f = File(p.join(dir.path, 'lib', 'api_readme.md'));
-    if (!f.existsSync()) {
-      f = File(p.join(dir.path, 'api_readme.md'));
+    var f = resourceProvider.getFile(
+        resourceProvider.pathContext.join(dir.path, 'lib', 'api_readme.md'));
+    if (!f.exists) {
+      f = resourceProvider.getFile(
+          resourceProvider.pathContext.join(dir.path, 'api_readme.md'));
     }
-    return f.existsSync() ? f : null;
+    return f.exists ? f : null;
   }
 
   @override
diff --git a/lib/src/source_linker.dart b/lib/src/source_linker.dart
index f4dafdbf9a..4bfd715042 100644
--- a/lib/src/source_linker.dart
+++ b/lib/src/source_linker.dart
@@ -5,6 +5,7 @@
 /// A library for getting external source code links for Dartdoc.
 library dartdoc.source_linker;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:meta/meta.dart';
@@ -29,22 +30,23 @@ abstract class SourceLinkerOptionContext implements DartdocOptionContextBase {
       optionSet['linkToSource']['uriTemplate'].valueAt(context);
 }
 
-Future<List<DartdocOption<Object>>> createSourceLinkerOptions() async {
+Future<List<DartdocOption<Object>>> createSourceLinkerOptions(
+    ResourceProvider resourceProvider) async {
   return [
-    DartdocOptionSet('linkToSource')
+    DartdocOptionSet('linkToSource', resourceProvider)
       ..addAll([
-        DartdocOptionArgFile<List<String>>('excludes', [],
+        DartdocOptionArgFile<List<String>>('excludes', [], resourceProvider,
             isDir: true,
             help:
                 'A list of directories to exclude from linking to a source code repository.'),
         // TODO(jcollins-g): Use [DartdocOptionArgSynth], possibly in combination with a repository type and the root directory, and get revision number automatically
-        DartdocOptionArgOnly<String>('revision', null,
+        DartdocOptionArgOnly<String>('revision', null, resourceProvider,
             help: 'Revision number to insert into the URI.'),
-        DartdocOptionArgFile<String>('root', null,
+        DartdocOptionArgFile<String>('root', null, resourceProvider,
             isDir: true,
             help:
                 'Path to a local directory that is the root of the repository we link to.  All source code files under this directory will be linked.'),
-        DartdocOptionArgFile<String>('uriTemplate', null,
+        DartdocOptionArgFile<String>('uriTemplate', null, resourceProvider,
             help:
                 '''Substitute into this template to generate a uri for an element's source code.
              Dartdoc dynamically substitutes the following fields into the template:
diff --git a/lib/src/tool_runner.dart b/lib/src/tool_runner.dart
index b8f7d5374f..c835ac7688 100644
--- a/lib/src/tool_runner.dart
+++ b/lib/src/tool_runner.dart
@@ -5,10 +5,11 @@
 library dartdoc.tool_runner;
 
 import 'dart:async';
-import 'dart:io';
+import 'dart:io' show Process, ProcessException;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/io_utils.dart';
-import 'package:path/path.dart' as path;
+import 'package:path/path.dart' as p;
 import 'dartdoc_options.dart';
 
 typedef ToolErrorCallback = void Function(String message);
@@ -23,31 +24,37 @@ final MultiFutureTracker<void> _toolTracker = MultiFutureTracker(4);
 ///
 /// This will remove any temporary files created by the tool runner.
 class ToolTempFileTracker {
-  final Directory temporaryDirectory;
+  final ResourceProvider resourceProvider;
+  final Folder temporaryDirectory;
 
-  ToolTempFileTracker._()
+  ToolTempFileTracker._(this.resourceProvider)
       : temporaryDirectory =
-            Directory.systemTemp.createTempSync('dartdoc_tools_');
+            resourceProvider.createSystemTemp('dartdoc_tools_');
 
   static ToolTempFileTracker _instance;
 
-  static ToolTempFileTracker get instance =>
-      _instance ??= ToolTempFileTracker._();
+  static ToolTempFileTracker get instance => _instance;
+
+  static ToolTempFileTracker createInstance(
+          ResourceProvider resourceProvider) =>
+      _instance ??= ToolTempFileTracker._(resourceProvider);
 
   int _temporaryFileCount = 0;
 
   Future<File> createTemporaryFile() async {
     _temporaryFileCount++;
-    var tempFile = File(path.join(
-        temporaryDirectory.absolute.path, 'input_$_temporaryFileCount'));
-    await tempFile.create(recursive: true);
+    // TODO(srawlins): Assume [temporaryDirectory]'s path is always absolute.
+    var tempFile = resourceProvider.getFile(resourceProvider.pathContext.join(
+        resourceProvider.pathContext.absolute(temporaryDirectory.path),
+        'input_$_temporaryFileCount'));
+    await tempFile.writeAsStringSync('');
     return tempFile;
   }
 
   /// Call once no more files are to be created.
   Future<void> dispose() async {
-    if (temporaryDirectory.existsSync()) {
-      return temporaryDirectory.delete(recursive: true);
+    if (temporaryDirectory.exists) {
+      return temporaryDirectory.delete();
     }
   }
 }
@@ -73,7 +80,7 @@ class ToolRunner {
     String commandPath;
 
     if (isDartSetup) {
-      commandPath = Platform.resolvedExecutable;
+      commandPath = toolConfiguration.resourceProvider.resolvedExecutable;
     } else {
       commandPath = args.removeAt(0);
     }
@@ -95,8 +102,8 @@ class ToolRunner {
           await Process.run(commandPath, args, environment: environment);
       if (result.exitCode != 0) {
         toolErrorCallback('Tool "$name" returned non-zero exit code '
-            '(${result.exitCode}) when run as '
-            '"${commandString()}" from ${Directory.current}\n'
+            '(${result.exitCode}) when run as "${commandString()}" from '
+            '${pathContext.current}\n'
             'Input to $name was:\n'
             '$content\n'
             'Stderr output was:\n${result.stderr}\n');
@@ -155,14 +162,16 @@ class ToolRunner {
     // file before running the tool synchronously.
 
     // Write the content to a temp file.
-    var tmpFile = await ToolTempFileTracker.instance.createTemporaryFile();
-    await tmpFile.writeAsString(content);
+    var tmpFile = await ToolTempFileTracker.createInstance(
+            toolConfiguration.resourceProvider)
+        .createTemporaryFile();
+    tmpFile.writeAsStringSync(content);
 
     // Substitute the temp filename for the "$INPUT" token, and all of the other
     // environment variables. Variables are allowed to either be in $(VAR) form,
     // or $VAR form.
     var envWithInput = {
-      'INPUT': tmpFile.absolute.path,
+      'INPUT': pathContext.absolute(tmpFile.path),
       'TOOL_COMMAND': toolDefinition.command[0],
       ...environment,
     };
@@ -173,8 +182,10 @@ class ToolRunner {
       // script writer can use this instead of Platform.script if they want to
       // find out where their script was coming from as an absolute path on the
       // filesystem.
-      envWithInput['DART_SNAPSHOT_CACHE'] =
-          SnapshotCache.instance.snapshotCache.absolute.path;
+      envWithInput['DART_SNAPSHOT_CACHE'] = pathContext.absolute(
+          SnapshotCache.createInstance(toolConfiguration.resourceProvider)
+              .snapshotCache
+              .path);
       if (toolDefinition.setupCommand != null) {
         envWithInput['DART_SETUP_COMMAND'] = toolDefinition.setupCommand[0];
       }
@@ -216,4 +227,6 @@ class ToolRunner {
           envWithInput, toolErrorCallback);
     }
   }
+
+  p.Context get pathContext => toolConfiguration.resourceProvider.pathContext;
 }
diff --git a/lib/src/warnings.dart b/lib/src/warnings.dart
index ade343e762..ef564d6464 100644
--- a/lib/src/warnings.dart
+++ b/lib/src/warnings.dart
@@ -2,9 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io';
-
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/logging.dart';
 import 'package:dartdoc/src/model/model.dart';
@@ -26,8 +25,9 @@ abstract class PackageWarningOptionContext implements DartdocOptionContextBase {
 Future<List<DartdocOption<Object>>> createPackageWarningOptions(
   PackageMetaProvider packageMetaProvider,
 ) async {
+  var resourceProvider = packageMetaProvider.resourceProvider;
   return [
-    DartdocOptionArgOnly<bool>('allowNonLocalWarnings', false,
+    DartdocOptionArgOnly<bool>('allowNonLocalWarnings', false, resourceProvider,
         negatable: true,
         help: 'Show warnings from packages we are not documenting locally.'),
 
