feat: Added config parsing utility functions aimed at global options, more to come (#744)

Author: shubheksha

package.json

@@ -49,6 +49,7 @@
     "babel-polyfill": "6.20.0",
     "babel-runtime": "6.20.0",
     "bunyan": "1.8.5",
+    "camelcase": "4.0.0",
     "debounce": "1.0.0",
     "es6-error": "4.0.1",
     "es6-promisify": "5.0.0",
@@ -63,6 +64,8 @@
     "node-notifier": "5.0.2",
     "parse-json": "2.2.0",
     "regenerator-runtime": "0.10.1",
+    "require-uncached": "1.0.3",
+    "stream-to-promise": "2.2.0",
     "sign-addon": "0.2.1",
     "source-map-support": "0.4.11",
     "tmp": "0.0.30",

src/config.js

@@ -0,0 +1,63 @@
+/* @flow */
+import path from 'path';
+
+import requireUncached from 'require-uncached';
+
+import {createLogger} from './util/logger';
+import {UsageError} from './errors';
+
+const log = createLogger(__filename);
+
+type ApplyConfigToArgvParams = {|
+  argv: Object,
+  configObject: Object,
+  defaultValues: Object,
+|};
+
+export function applyConfigToArgv({
+  argv,
+  configObject,
+  defaultValues = {},
+}: ApplyConfigToArgvParams): Object {
+  const newArgv = {...argv};
+  for (const option in configObject) {
+    // we assume the value was set on the CLI if the default value is
+    // not the same as that on the argv object as there is a very rare chance
+    // this happening
+    const wasValueSetOnCLI = typeof(argv[option]) !== 'undefined' &&
+      (argv[option] !== defaultValues[option]);
+    if (wasValueSetOnCLI) {
+      log.debug(`Favoring CLI: ${option}=${argv[option]} over ` +
+        `configuration: ${option}=${configObject[option]}`);
+      continue;
+    }
+    if (!argv.hasOwnProperty(option)) {
+      log.debug(`Ignoring configuration: ${option}=${configObject[option]} ` +
+        'because this is an unknown option');
+      continue;
+    }
+    newArgv[option] = configObject[option];
+  }
+  return newArgv;
+}
+
+export function loadJSConfigFile(filePath: string): Object {
+  const resolvedFilePath = path.resolve(filePath);
+  log.debug(
+    `Loading JS config file: "${filePath}" ` +
+    `(resolved to "${resolvedFilePath}")`);
+  let configObject;
+  try {
+    configObject = requireUncached(resolvedFilePath);
+  } catch (error) {
+    log.debug('Handling error:', error);
+    throw new UsageError(
+      `Cannot read config file: ${resolvedFilePath}\n` +
+      `Error: ${error.message}`);
+  }
+  if (Object.keys(configObject).length === 0) {
+    log.debug(`Config file ${resolvedFilePath} did not define any options. ` +
+      'Did you set module.exports = {...}?');
+  }
+  return configObject;
+}

src/program.js

@@ -4,6 +4,7 @@ import {readFileSync} from 'fs';
 
 import git from 'git-rev-sync';
 import yargs from 'yargs';
+import camelCase from 'camelcase';
 
 import defaultCommands from './cmd';
 import {UsageError} from './errors';
@@ -36,6 +37,7 @@ export class Program {
   yargs: any;
   commands: { [key: string]: Function };
   shouldExitProgram: boolean;
+  defaultValues: Object;
 
   constructor(
     argv: ?Array<string>,
@@ -90,7 +92,15 @@ export class Program {
     // This is a convenience for setting global options.
     // An option is only global (i.e. available to all sub commands)
     // with the `global` flag so this makes sure every option has it.
+    this.defaultValues = {};
     Object.keys(options).forEach((key) => {
+      const camelCasedKey = camelCase(key);
+      if (options[key].type === 'boolean') {
+        this.defaultValues[camelCasedKey] = false;
+      }
+      if (typeof(options[key].default) !== 'undefined') {
+        this.defaultValues[camelCasedKey] = options[key].default;
+      }
       options[key].global = true;
       if (options[key].demand === undefined) {
         // By default, all options should be "demanded" otherwise