Remove direct file system calls from HotAvalonia

Use `IFileSystem` instead.
This way we can finally implement #10.

src/HotAvalonia/Assets/AssetInfo.cs

@@ -1,6 +1,4 @@
 using System.Reflection;
-using HotAvalonia.Helpers;
-using Paths = System.IO.Path;
 
 namespace HotAvalonia.Assets;
 
@@ -43,27 +41,4 @@ public AssetInfo(Uri uri, Assembly assembly, Uri project, string path)
         Project = project;
         Path = path;
     }
-
-    /// <summary>
-    /// Initializes a new instance of the <see cref="AssetInfo"/> class.
-    /// </summary>
-    /// <param name="uri">The URI of the asset.</param>
-    /// <param name="assembly">The assembly associated with the asset.</param>
-    /// <param name="project">The path of the project root containing the asset.</param>
-    /// <param name="path">
-    /// The path of the asset. If <c>null</c>, the path is resolved automatically
-    /// from the <paramref name="project"/> and <paramref name="uri"/>.
-    /// </param>
-    public AssetInfo(Uri uri, Assembly assembly, string project, string? path = null)
-    {
-        project = Paths.GetFullPath(project);
-        char projectEnd = project.Length > 0 ? project[project.Length - 1] : Paths.DirectorySeparatorChar;
-        if (projectEnd != Paths.DirectorySeparatorChar && projectEnd != Paths.AltDirectorySeparatorChar)
-            project += Paths.DirectorySeparatorChar;
-
-        Uri = uri;
-        Assembly = assembly;
-        Project = new(project);
-        Path = path ?? UriHelper.ResolvePathFromUri(project, uri);
-    }
 }

src/HotAvalonia/Assets/DynamicAsset.cs

@@ -77,11 +77,12 @@ static DynamicAsset()
     /// Initializes a new instance of the <see cref="DynamicAsset{TAsset}"/> class using a URI.
     /// </summary>
     /// <param name="uri">The URI of the asset.</param>
-    private DynamicAsset(Uri uri)
+    /// <param name="fileSystem">The file system where the asset can be found.</param>
+    private DynamicAsset(Uri uri, IFileSystem fileSystem)
     {
         _uri = uri;
         _asset = s_create(this, null);
-        _fileObserver = new(uri.LocalPath, Refresh);
+        _fileObserver = new(fileSystem, uri.LocalPath, Refresh);
     }
 
     /// <summary>
@@ -90,11 +91,12 @@ private DynamicAsset(Uri uri)
     /// <param name="stream">The stream containing the asset data.</param>
     /// <param name="uri">The URI of the asset.</param>
     /// <param name="fileName">The file name of the asset.</param>
-    private DynamicAsset(Stream stream, Uri uri, string fileName)
+    /// <param name="fileSystem">The file system where the asset can be found.</param>
+    private DynamicAsset(Stream stream, Uri uri, string fileName, IFileSystem fileSystem)
     {
         _uri = uri;
         _asset = s_create(this, stream);
-        _fileObserver = new(fileName, Refresh);
+        _fileObserver = new(fileSystem, fileName, Refresh);
     }
 
     /// <summary>
@@ -122,7 +124,7 @@ public static TAsset Create(Uri uri, Uri? baseUri, AvaloniaProjectLocator projec
             uri = new(baseUri, uri);
 
         if (uri.IsAbsoluteUri && uri.IsFile)
-            return new DynamicAsset<TAsset>(uri).Asset;
+            return new DynamicAsset<TAsset>(uri, projectLocator.FileSystem).Asset;
 
         (Stream stream, Assembly assembly) = AssetLoader.OpenAndGetAssembly(uri);
         if (!uri.IsAbsoluteUri || uri.Scheme != UriHelper.AvaloniaResourceScheme)
@@ -131,8 +133,8 @@ public static TAsset Create(Uri uri, Uri? baseUri, AvaloniaProjectLocator projec
         if (!projectLocator.TryGetDirectoryName(assembly, out string? rootPath))
             return s_fromStream(stream);
 