@@ -35,43 +35,48 @@ Future<List<DartdocOption<Object>>> createPackageWarningOptions(
     // for individual packages are command-line only.  This will allow
     // meta-packages like Flutter to control whether warnings are displayed for
     // packages they don't control.
-    DartdocOptionArgOnly<List<String>>('allowWarningsInPackages', null,
+    DartdocOptionArgOnly<List<String>>(
+        'allowWarningsInPackages', null, resourceProvider,
         help:
             'Package names to display warnings for (ignore all others if set).'),
-    DartdocOptionArgOnly<List<String>>('allowErrorsInPackages', null,
+    DartdocOptionArgOnly<List<String>>(
+        'allowErrorsInPackages', null, resourceProvider,
         help: 'Package names to display errors for (ignore all others if set)'),
-    DartdocOptionArgOnly<List<String>>('ignoreWarningsInPackages', null,
-        help:
-            'Package names to ignore warnings for.  Takes priority over allow-warnings-in-packages'),
-    DartdocOptionArgOnly<List<String>>('ignoreErrorsInPackages', null,
-        help:
-            'Package names to ignore errors for. Takes priority over allow-errors-in-packages'),
+    DartdocOptionArgOnly<List<String>>(
+        'ignoreWarningsInPackages', null, resourceProvider,
+        help: 'Package names to ignore warnings for.  Takes priority over '
+            'allow-warnings-in-packages'),
+    DartdocOptionArgOnly<List<String>>(
+        'ignoreErrorsInPackages', null, resourceProvider,
+        help: 'Package names to ignore errors for. Takes priority over '
+            'allow-errors-in-packages'),
     // Options for globally enabling/disabling warnings and errors across
     // packages.  Loaded from dartdoc_options.yaml, but command line arguments
     // will override.
-    DartdocOptionArgFile<List<String>>('errors', null,
-        help:
-            'Additional warning names to force as errors.  Specify an empty list to force defaults (overriding dartdoc_options.yaml)\nDefaults:\n' +
-                (packageWarningDefinitions.values
-                        .where((d) =>
-                            d.defaultWarningMode == PackageWarningMode.error)
-                        .toList()
-                          ..sort())
-                    .map((d) => '   ${d.warningName}: ${d.shortHelp}')
-                    .join('\n')),
-    DartdocOptionArgFile<List<String>>('ignore', null,
-        help:
-            'Additional warning names to ignore.  Specify an empty list to force defaults (overriding dartdoc_options.yaml).\nDefaults:\n' +
-                (packageWarningDefinitions.values
-                        .where((d) =>
-                            d.defaultWarningMode == PackageWarningMode.ignore)
-                        .toList()
-                          ..sort())
-                    .map((d) => '   ${d.warningName}: ${d.shortHelp}')
-                    .join('\n')),
-    DartdocOptionArgFile<List<String>>('warnings', null,
+    DartdocOptionArgFile<List<String>>('errors', null, resourceProvider,
+        help: 'Additional warning names to force as errors.  Specify an empty '
+                'list to force defaults (overriding dartdoc_options.yaml)\nDefaults:\n' +
+            (packageWarningDefinitions.values
+                    .where(
+                        (d) => d.defaultWarningMode == PackageWarningMode.error)
+                    .toList()
+                      ..sort())
+                .map((d) => '   ${d.warningName}: ${d.shortHelp}')
+                .join('\n')),
+    DartdocOptionArgFile<List<String>>('ignore', null, resourceProvider,
+        help: 'Additional warning names to ignore.  Specify an empty list to '
+                'force defaults (overriding dartdoc_options.yaml).\nDefaults:\n' +
+            (packageWarningDefinitions.values
+                    .where((d) =>
+                        d.defaultWarningMode == PackageWarningMode.ignore)
+                    .toList()
+                      ..sort())
+                .map((d) => '   ${d.warningName}: ${d.shortHelp}')
+                .join('\n')),
+    DartdocOptionArgFile<List<String>>('warnings', null, resourceProvider,
         help:
-            'Additional warning names to show as warnings (instead of error or ignore, if not warning by default).\nDefaults:\n' +
+            'Additional warning names to show as warnings (instead of error or '
+                    'ignore, if not warning by default).\nDefaults:\n' +
                 (packageWarningDefinitions.values
                         .where((d) =>
                             d.defaultWarningMode == PackageWarningMode.warn)
@@ -82,8 +87,9 @@ Future<List<DartdocOption<Object>>> createPackageWarningOptions(
     // Synthetic option uses a factory to build a PackageWarningOptions from all the above flags.
     DartdocOptionSyntheticOnly<PackageWarningOptions>(
       'packageWarningOptions',
-      (DartdocSyntheticOption<PackageWarningOptions> option, Directory dir) =>
+      (DartdocSyntheticOption<PackageWarningOptions> option, Folder dir) =>
           PackageWarningOptions.fromOptions(option, dir, packageMetaProvider),
+      resourceProvider,
     ),
   ];
 }
@@ -317,10 +323,9 @@ class PackageWarningOptions {
     }
   }
 
-  /// [packageMeta] parameter is for testing.
   static PackageWarningOptions fromOptions(
     DartdocSyntheticOption<PackageWarningOptions> option,
-    Directory dir,
+    Folder dir,
     PackageMetaProvider packageMetaProvider,
   ) {
     // First, initialize defaults.
diff --git a/test/dartdoc_options_test.dart b/test/dartdoc_options_test.dart
index 3054ef6782..1d8a63959e 100644
--- a/test/dartdoc_options_test.dart
+++ b/test/dartdoc_options_test.dart
@@ -4,9 +4,10 @@
 
 library dartdoc.options_test;
 
-import 'dart:io';
-
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 import 'package:yaml/yaml.dart';
@@ -18,10 +19,10 @@ class ConvertedOption {
 
   ConvertedOption._(this.param1, this.param2, this.myContextPath);
 
-  static ConvertedOption fromYamlMap(YamlMap yamlMap, path.Context context) {
+  static ConvertedOption fromYamlMap(YamlMap yamlMap, String canonicalYamlPath,
+      ResourceProvider resourceProvider) {
     String p1;
     String p2;
-    var contextPath = context.current;
 
     for (var entry in yamlMap.entries) {
       switch (entry.key.toString()) {
@@ -33,20 +34,22 @@ class ConvertedOption {
           break;
       }
     }
-    return ConvertedOption._(p1, p2, contextPath);
+    return ConvertedOption._(p1, p2, canonicalYamlPath);
   }
 }
 
 void main() {
+  var resourceProvider = pubPackageMetaProvider.resourceProvider;
+
   DartdocOptionSet dartdocOptionSetFiles;
   DartdocOptionSet dartdocOptionSetArgs;
   DartdocOptionSet dartdocOptionSetAll;
   DartdocOptionSet dartdocOptionSetSynthetic;
-  Directory tempDir;
-  Directory firstDir;
-  Directory secondDir;
-  Directory secondDirFirstSub;
-  Directory secondDirSecondSub;
+  Folder tempDir;
+  Folder firstDir;
+  Folder secondDir;
+  Folder secondDirFirstSub;
+  Folder secondDirSecondSub;
 
   File dartdocOptionsOne;
   File dartdocOptionsTwo;
@@ -54,118 +57,145 @@ void main() {
   File firstExisting;
 
   setUpAll(() {
-    dartdocOptionSetSynthetic = DartdocOptionSet('dartdoc');
-    dartdocOptionSetSynthetic
-        .add(DartdocOptionArgFile<int>('mySpecialInteger', 91));
+    dartdocOptionSetSynthetic = DartdocOptionSet('dartdoc', resourceProvider);
+    dartdocOptionSetSynthetic.add(
+        DartdocOptionArgFile<int>('mySpecialInteger', 91, resourceProvider));
     dartdocOptionSetSynthetic.add(
         DartdocOptionSyntheticOnly<List<String>>('vegetableLoader',
-            (DartdocSyntheticOption<List<String>> option, Directory dir) {
+            (DartdocSyntheticOption<List<String>> option, Folder dir) {
       if (option.root['mySpecialInteger'].valueAt(dir) > 20) {
         return <String>['existing.dart'];
       } else {
         return <String>['not_existing.dart'];
       }
-    }));
+    }, resourceProvider));
     dartdocOptionSetSynthetic.add(
         DartdocOptionSyntheticOnly<List<String>>('vegetableLoaderChecked',
-            (DartdocSyntheticOption<List<String>> option, Directory dir) {
+            (DartdocSyntheticOption<List<String>> option, Folder dir) {
       return option.root['vegetableLoader'].valueAt(dir);
-    }, isFile: true, mustExist: true));
+    }, resourceProvider, isFile: true, mustExist: true));
     dartdocOptionSetSynthetic.add(DartdocOptionFileSynth<double>('double',
-        (DartdocSyntheticOption<double> option, Directory dir) {
+        (DartdocSyntheticOption<double> option, Folder dir) {
       return 3.7 + 4.1;
-    }));
+    }, resourceProvider));
     dartdocOptionSetSynthetic.add(
         DartdocOptionArgSynth<String>('nonCriticalFileOption',
-            (DartdocSyntheticOption<String> option, Directory dir) {
+            (DartdocSyntheticOption<String> option, Folder dir) {
       return option.root['vegetableLoader'].valueAt(dir).first;
-    }, isFile: true));
+    }, resourceProvider, isFile: true));
 
-    dartdocOptionSetFiles = DartdocOptionSet('dartdoc');
-    dartdocOptionSetFiles
-        .add(DartdocOptionFileOnly<List<String>>('categoryOrder', []));
-    dartdocOptionSetFiles.add(DartdocOptionFileOnly<double>('double', 3.0));
+    dartdocOptionSetFiles = DartdocOptionSet('dartdoc', resourceProvider);
+    dartdocOptionSetFiles.add(DartdocOptionFileOnly<List<String>>(
+        'categoryOrder', [], resourceProvider));
     dartdocOptionSetFiles
-        .add(DartdocOptionFileOnly<int>('mySpecialInteger', 42));
+        .add(DartdocOptionFileOnly<double>('double', 3.0, resourceProvider));
+    dartdocOptionSetFiles.add(
+        DartdocOptionFileOnly<int>('mySpecialInteger', 42, resourceProvider));
     dartdocOptionSetFiles.add(DartdocOptionFileOnly<Map<String, String>>(
-        'mapOption', {'hello': 'world'}));
+        'mapOption', {'hello': 'world'}, resourceProvider));
     dartdocOptionSetFiles.add(DartdocOptionFileOnly<List<String>>(
-        'fileOptionList', [],
+        'fileOptionList', [], resourceProvider,
         isFile: true, mustExist: true));
-    dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>('fileOption', null,
+    dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>(
+        'fileOption', null, resourceProvider,
         isFile: true, mustExist: true));
     dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>(
-        'parentOverride', 'oops',
+        'parentOverride', 'oops', resourceProvider,
         parentDirOverridesChild: true));
     dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>(
-        'nonCriticalFileOption', null,
+        'nonCriticalFileOption', null, resourceProvider,
         isFile: true));
-    dartdocOptionSetFiles.add(DartdocOptionSet('nestedOption')
-      ..addAll([DartdocOptionFileOnly<bool>('flag', false)]));
-    dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>('dirOption', null,
+    dartdocOptionSetFiles.add(DartdocOptionSet('nestedOption', resourceProvider)
+      ..addAll([DartdocOptionFileOnly<bool>('flag', false, resourceProvider)]));
+    dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>(
+        'dirOption', null, resourceProvider,
         isDir: true, mustExist: true));
     dartdocOptionSetFiles.add(DartdocOptionFileOnly<String>(
-        'nonCriticalDirOption', null,
+        'nonCriticalDirOption', null, resourceProvider,
         isDir: true));
     dartdocOptionSetFiles.add(DartdocOptionFileOnly<ConvertedOption>(
       'convertThisMap',
       null,
+      resourceProvider,
       convertYamlToType: ConvertedOption.fromYamlMap,
     ));
 
-    dartdocOptionSetArgs = DartdocOptionSet('dartdoc');
-    dartdocOptionSetArgs
-        .add(DartdocOptionArgOnly<bool>('cauliflowerSystem', false));
-    dartdocOptionSetArgs
-        .add(DartdocOptionArgOnly<String>('extraSpecial', 'something'));
-    dartdocOptionSetArgs.add(
-        DartdocOptionArgOnly<List<String>>('excludeFiles', ['one', 'two']));
-    dartdocOptionSetArgs
-        .add(DartdocOptionArgOnly<int>('number_of_heads', 3, abbr: 'h'));
-    dartdocOptionSetArgs
-        .add(DartdocOptionArgOnly<double>('respawnProbability', 0.2));
-    dartdocOptionSetArgs.add(DartdocOptionSet('warn')
-      ..addAll([DartdocOptionArgOnly<bool>('unrecognizedVegetable', false)]));
+    dartdocOptionSetArgs = DartdocOptionSet('dartdoc', resourceProvider);
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<bool>(
+        'cauliflowerSystem', false, resourceProvider));
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<String>(
+        'extraSpecial', 'something', resourceProvider));
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<List<String>>(
+        'excludeFiles', ['one', 'two'], resourceProvider));
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<int>(
+        'number_of_heads', 3, resourceProvider,
+        abbr: 'h'));
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<double>(
+        'respawnProbability', 0.2, resourceProvider));
+    dartdocOptionSetArgs.add(DartdocOptionSet('warn', resourceProvider)
+      ..addAll([
+        DartdocOptionArgOnly<bool>(
+            'unrecognizedVegetable', false, resourceProvider)
+      ]));
     dartdocOptionSetArgs.add(DartdocOptionArgOnly<Map<String, String>>(
-        'aFancyMapVariable', {'hello': 'map world'},
+        'aFancyMapVariable', {'hello': 'map world'}, resourceProvider,
         splitCommas: true));
-    dartdocOptionSetArgs.add(DartdocOptionArgOnly<List<String>>('filesFlag', [],
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<List<String>>(
+        'filesFlag', [], resourceProvider,
         isFile: true, mustExist: true));
-    dartdocOptionSetArgs.add(DartdocOptionArgOnly<String>('singleFile', 'hello',
+    dartdocOptionSetArgs.add(DartdocOptionArgOnly<String>(
+        'singleFile', 'hello', resourceProvider,
         isFile: true, mustExist: true));
     dartdocOptionSetArgs.add(DartdocOptionArgOnly<String>(
-        'unimportantFile', 'whatever',
+        'unimportantFile', 'whatever', resourceProvider,
         isFile: true));
 
-    dartdocOptionSetAll = DartdocOptionSet('dartdoc');
-    dartdocOptionSetAll
-        .add(DartdocOptionArgFile<List<String>>('categoryOrder', []));
-    dartdocOptionSetAll.add(DartdocOptionArgFile<int>('mySpecialInteger', 91));
-    dartdocOptionSetAll.add(DartdocOptionSet('warn')
-      ..addAll([DartdocOptionArgFile<bool>('unrecognizedVegetable', false)]));
+    dartdocOptionSetAll = DartdocOptionSet('dartdoc', resourceProvider);
+    dartdocOptionSetAll.add(DartdocOptionArgFile<List<String>>(
+        'categoryOrder', [], resourceProvider));
+    dartdocOptionSetAll.add(
+        DartdocOptionArgFile<int>('mySpecialInteger', 91, resourceProvider));
+    dartdocOptionSetAll.add(DartdocOptionSet('warn', resourceProvider)
+      ..addAll([
+        DartdocOptionArgFile<bool>(
+            'unrecognizedVegetable', false, resourceProvider)
+      ]));
     dartdocOptionSetAll.add(DartdocOptionArgFile<Map<String, String>>(
-        'mapOption', {'hi': 'there'}));
-    dartdocOptionSetAll
-        .add(DartdocOptionArgFile<String>('notInAnyFile', 'so there'));
-    dartdocOptionSetAll.add(DartdocOptionArgFile<String>('fileOption', null,
+        'mapOption', {'hi': 'there'}, resourceProvider));
+    dartdocOptionSetAll.add(DartdocOptionArgFile<String>(
+        'notInAnyFile', 'so there', resourceProvider));
+    dartdocOptionSetAll.add(DartdocOptionArgFile<String>(
+        'fileOption', null, resourceProvider,
         isFile: true, mustExist: true));
 