-        string fileName = UriHelper.ResolvePathFromUri(rootPath, uri);
-        return new DynamicAsset<TAsset>(stream, uri, fileName).Asset;
+        string fileName = projectLocator.FileSystem.ResolvePathFromUri(rootPath, uri);
+        return new DynamicAsset<TAsset>(stream, uri, fileName, projectLocator.FileSystem).Asset;
     }
 
     /// <summary>

src/HotAvalonia/Assets/DynamicAssetLoader.cs

@@ -30,7 +30,7 @@ internal class DynamicAssetLoader
     /// <summary>
     /// The file system accessor.
     /// </summary>
-    protected readonly CachingFileSystemAccessor _fileSystem;
+    protected readonly IFileSystem _fileSystem;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="DynamicAssetLoader"/> class.
@@ -45,7 +45,7 @@ protected DynamicAssetLoader(IAssetLoader fallbackAssetLoader, AvaloniaProjectLo
     {
         _assetLoader = fallbackAssetLoader ?? throw new ArgumentNullException(nameof(fallbackAssetLoader));
         _projectLocator = projectLocator ?? throw new ArgumentNullException(nameof(projectLocator));
-        _fileSystem = new();
+        _fileSystem = new CachingFileSystem(projectLocator.FileSystem);
     }
 
     /// <inheritdoc cref="Create(IAssetLoader, AvaloniaProjectLocator)"/>
@@ -76,7 +76,7 @@ public bool Exists(Uri uri, Uri? baseUri = null)
             return true;
 
         if (TryGetAssetInfo(uri, baseUri, out AssetInfo? asset))
-            return File.Exists(asset.Path);
+            return _fileSystem.FileExists(asset.Path);
 
         return false;
     }
@@ -86,13 +86,13 @@ public IEnumerable<Uri> GetAssets(Uri uri, Uri? baseUri)
     {
         IEnumerable<Uri> assets = _assetLoader.GetAssets(uri, baseUri);
 
-        if (TryGetAssetInfo(uri, baseUri, out AssetInfo? asset) && Directory.Exists(asset.Path))
+        if (TryGetAssetInfo(uri, baseUri, out AssetInfo? asset) && _fileSystem.DirectoryExists(asset.Path))
         {
             Uri assemblyUri = new UriBuilder(asset.Uri.Scheme, asset.Uri.Host).Uri;
             Uri projectUri = asset.Project;
-            IEnumerable<Uri> fileAssets = Directory
+            IEnumerable<Uri> fileAssets = _fileSystem
                 .EnumerateFiles(asset.Path, "*", SearchOption.AllDirectories)
-                .Select(x => projectUri.MakeRelativeUri(new(Path.GetFullPath(x))))
+                .Select(x => projectUri.MakeRelativeUri(new(x)))
                 .Select(x => new Uri(assemblyUri, x));
 
             assets = assets.Concat(fileAssets).Distinct();
@@ -108,10 +108,10 @@ public Stream Open(Uri uri, Uri? baseUri = null)
     /// <inheritdoc cref="IAssetLoader.OpenAndGetAssembly(Uri, Uri?)"/>
     public (Stream stream, Assembly assembly) OpenAndGetAssembly(Uri uri, Uri? baseUri = null)
     {
-        if (!TryGetAssetInfo(uri, baseUri, out AssetInfo? asset) || !_fileSystem.Exists(asset.Path))
+        if (!TryGetAssetInfo(uri, baseUri, out AssetInfo? asset) || !_fileSystem.FileExists(asset.Path))
             return _assetLoader.OpenAndGetAssembly(uri, baseUri);
 
-        return (_fileSystem.Open(asset.Path), asset.Assembly);
+        return (_fileSystem.OpenRead(asset.Path), asset.Assembly);
     }
 
     /// <summary>
@@ -144,9 +144,26 @@ private bool TryGetAssetInfo(Uri uri, Uri? baseUri, [NotNullWhen(true)] out Asse
         if (!_projectLocator.TryGetDirectoryName(assembly, out string? rootPath))
             return false;
 