-    tempDir = Directory.systemTemp.createTempSync('options_test');
-    firstDir = Directory(path.join(tempDir.path, 'firstDir'))..createSync();
-    firstExisting = File(path.join(firstDir.path, 'existing.dart'))
-      ..createSync();
-    secondDir = Directory(path.join(tempDir.path, 'secondDir'))..createSync();
-    File(path.join(secondDir.path, 'existing.dart'))..createSync();
-
-    secondDirFirstSub = Directory(path.join(secondDir.path, 'firstSub'))
-      ..createSync();
-    secondDirSecondSub = Directory(path.join(secondDir.path, 'secondSub'))
-      ..createSync();
-
-    dartdocOptionsOne = File(path.join(firstDir.path, 'dartdoc_options.yaml'));
-    dartdocOptionsTwo = File(path.join(secondDir.path, 'dartdoc_options.yaml'));
-    dartdocOptionsTwoFirstSub =
-        File(path.join(secondDirFirstSub.path, 'dartdoc_options.yaml'));
+    tempDir = resourceProvider.createSystemTemp('options_test');
+    firstDir = resourceProvider
+        .getFolder(resourceProvider.pathContext.join(tempDir.path, 'firstDir'))
+          ..create();
+    firstExisting = resourceProvider.getFile(
+        resourceProvider.pathContext.join(firstDir.path, 'existing.dart'))
+      ..writeAsStringSync('');
+    secondDir = resourceProvider
+        .getFolder(resourceProvider.pathContext.join(tempDir.path, 'secondDir'))
+          ..create();
+    resourceProvider.getFile(
+        resourceProvider.pathContext.join(secondDir.path, 'existing.dart'))
+      ..writeAsStringSync('');
+
+    secondDirFirstSub = resourceProvider.getFolder(
+        resourceProvider.pathContext.join(secondDir.path, 'firstSub'))
+      ..create();
+    secondDirSecondSub = resourceProvider.getFolder(
+        resourceProvider.pathContext.join(secondDir.path, 'secondSub'))
+      ..create();
+
+    dartdocOptionsOne = resourceProvider.getFile(resourceProvider.pathContext
+        .join(firstDir.path, 'dartdoc_options.yaml'));
+    dartdocOptionsTwo = resourceProvider.getFile(resourceProvider.pathContext
+        .join(secondDir.path, 'dartdoc_options.yaml'));
+    dartdocOptionsTwoFirstSub = resourceProvider.getFile(resourceProvider
+        .pathContext
+        .join(secondDirFirstSub.path, 'dartdoc_options.yaml'));
 
     dartdocOptionsOne.writeAsStringSync('''
 dartdoc:
@@ -202,7 +232,7 @@ dartdoc:
   });
 
   tearDownAll(() {
-    tempDir.deleteSync(recursive: true);
+    tempDir.delete();
   });
 
   group('new style synthetic option', () {
@@ -230,10 +260,15 @@ dartdoc:
       } on DartdocFileMissing catch (e) {
         errorMessage = e.message;
       }
+      var missingPath = resourceProvider.pathContext.canonicalize(
+          resourceProvider.pathContext.join(
+              resourceProvider.pathContext.absolute(tempDir.path),
+              'existing.dart'));
       expect(
           errorMessage,
-          equals(
-              'Synthetic configuration option vegetableLoaderChecked from <internal>, computed as [existing.dart], resolves to missing path: "${path.canonicalize(path.join(tempDir.absolute.path, 'existing.dart'))}"'));
+          equals('Synthetic configuration option vegetableLoaderChecked from '
+              '<internal>, computed as [existing.dart], resolves to missing '
+              'path: "$missingPath"'));
     });
 
     test('file can override synthetic in FileSynth', () {
@@ -249,8 +284,7 @@ dartdoc:
       // Since this is an ArgSynth, it ignores the yaml option and resolves to the CWD
       expect(
           dartdocOptionSetSynthetic['nonCriticalFileOption'].valueAt(firstDir),
-          equals(path
-              .canonicalize(path.join(Directory.current.path, 'stuff.zip'))));
+          equals(resourceProvider.pathContext.canonicalize('stuff.zip')));
     });
 
     test('ArgSynth defaults to synthetic', () {
@@ -274,10 +308,14 @@ dartdoc:
       } on DartdocFileMissing catch (e) {
         errorMessage = e.message;
       }
+      var missingPath = resourceProvider.pathContext.join(
+          resourceProvider.pathContext
+              .canonicalize(resourceProvider.pathContext.current),
+          'override-not-existing.dart');
       expect(
           errorMessage,
-          equals(
-              'Argument --file-option, set to override-not-existing.dart, resolves to missing path: "${path.join(path.canonicalize(Directory.current.path), "override-not-existing.dart")}"'));
+          equals('Argument --file-option, set to override-not-existing.dart, '
+              'resolves to missing path: "$missingPath"'));
     });
 
     test('validate argument can override missing file', () {
@@ -367,18 +405,21 @@ dartdoc:
       } on DartdocFileMissing catch (e) {
         errorMessage = e.message;
       }
+      var missingPath = resourceProvider.pathContext.join(
+          resourceProvider.pathContext
+              .canonicalize(resourceProvider.pathContext.current),
+          'not_found.txt');
       expect(
           errorMessage,
-          equals(
-              'Argument --single-file, set to not_found.txt, resolves to missing path: '
-              '"${path.join(path.canonicalize(Directory.current.path), 'not_found.txt')}"'));
+          equals('Argument --single-file, set to not_found.txt, resolves to '
+              'missing path: "$missingPath"'));
     });
 
     test('DartdocOptionArgOnly checks file existence on multi-options', () {
       String errorMessage;
       dartdocOptionSetArgs.parseArguments([
         '--files-flag',
-        firstExisting.absolute.path,
+        resourceProvider.pathContext.absolute(firstExisting.path),
         '--files-flag',
         'other_not_found.txt'
       ]);
@@ -387,11 +428,16 @@ dartdoc:
       } on DartdocFileMissing catch (e) {
         errorMessage = e.message;
       }
+      var missingPath = resourceProvider.pathContext.join(
+          resourceProvider.pathContext
+              .canonicalize(resourceProvider.pathContext.current),
+          'other_not_found.txt');
       expect(
           errorMessage,
-          equals(
-              'Argument --files-flag, set to [${firstExisting.absolute.path}, other_not_found.txt], resolves to missing path: '
-              '"${path.join(path.canonicalize(Directory.current.path), "other_not_found.txt")}"'));
+          equals('Argument --files-flag, set to '
+              '[${resourceProvider.pathContext.absolute(firstExisting.path)}, '
+              'other_not_found.txt], resolves to missing path: '
+              '"$missingPath"'));
     });
 
     test(
@@ -401,7 +447,9 @@ dartdoc:
           .parseArguments(['--unimportant-file', 'this-will-never-exist']);
       expect(
           dartdocOptionSetArgs['unimportantFile'].valueAt(tempDir),
-          equals(path.join(path.canonicalize(Directory.current.path),
+          equals(resourceProvider.pathContext.join(
+              resourceProvider.pathContext
+                  .canonicalize(resourceProvider.pathContext.current),
               'this-will-never-exist')));
     });
 
diff --git a/test/dartdoc_test.dart b/test/dartdoc_test.dart
index fac044c10f..d466973b7c 100644
--- a/test/dartdoc_test.dart
+++ b/test/dartdoc_test.dart
@@ -5,9 +5,11 @@
 library dartdoc.dartdoc_test;
 
 import 'dart:async';
-import 'dart:io';
+import 'dart:io' show Platform;
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/dartdoc.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/logging.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:dartdoc/src/tuple.dart';
@@ -17,67 +19,86 @@ import 'package:test/test.dart';
 
 import 'src/utils.dart';
 
-final Directory _testPackageDir = Directory('testing/test_package');
-
-final _testPackageBadDir = Directory('testing/test_package_bad');
-final _testPackageMinimumDir = Directory('testing/test_package_minimum');
-final _testSkyEnginePackage = Directory('testing/sky_engine');
-final _testPackageWithNoReadme = Directory('testing/test_package_small');
-final _testPackageIncludeExclude =
-    Directory('testing/test_package_include_exclude');
-final _testPackageImportExportError =
-    Directory('testing/test_package_import_export_error');
-final _testPackageOptions = Directory('testing/test_package_options');
-final _testPackageOptionsImporter =
-    Directory('testing/test_package_options_importer');
+final _resourceProvider = pubPackageMetaProvider.resourceProvider;
+final _pathContext = _resourceProvider.pathContext;
+
+Folder _getFolder(String p) => _resourceProvider
+    .getFolder(_pathContext.absolute(_pathContext.canonicalize(p)));
+
+final _testPackageDir = _getFolder('testing/test_package');
+
+final Folder _testPackageBadDir = _getFolder('testing/test_package_bad');
+final Folder _testPackageMinimumDir =
+    _getFolder('testing/test_package_minimum');
+final Folder _testSkyEnginePackage = _getFolder('testing/sky_engine');
+final Folder _testPackageWithNoReadme =
+    _getFolder('testing/test_package_small');
+final Folder _testPackageIncludeExclude =
+    _getFolder('testing/test_package_include_exclude');
+final Folder _testPackageImportExportError =
+    _getFolder('testing/test_package_import_export_error');
+final Folder _testPackageOptions = _getFolder('testing/test_package_options');
+final Folder _testPackageOptionsImporter =
+    _getFolder('testing/test_package_options_importer');
 final _testPackageCustomTemplates =
-    Directory('testing/test_package_custom_templates');
+    _getFolder('testing/test_package_custom_templates');
 
 /// Convenience factory to build a [DartdocGeneratorOptionContext] and associate
 /// it with a [DartdocOptionSet] based on the current working directory and/or
 /// the '--input' flag.
 Future<DartdocGeneratorOptionContext> _generatorContextFromArgv(
     List<String> argv) async {
-  var optionSet = await DartdocOptionSet.fromOptionGenerators('dartdoc', [
-    () => createDartdocOptions(pubPackageMetaProvider),
-    createGeneratorOptions,
-  ]);
+  var optionSet = await DartdocOptionSet.fromOptionGenerators(
+      'dartdoc',
+      [
+        createDartdocOptions,
+        createGeneratorOptions,
+      ],
+      pubPackageMetaProvider);
   optionSet.parseArguments(argv);
-  return DartdocGeneratorOptionContext(optionSet, null);
+  return DartdocGeneratorOptionContext(
+      optionSet, null, pubPackageMetaProvider.resourceProvider);
 }
 
 class DartdocLoggingOptionContext extends DartdocGeneratorOptionContext
     with LoggingContext {
-  DartdocLoggingOptionContext(DartdocOptionSet optionSet, Directory dir)
-      : super(optionSet, dir);
+  DartdocLoggingOptionContext(
+      DartdocOptionSet optionSet, Folder dir, ResourceProvider resourceProvider)
+      : super(optionSet, dir, resourceProvider);
 }
 
 void main() {
   group('dartdoc with generators', () {
-    Directory tempDir;
+    var resourceProvider = pubPackageMetaProvider.resourceProvider;
+    Folder tempDir;
 
     setUpAll(() async {
+      //resourceProvider = MemoryResourceProvider();
       var optionSet = await DartdocOptionSet.fromOptionGenerators(
-          'dartdoc', [createLoggingOptions]);
+          'dartdoc', [createLoggingOptions], pubPackageMetaProvider);
       optionSet.parseArguments([]);
-      startLogging(DartdocLoggingOptionContext(optionSet, Directory.current));
+      startLogging(DartdocLoggingOptionContext(
+          optionSet,
+          resourceProvider.getFolder(resourceProvider.pathContext.current),
+          resourceProvider));
     });
 
     setUp(() async {
-      tempDir = Directory.systemTemp.createTempSync('dartdoc.test.');
+      tempDir = resourceProvider.createSystemTemp('dartdoc.test.');
     });
 
     tearDown(() async {
-      tempDir.deleteSync(recursive: true);
+      tempDir.delete();
     });
 
     Future<Dartdoc> buildDartdoc(
-        List<String> argv, Directory packageRoot, Directory tempDir) async {
+        List<String> argv, Folder packageRoot, Folder tempDir) async {
       var context = await _generatorContextFromArgv(argv
         ..addAll(['--input', packageRoot.path, '--output', tempDir.path]));
+
       return await Dartdoc.fromContext(
         context,
-        PubPackageBuilder(context),
+        PubPackageBuilder(context, pubPackageMetaProvider),
       );
     }
 
@@ -85,19 +106,20 @@ void main() {
       Dartdoc dartdoc;
       DartdocResults results;
       PackageGraph p;
-      Directory tempDir;
+      Folder tempDir;
 
       setUpAll(() async {
-        tempDir = Directory.systemTemp.createTempSync('dartdoc.test.');
+        tempDir = resourceProvider.createSystemTemp('dartdoc.test.');
         dartdoc = await buildDartdoc([], _testPackageOptions, tempDir);
         results = await dartdoc.generateDocsBase();
         p = results.packageGraph;
       });
 
       test('generator parameters', () async {
-        var favicon =
-            File(path.joinAll([tempDir.path, 'static-assets', 'favicon.png']));
-        var index = File(path.joinAll([tempDir.path, 'index.html']));
+        var favicon = resourceProvider.getFile(resourceProvider.pathContext
+            .joinAll([tempDir.path, 'static-assets', 'favicon.png']));
+        var index = resourceProvider.getFile(
+            resourceProvider.pathContext.joinAll([tempDir.path, 'index.html']));
         expect(favicon.readAsStringSync(),
             contains('Not really a png, but a test file'));
         var indexString = index.readAsStringSync();
@@ -145,10 +167,10 @@ void main() {
     group('Option handling with cross-linking', () {
       DartdocResults results;
       Package testPackageOptions;
-      Directory tempDir;
+      Folder tempDir;
 
       setUpAll(() async {
-        tempDir = Directory.systemTemp.createTempSync('dartdoc.test.');
+        tempDir = resourceProvider.createSystemTemp('dartdoc.test.');
         results = await (await buildDartdoc(
                 ['--link-to-remote'], _testPackageOptionsImporter, tempDir))
             .generateDocsBase();
@@ -259,10 +281,10 @@ void main() {
     group('validate basic doc generation', () {
       Dartdoc dartdoc;
       DartdocResults results;
-      Directory tempDir;
+      Folder tempDir;
 
       setUpAll(() async {
-        tempDir = Directory.systemTemp.createTempSync('dartdoc.test.');
+        tempDir = resourceProvider.createSystemTemp('dartdoc.test.');
         dartdoc = await buildDartdoc([], _testPackageDir, tempDir);
         results = await dartdoc.generateDocs();
       });
@@ -284,13 +306,15 @@ void main() {
       test('source code links are visible', () async {
         // Picked this object as this library explicitly should never contain
         // a library directive, so we can predict what line number it will be.
-        var anonymousOutput = File(path.join(tempDir.path, 'anonymous_library',
-            'anonymous_library-library.html'));
-        expect(anonymousOutput.existsSync(), isTrue);
+        var anonymousOutput = resourceProvider.getFile(
+            resourceProvider.pathContext.join(tempDir.path, 'anonymous_library',
+                'anonymous_library-library.html'));
+        expect(anonymousOutput.exists, isTrue);
         expect(
             anonymousOutput.readAsStringSync(),
-            contains(
-                r'<a title="View source code" class="source-link" href="https://github.com/dart-lang/dartdoc/blob/master/testing/test_package/lib/anonymous_library.dart#L1"><i class="material-icons">description</i></a>'));
+            contains(r'<a title="View source code" class="source-link" '
+                'href="https://github.com/dart-lang/dartdoc/blob/master/testing/test_package/lib/anonymous_library.dart#L1">'
+                '<i class="material-icons">description</i></a>'));
       });
     });
 
@@ -397,7 +421,8 @@ void main() {
       expect(p.defaultPackage.name, 'test_package_custom_templates');
       expect(p.localPublicLibraries, hasLength(1));
 
-      var index = File(path.join(tempDir.path, 'index.html'));
+      var index = resourceProvider.getFile(
+          resourceProvider.pathContext.join(tempDir.path, 'index.html'));
       expect(index.readAsStringSync(),
           contains('Welcome my friends to a custom template'));
     });
@@ -440,14 +465,16 @@ void main() {
       await dartdoc.generateDocsBase();
 
       // Verify files at different levels have correct <link> content.
-      var level1 = File(path.join(tempDir.path, 'ex', 'Apple-class.html'));
-      expect(level1.existsSync(), isTrue);
+      var level1 = resourceProvider.getFile(resourceProvider.pathContext
+          .join(tempDir.path, 'ex', 'Apple-class.html'));
+      expect(level1.exists, isTrue);
       expect(
           level1.readAsStringSync(),
           contains(
               '<link rel="canonical" href="$prefix/ex/Apple-class.html">'));
-      var level2 = File(path.join(tempDir.path, 'ex', 'Apple', 'm.html'));
-      expect(level2.existsSync(), isTrue);
+      var level2 = resourceProvider.getFile(resourceProvider.pathContext
+          .join(tempDir.path, 'ex', 'Apple', 'm.html'));
+      expect(level2.exists, isTrue);
       expect(level2.readAsStringSync(),
           contains('<link rel="canonical" href="$prefix/ex/Apple/m.html">'));
     });
diff --git a/test/html_generator_test.dart b/test/html_generator_test.dart
index 567fa3accd..0a55d1c217 100644
--- a/test/html_generator_test.dart
+++ b/test/html_generator_test.dart
@@ -4,14 +4,14 @@
 
 library dartdoc.html_generator_test;
 