-        assetInfo = new(absoluteUri, assembly, rootPath);
+        assetInfo = ResolveAssetInfo(absoluteUri, assembly, rootPath);
         return true;
     }
+
+    /// <summary>
+    /// Resolves an asset from the given URI.
+    /// </summary>
+    /// <param name="uri">The URI of the asset.</param>
+    /// <param name="assembly">The assembly associated with the asset.</param>
+    /// <param name="project">The path of the project root containing the asset.</param>
+    /// <returns>A resolved <see cref="AssetInfo"/> instance.</returns>
+    private AssetInfo ResolveAssetInfo(Uri uri, Assembly assembly, string project)
+    {
+        project = _fileSystem.GetFullPath(project);
+        char projectEnd = project.Length > 0 ? project[project.Length - 1] : _fileSystem.DirectorySeparatorChar;
+        if (projectEnd != _fileSystem.DirectorySeparatorChar && projectEnd != _fileSystem.AltDirectorySeparatorChar)
+            project += _fileSystem.DirectorySeparatorChar;
+
+        return new(uri, assembly, new(project), _fileSystem.ResolvePathFromUri(project, uri));
+    }
 }
 
 /// <summary>

src/HotAvalonia/AvaloniaControlManager.cs

@@ -21,11 +21,6 @@ public sealed class AvaloniaControlManager : IDisposable
     /// </summary>
     private readonly WeakSet<object> _controls;
 
-    /// <summary>
-    /// The name of the XAML file associated with the control.
-    /// </summary>
-    private string _fileName;
-
     /// <summary>
     /// The dynamically compiled populate method associated with the control.
     /// </summary>
@@ -41,14 +36,9 @@ public sealed class AvaloniaControlManager : IDisposable
     /// Initializes a new instance of the <see cref="AvaloniaControlManager"/> class.
     /// </summary>
     /// <param name="controlInfo">The Avalonia control information.</param>
-    /// <param name="fileName">The name of the XAML file.</param>
-    public AvaloniaControlManager(AvaloniaControlInfo controlInfo, string fileName)
+    public AvaloniaControlManager(AvaloniaControlInfo controlInfo)
     {
-        _ = controlInfo ?? throw new ArgumentNullException(nameof(controlInfo));
-        _ = fileName ?? throw new ArgumentNullException(nameof(fileName));
-
-        _controlInfo = controlInfo;
-        _fileName = fileName;
+        _controlInfo = controlInfo ?? throw new ArgumentNullException(nameof(controlInfo));
         _controls = new();
 
         if (!TryInjectPopulateCallback(controlInfo, OnPopulate, out _populateInjection))
@@ -60,38 +50,20 @@ public AvaloniaControlManager(AvaloniaControlInfo controlInfo, string fileName)
     /// </summary>
     public AvaloniaControlInfo Control => _controlInfo;
 
-    /// <summary>
-    /// The name of the XAML file associated with the control.
-    /// </summary>
-    public string FileName
-    {
-        get => _fileName;
-        set => _fileName = value ?? throw new ArgumentNullException(nameof(value));
-    }
-
     /// <inheritdoc/>
     public void Dispose()
         => _populateInjection?.Dispose();
 
     /// <summary>
     /// Reloads the controls associated with this manager asynchronously.
     /// </summary>
-    /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
-    public async Task ReloadAsync(CancellationToken cancellationToken = default)
-    {
-        if (!File.Exists(_fileName))
-            return;
-
-        string xaml = await FileHelper.ReadAllTextAsync(_fileName, cancellationToken: cancellationToken).ConfigureAwait(true);
-        await Dispatcher.UIThread.InvokeAsync(() => ReloadAsync(xaml, cancellationToken), DispatcherPriority.Render);
-    }
-
-    /// <summary>
-    /// Reloads the controls associated with this manager on the UI thread.
-    /// </summary>
     /// <param name="xaml">The XAML markup to reload the control from.</param>
     /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
-    private async Task ReloadAsync(string xaml, CancellationToken cancellationToken)
+    public Task ReloadAsync(string xaml, CancellationToken cancellationToken = default)
+        => Dispatcher.UIThread.InvokeAsync(() => UnsafeReloadAsync(xaml, cancellationToken), DispatcherPriority.Render);
+
+    /// <inheritdoc cref="ReloadAsync(string, CancellationToken)"/>
+    private async Task UnsafeReloadAsync(string xaml, CancellationToken cancellationToken)
     {
         cancellationToken.ThrowIfCancellationRequested();