-import 'dart:io' show File, FileSystemEntity, Directory;
-
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/generator/generator_frontend.dart';
 import 'package:dartdoc/src/generator/html_generator.dart';
 import 'package:dartdoc/src/generator/html_resources.g.dart';
 import 'package:dartdoc/src/generator/templates.dart';
 import 'package:dartdoc/src/model/package_graph.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/warnings.dart';
 import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
@@ -75,54 +75,58 @@ void main() {
   });
 
   group('HtmlGenerator', () {
+    Generator generator;
+    var resourceProvider = pubPackageMetaProvider.resourceProvider;
+    var pathContext = resourceProvider.pathContext;
+    Folder tempOutput;
+    FileWriter writer;
+
     // TODO: Run the HtmlGenerator and validate important constraints.
     group('for a null package', () {
-      Generator generator;
-      Directory tempOutput;
-      FileWriter writer;
-
       setUp(() async {
         generator = await _initGeneratorForTest();
-        tempOutput = Directory.systemTemp.createTempSync('doc_test_temp');
-        writer = DartdocFileWriter(tempOutput.path);
+        tempOutput = resourceProvider.createSystemTemp('doc_test_temp');
+        writer = DartdocFileWriter(tempOutput.path, resourceProvider);
         return generator.generate(null, writer);
       });
 
       tearDown(() {
         if (tempOutput != null) {
-          tempOutput.deleteSync(recursive: true);
+          tempOutput.delete();
         }
       });
 
       test('resources are put into the right place', () {
-        var output = Directory(path.join(tempOutput.path, 'static-assets'));
+        var output = resourceProvider
+            .getFolder(pathContext.join(tempOutput.path, 'static-assets'));
         expect(output, doesExist);
 
         for (var resource in resource_names.map((r) =>
             path.relative(Uri.parse(r).path, from: 'dartdoc/resources'))) {
-          expect(File(path.join(output.path, resource)), doesExist);
+          expect(
+              resourceProvider.getFile(pathContext.join(output.path, resource)),
+              doesExist);
         }
       });
     });
 
     group('for a package that causes duplicate files', () {
-      Generator generator;
       PackageGraph packageGraph;
-      Directory tempOutput;
-      FileWriter writer;
-      var testPackageDuplicateDir = Directory('testing/test_package_duplicate');
+      var testPackageDuplicateDir = resourceProvider.getFolder(
+          pathContext.absolute(
+              pathContext.canonicalize('testing/test_package_duplicate')));
 
       setUp(() async {
         generator = await _initGeneratorForTest();
-        packageGraph =
-            await utils.bootBasicPackage(testPackageDuplicateDir.path, []);
-        tempOutput = await Directory.systemTemp.createTemp('doc_test_temp');
-        writer = DartdocFileWriter(tempOutput.path);
+        packageGraph = await utils.bootBasicPackage(
+            testPackageDuplicateDir.path, [], pubPackageMetaProvider);
+        tempOutput = await resourceProvider.createSystemTemp('doc_test_temp');
+        writer = DartdocFileWriter(tempOutput.path, resourceProvider);
       });
 
       tearDown(() {
         if (tempOutput != null) {
-          tempOutput.deleteSync(recursive: true);
+          tempOutput.delete();
         }
       });
 
@@ -145,14 +149,13 @@ const Matcher doesExist = _DoesExist();
 class _DoesExist extends Matcher {
   const _DoesExist();
   @override
-  bool matches(dynamic item, Map matchState) =>
-      (item as FileSystemEntity).existsSync();
+  bool matches(dynamic item, Map matchState) => (item as Resource).exists;
   @override
   Description describe(Description description) => description.add('exists');
   @override
   Description describeMismatch(dynamic item, Description mismatchDescription,
       Map matchState, bool verbose) {
-    if (item is! File && item is! Directory) {
+    if (item is! File && item is! Folder) {
       return mismatchDescription
           .addDescriptionOf(item)
           .add('is not a file or directory');
diff --git a/test/model_special_cases_test.dart b/test/model_special_cases_test.dart
index 73b80b7a0a..3000bc24c8 100644
--- a/test/model_special_cases_test.dart
+++ b/test/model_special_cases_test.dart
@@ -12,7 +12,9 @@ import 'dart:io';
 
 import 'package:async/async.dart';
 import 'package:dartdoc/dartdoc.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/model/model.dart';
+import 'package:dartdoc/src/package_meta.dart';
 import 'package:dartdoc/src/special_elements.dart';
 import 'package:pub_semver/pub_semver.dart';
 import 'package:test/test.dart';
@@ -25,7 +27,8 @@ final Version _platformVersion = Version.parse(_platformVersionString);
 final _testPackageGraphExperimentsMemo = AsyncMemoizer<PackageGraph>();
 Future<PackageGraph> get _testPackageGraphExperiments =>
     _testPackageGraphExperimentsMemo.runOnce(() => utils.bootBasicPackage(
-            'testing/test_package_experiments', [], additionalArguments: [
+        'testing/test_package_experiments', [], pubPackageMetaProvider,
+        additionalArguments: [
           '--enable-experiment',
           'non-nullable',
           '--no-link-to-remote'
@@ -34,11 +37,10 @@ Future<PackageGraph> get _testPackageGraphExperiments =>
 final _testPackageGraphGinormousMemo = AsyncMemoizer<PackageGraph>();
 Future<PackageGraph> get _testPackageGraphGinormous =>
     _testPackageGraphGinormousMemo.runOnce(() => utils.bootBasicPackage(
-            'testing/test_package', [
-          'css',
-          'code_in_commnets',
-          'excluded'
-        ], additionalArguments: [
+        'testing/test_package',
+        ['css', 'code_in_commnets', 'excluded'],
+        pubPackageMetaProvider,
+        additionalArguments: [
           '--auto-include-dependencies',
           '--no-link-to-remote'
         ]));
@@ -46,7 +48,7 @@ Future<PackageGraph> get _testPackageGraphGinormous =>
 final _testPackageGraphSmallMemo = AsyncMemoizer<PackageGraph>();
 Future<PackageGraph> get _testPackageGraphSmall =>
     _testPackageGraphSmallMemo.runOnce(() => utils.bootBasicPackage(
-        'testing/test_package_small', [],
+        'testing/test_package_small', [], pubPackageMetaProvider,
         additionalArguments: ['--no-link-to-remote']));
 
 final _testPackageGraphSdkMemo = AsyncMemoizer<PackageGraph>();
@@ -55,12 +57,16 @@ Future<PackageGraph> get _testPackageGraphSdk =>
 
 Future<PackageGraph> _bootSdkPackage() async {
   return PubPackageBuilder(
-          await utils.contextFromArgv(['--input', defaultSdkDir.path]))
+          await utils.contextFromArgv([
+            '--input',
+            pubPackageMetaProvider.resourceProvider.defaultSdkDir.path
+          ], pubPackageMetaProvider),
+          pubPackageMetaProvider)
       .buildPackageGraph();
 }
 
 void main() {
-  var sdkDir = defaultSdkDir;
+  var sdkDir = pubPackageMetaProvider.resourceProvider.defaultSdkDir;
 
   if (sdkDir == null) {
     print('Warning: unable to locate the Dart SDK.');
@@ -256,7 +262,9 @@ void main() {
 
     setUpAll(() async {
       injectionPackageGraph = await utils.bootBasicPackage(
-          'testing/test_package', ['css', 'code_in_comments', 'excluded'],
+          'testing/test_package',
+          ['css', 'code_in_comments', 'excluded'],
+          pubPackageMetaProvider,
           additionalArguments: ['--inject-html']);
 
       injectionExLibrary =
diff --git a/test/model_test.dart b/test/model_test.dart
index 88c37b5e21..7d70c12413 100644
--- a/test/model_test.dart
+++ b/test/model_test.dart
@@ -8,6 +8,7 @@ import 'dart:io';
 
 import 'package:async/async.dart';
 import 'package:dartdoc/dartdoc.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/model/model.dart';
 import 'package:dartdoc/src/render/category_renderer.dart';
 import 'package:dartdoc/src/render/enum_field_renderer.dart';
@@ -23,7 +24,9 @@ import 'src/utils.dart' as utils;
 final _testPackageGraphMemo = AsyncMemoizer<PackageGraph>();
 Future<PackageGraph> get _testPackageGraph =>
     _testPackageGraphMemo.runOnce(() => utils.bootBasicPackage(
-        'testing/test_package', ['css', 'code_in_comments'],
+        'testing/test_package',
+        ['css', 'code_in_comments'],
+        pubPackageMetaProvider,
         additionalArguments: ['--no-link-to-remote']));
 
 /// For testing sort behavior.
@@ -56,7 +59,7 @@ class TestLibraryContainerSdk extends TestLibraryContainer {
 }
 
 void main() {
-  var sdkDir = defaultSdkDir;
+  var sdkDir = pubPackageMetaProvider.resourceProvider.defaultSdkDir;
 
   if (sdkDir == null) {
     print('Warning: unable to locate the Dart SDK.');
diff --git a/test/package_meta_test.dart b/test/package_meta_test.dart
index 4e4295a0f2..377bf198e9 100644
--- a/test/package_meta_test.dart
+++ b/test/package_meta_test.dart
@@ -4,18 +4,18 @@
 
 library dartdoc.package_utils_test;
 
-import 'dart:io';
-
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/package_meta.dart';
-import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
 void main() {
+  var resourceProvider = pubPackageMetaProvider.resourceProvider;
+
   group('PackageMeta for a directory without a pubspec', () {
     PackageMeta p;
 
     setUp(() {
-      var d = Directory.systemTemp.createTempSync('test_package_not_valid');
+      var d = resourceProvider.createSystemTemp('test_package_not_valid');
       p = pubPackageMetaProvider.fromDir(d);
     });
 
@@ -25,17 +25,27 @@ void main() {
   });
 
   group('PackageMeta for the test package', () {
-    var p = pubPackageMetaProvider.fromDir(Directory(
-        path.join(Directory.current.path, 'testing', 'test_package')));
+    PackageMeta p;
+
+    setUp(() {
+      p = pubPackageMetaProvider.fromDir(resourceProvider.getFolder(
+          resourceProvider.pathContext.join(
+              resourceProvider.pathContext.current,
+              'testing',
+              'test_package')));
+    });
 
     test('readme with corrupt UTF-8 loads without throwing', () {
-      expect(p.getReadmeContents().contents,
+      expect(
+          resourceProvider
+              .readAsMalformedAllowedStringSync(p.getReadmeContents()),
           contains('Here is some messed up UTF-8.\nÐf'));
     });
   });
 
   group('PackageMeta.fromDir for this package', () {
-    var p = pubPackageMetaProvider.fromDir(Directory.current);
+    var p = pubPackageMetaProvider.fromDir(
+        resourceProvider.getFolder(resourceProvider.pathContext.current));
 
     test('has a name', () {
       expect(p.name, 'dartdoc');
@@ -64,25 +74,31 @@ void main() {
     test('has a readme', () {
       expect(p.getReadmeContents(), isNotNull);
       expect(
-          p.getReadmeContents().contents,
+          resourceProvider
+              .readAsMalformedAllowedStringSync(p.getReadmeContents()),
           contains(
               'Use `dartdoc` to generate HTML documentaton for your Dart package.'));
     });
 
     test('has a license', () {
       expect(p.getLicenseContents(), isNotNull);
-      expect(p.getLicenseContents().contents,
+      expect(
+          resourceProvider
+              .readAsMalformedAllowedStringSync(p.getLicenseContents()),
           contains('Copyright 2014, the Dart project authors.'));
     });
 
     test('has a changelog', () {
       expect(p.getChangelogContents(), isNotNull);
-      expect(p.getChangelogContents().contents, contains('## 0.2.2'));
+      expect(
+          resourceProvider
+              .readAsMalformedAllowedStringSync(p.getChangelogContents()),
+          contains('## 0.2.2'));
     });
   });
 
   group('PackageMeta.fromSdk', () {
-    var p = pubPackageMetaProvider.fromDir(defaultSdkDir);
+    var p = pubPackageMetaProvider.fromDir(resourceProvider.defaultSdkDir);
 
     test('has a name', () {
       expect(p.name, 'Dart');
@@ -111,7 +127,10 @@ void main() {
 
     test('has a readme', () {
       expect(p.getReadmeContents(), isNotNull);
-      expect(p.getReadmeContents().contents, startsWith('Welcome'));
+      expect(
+          resourceProvider
+              .readAsMalformedAllowedStringSync(p.getReadmeContents()),
+          startsWith('Welcome'));
     });
 
     test('does not have a license', () {
diff --git a/test/src/utils.dart b/test/src/utils.dart
index 6628fe9074..58334b29ae 100644
--- a/test/src/utils.dart
+++ b/test/src/utils.dart
@@ -5,10 +5,10 @@
 library test_utils;
 
 import 'dart:async';
-import 'dart:io';
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:dartdoc/dartdoc.dart';
-import 'package:dartdoc/src/model/model.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/package_meta.dart';
 
 /// The number of public libraries in testing/test_package, minus 2 for
@@ -16,33 +16,44 @@ import 'package:dartdoc/src/package_meta.dart';
 /// and minus 1 for the <nodoc> tag in the 'excluded' library.
 const int kTestPackagePublicLibraries = 17;
 
-final Directory testPackageToolError =
-    Directory('testing/test_package_tool_error');
+final _resourceProvider = pubPackageMetaProvider.resourceProvider;
+final _pathContext = _resourceProvider.pathContext;
+
+final Folder testPackageToolError = _resourceProvider.getFolder(_pathContext
+    .absolute(_pathContext.normalize('testing/test_package_tool_error')));
 
 /// Convenience factory to build a [DartdocOptionContext] and associate it with a
 /// [DartdocOptionSet] based on the current working directory.
-Future<DartdocOptionContext> contextFromArgv(List<String> argv) async {
-  var optionSet = await DartdocOptionSet.fromOptionGenerators('dartdoc', [
-    () => createDartdocOptions(pubPackageMetaProvider),
-  ]);
+Future<DartdocOptionContext> contextFromArgv(
+    List<String> argv, PackageMetaProvider packageMetaProvider) async {
+  var resourceProvider = packageMetaProvider.resourceProvider;
+  var optionSet = await DartdocOptionSet.fromOptionGenerators(
+      'dartdoc', [createDartdocOptions], packageMetaProvider);
   optionSet.parseArguments(argv);
-  return DartdocOptionContext(optionSet, Directory.current);
+  return DartdocOptionContext(
+      optionSet,
+      resourceProvider.getFolder(resourceProvider.pathContext.current),
+      pubPackageMetaProvider.resourceProvider);
 }
 
-Future<PackageGraph> bootBasicPackage(
-    String dirPath, List<String> excludeLibraries,
+Future<PackageGraph> bootBasicPackage(String dirPath,
+    List<String> excludeLibraries, PackageMetaProvider packageMetaProvider,
     {List<String> additionalArguments}) async {
-  var dir = Directory(dirPath);
+  var resourceProvider = packageMetaProvider.resourceProvider;
+  var dir = resourceProvider.getFolder(resourceProvider.pathContext
+      .absolute(resourceProvider.pathContext.normalize(dirPath)));
   additionalArguments ??= <String>[];
-  return PubPackageBuilder(await contextFromArgv([
+  return PubPackageBuilder(
+          await contextFromArgv([
             '--input',
             dir.path,
             '--sdk-dir',
-            defaultSdkDir.path,
+            resourceProvider.defaultSdkDir.path,
             '--exclude',
             excludeLibraries.join(','),
             '--allow-tools',
-          ] +
-          additionalArguments))
+            ...additionalArguments,
+          ], packageMetaProvider),
+          packageMetaProvider)
       .buildPackageGraph();
 }
diff --git a/test/tool_runner_test.dart b/test/tool_runner_test.dart
index d378acdd5e..34ac28a5d5 100644
--- a/test/tool_runner_test.dart
+++ b/test/tool_runner_test.dart
@@ -6,6 +6,7 @@ library dartdoc.model_test;
 
 import 'dart:io';
 
+import 'package:dartdoc/dartdoc.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/tool_runner.dart';
 import 'package:path/path.dart' as path;
@@ -36,7 +37,8 @@ void main() {
             '--snapshot-kind=app-jit',
             'bin/drill.dart'
           ],
-          workingDirectory: _testPackageDir.absolute.path);
+          workingDirectory: pubPackageMetaProvider.resourceProvider.pathContext
+              .absolute(_testPackageDir.path));
     } on ProcessException catch (exception) {
       stderr.writeln('Unable to make snapshot of tool: $exception');
       expect(result?.exitCode, equals(0));
@@ -73,8 +75,11 @@ echo:
   windows: ['C:\\Windows\\System32\\cmd.exe', '/c', 'echo']
   description: 'Works on everything'
 ''';
-    var pathContext = path.Context(current: _testPackageDir.absolute.path);
-    toolMap = ToolConfiguration.fromYamlMap(loadYaml(yamlMap), pathContext);
+    toolMap = ToolConfiguration.fromYamlMap(
+        loadYaml(yamlMap),
+        pubPackageMetaProvider.resourceProvider.pathContext
+            .absolute(_testPackageDir.path),
+        pubPackageMetaProvider.resourceProvider);
     // This shouldn't really happen, but if you didn't load the config from a
     // yaml map (which would fail on a missing executable), or a file is deleted
     // during execution,it might, so we test it.
@@ -88,7 +93,7 @@ echo:
   tearDownAll(() {
     tempDir?.deleteSync(recursive: true);
     tracker?.dispose();
-    SnapshotCache.instance.dispose();
+    SnapshotCache.instance?.dispose();
     setupFile = null;
     tempDir = null;
   });
diff --git a/test/unit/comment_processable_test.dart b/test/unit/comment_processable_test.dart
index 7aafa2445c..15e3a4ca34 100644
--- a/test/unit/comment_processable_test.dart
+++ b/test/unit/comment_processable_test.dart
@@ -2,9 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:io' show Directory;
-
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
 import 'package:dartdoc/src/model/model.dart';
@@ -320,10 +320,10 @@ End text.'''));
 ///
 /// End text.
 ''');
-    verify(processor.packageGraph.warnOnElement(
-            processor, PackageWarning.missingExampleFile,
-            message:
-                '${p.join(_projectRoot, 'abc.md')}; path listed at a.dart'))
+    verify(processor.packageGraph
+            .warnOnElement(processor, PackageWarning.missingExampleFile,
+                message: '${p.canonicalize(p.join(_projectRoot, 'abc.md'))}; '
+                    'path listed at a.dart'))
         .called(1);
     // When the example path is invalid, the directive should be left in-place.
     expect(doc, equals('''
@@ -346,7 +346,8 @@ End text.'''));
     verify(processor.packageGraph.warnOnElement(
             processor, PackageWarning.missingExampleFile,
             message:
-                '${p.join(_projectRoot, 'abc', 'def', 'ghi.md')}; path listed at a.dart'))
+                '${p.canonicalize(p.join(_projectRoot, 'abc', 'def', 'ghi.md'))}; '
+                'path listed at a.dart'))
         .called(1);
     // When the example path is invalid, the directive should be left in-place.
     expect(doc, equals('''
@@ -366,10 +367,10 @@ End text.'''));
 ///
 /// End text.
 ''');
-    verify(processor.packageGraph.warnOnElement(
-            processor, PackageWarning.missingExampleFile,
-            message:
-                '${p.join(_projectRoot, '.', 'abc-r.md')}; path listed at a.dart'))
+    verify(processor.packageGraph
+            .warnOnElement(processor, PackageWarning.missingExampleFile,
+                message: '${p.canonicalize(p.join(_projectRoot, 'abc-r.md'))}; '
+                    'path listed at a.dart'))
         .called(1);
     // When the example path is invalid, the directive should be left in-place.
     expect(doc, equals('''
@@ -564,6 +565,7 @@ class _Processor extends __Processor with CommentProcessable {
         .thenReturn('<!-- render -->');
     when(modelElementRenderer.renderAnimation(any, any, any, any, any))
         .thenReturn('<!-- render -->');
+    when(packageGraph.resourceProvider).thenReturn(MemoryResourceProvider());
   }
 
   @override
@@ -573,11 +575,11 @@ class _Processor extends __Processor with CommentProcessable {
           message: message, referredFrom: referredFrom);
 }
 
-class _FakeDirectory extends Fake implements Directory {
+class _FakeFolder extends Fake implements Folder {
   @override
   final String path;
 
-  _FakeDirectory() : path = _projectRoot;
+  _FakeFolder() : path = _projectRoot;
 }
 
 class _MockModelElementRenderer extends Mock implements ModelElementRenderer {}
@@ -594,9 +596,9 @@ class _FakePackage extends Fake implements Package {
 
 class _FakePackageMeta extends Fake implements PackageMeta {
   @override
-  final Directory dir;
+  final Folder dir;
 
-  _FakePackageMeta() : dir = _FakeDirectory();
+  _FakePackageMeta() : dir = _FakeFolder();
 }
 
 class _FakeElement extends Fake implements Element {
diff --git a/test/warnings_test.dart b/test/warnings_test.dart
index fc14061663..b4db31ee41 100644
--- a/test/warnings_test.dart
+++ b/test/warnings_test.dart
@@ -5,33 +5,39 @@
 /// Unit tests for lib/src/warnings.dart.
 library dartdoc.warnings_test;
 
-import 'dart:io';
-
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:dartdoc/src/dartdoc_options.dart';
+import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/package_meta.dart';
 import 'package:dartdoc/src/warnings.dart';
-import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
 void main() {
-  Directory tempDir, testPackageOne, testPackageTwo, testPackageThree;
+  ResourceProvider resourceProvider = PhysicalResourceProvider.INSTANCE;
+  Folder tempDir, testPackageOne, testPackageTwo, testPackageThree;
   File pubspecYamlOne, pubspecYamlTwo, pubspecYamlThree, dartdocYamlThree;
   DartdocOptionSet optionSet;
 
   setUpAll(() {
-    tempDir = Directory.systemTemp.createTempSync('warnings_test');
-    testPackageOne = Directory(path.join(tempDir.path, 'test_package_one'))
-      ..createSync();
-    testPackageTwo = Directory(path.join(tempDir.path, 'test_package_two'))
-      ..createSync();
-    testPackageThree = Directory(path.join(tempDir.path, 'test_package_three'))
-      ..createSync();
-    pubspecYamlOne = File(path.join(testPackageOne.path, 'pubspec.yaml'));
+    tempDir = resourceProvider.createSystemTemp('warnings_test');
+    testPackageOne = resourceProvider.getFolder(
+        resourceProvider.pathContext.join(tempDir.path, 'test_package_one'))
+      ..create();
+    testPackageTwo = resourceProvider.getFolder(
+        resourceProvider.pathContext.join(tempDir.path, 'test_package_two'))
+      ..create();
+    testPackageThree = resourceProvider.getFolder(
+        resourceProvider.pathContext.join(tempDir.path, 'test_package_three'))
+      ..create();
+    pubspecYamlOne = resourceProvider.getFile(
+        resourceProvider.pathContext.join(testPackageOne.path, 'pubspec.yaml'));
     pubspecYamlOne.writeAsStringSync('name: test_package_one');
-    pubspecYamlTwo = File(path.join(testPackageTwo.path, 'pubspec.yaml'));
+    pubspecYamlTwo = resourceProvider.getFile(
+        resourceProvider.pathContext.join(testPackageTwo.path, 'pubspec.yaml'));
     pubspecYamlTwo.writeAsStringSync('name: test_package_two');
-    dartdocYamlThree =
-        File(path.join(testPackageThree.path, 'dartdoc_options.yaml'));
+    dartdocYamlThree = resourceProvider.getFile(resourceProvider.pathContext
+        .join(testPackageThree.path, 'dartdoc_options.yaml'));
     dartdocYamlThree.writeAsStringSync('''
 dartdoc:
   warnings:
@@ -42,13 +48,14 @@ dartdoc:
   ignore:
     - ambiguous-reexport  
     ''');
-    pubspecYamlThree = File(path.join(testPackageThree.path, 'pubspec.yaml'));
+    pubspecYamlThree = resourceProvider.getFile(resourceProvider.pathContext
+        .join(testPackageThree.path, 'pubspec.yaml'));
     pubspecYamlThree.writeAsStringSync('name: test_package_three');
   });
 
   setUp(() async {
     optionSet = await DartdocOptionSet.fromOptionGenerators(
-        'dartdoc', [() => createDartdocOptions(pubPackageMetaProvider)]);
+        'dartdoc', [createDartdocOptions], pubPackageMetaProvider);
   });
 
   test('Verify that options for enabling/disabling packages work', () {
diff --git a/tool/grind.dart b/tool/grind.dart
index bb0e98a8b2..19bd395657 100644
--- a/tool/grind.dart
+++ b/tool/grind.dart
@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:io' hide ProcessException;
 
+import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:dartdoc/src/io_utils.dart';
 import 'package:dartdoc/src/package_meta.dart';
 import 'package:grinder/grinder.dart';
@@ -823,7 +824,9 @@ Future<String> _buildPubPackageDocs(
   var pubPackageDir = Directory.systemTemp.createTempSync(pubPackageName);
   await copyPath(pubPackageDirOrig.path, pubPackageDir.path);
 
-  if (packageMetaProvider.fromDir(pubPackageDir).requiresFlutter) {
+  if (packageMetaProvider
+      .fromDir(PhysicalResourceProvider.INSTANCE.getFolder(pubPackageDir.path))
+      .requiresFlutter) {
     var flutterRepo =
         await FlutterRepo.fromExistingFlutterRepo(await cleanFlutterRepo);
     await launcher.runStreamed(flutterRepo.cachePub, ['get'],
@@ -1033,7 +1036,9 @@ Future<void> testDart2(Iterable<File> tests) async {
                 <String>[...parameters, dartFile.path]));
   }
 
-  return CoverageSubprocessLauncher.generateCoverageToFile(File('lcov.info'));
+  return CoverageSubprocessLauncher.generateCoverageToFile(
+      PhysicalResourceProvider.INSTANCE.getFile('lcov.info'),
+      PhysicalResourceProvider.INSTANCE);
 }
 
 @Task('Generate docs for dartdoc without link-to-remote')
diff --git a/tool/subprocess_launcher.dart b/tool/subprocess_launcher.dart
index 31c81c2ef5..9c9ac5d64f 100644
--- a/tool/subprocess_launcher.dart
+++ b/tool/subprocess_launcher.dart
@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:path/path.dart' as p;
 
 /// Keeps track of coverage data automatically for any processes run by this
@@ -43,7 +44,8 @@ class CoverageSubprocessLauncher extends SubprocessLauncher {
 
   /// Call once all coverage runs have been generated by calling runStreamed
   /// on all [CoverageSubprocessLaunchers].
-  static Future<void> generateCoverageToFile(File outputFile) async {
+  static Future<void> generateCoverageToFile(
+      File outputFile, ResourceProvider resourceProvider) async {
     if (!coverageEnabled) return Future.value(null);
     var currentCoverageResults = coverageResults;
     coverageResults = [];