feat(mocha 6): support all config formats (#1511)

Add support for all mocha's configuration formats:
* Arguments specified on command-line
* Configuration file (.mocharc.js, .mocharc.yml, etc.)
    1. .mocharc.js
    2. .mocharc.yaml
    3. .mocharc.yml
    4. .mocharc.jsonc
    5. .mocharc.json
* mocha property of package.json
* mocha.opts

This works by using mocha 6's [`loadOptions`](https://mochajs.org/api/module-lib_cli_options.html#.loadOptions) function if it is available.
If not (mocha < 6), use old parsing logic.

See https://mochajs.org/#configuring-mocha-nodejs

packages/mocha-framework/package.json

@@ -41,7 +41,7 @@
   },
   "peerDependencies": {
     "@stryker-mutator/core": "^1.0.0",
-    "mocha": ">= 2.3.3 < 6"
+    "mocha": ">= 2.3.3 < 7"
   },
   "dependencies": {
     "@stryker-mutator/api": "^1.2.0"

packages/mocha-runner/README.md

@@ -36,7 +36,9 @@ module.exports = function (config) {
         mochaOptions: {
             // Optional mocha options
             files: [ 'test/**/*.js' ]
-            opts: 'path/to/mocha.opts',
+            config: 'path/to/mocha/config/.mocharc.json',
+            package: 'path/to/custom/package/package.json',
+            opts: 'path/to/custom/mocha.opts',
             ui: 'bdd',
             timeout: 3000,
             require: [ /*'babel-register' */],
@@ -47,6 +49,11 @@ module.exports = function (config) {
 }
 ```
 
+When using Mocha version 6, @stryker-mutator/mocha-runner will use [mocha's internal file loading mechanism](https://mochajs.org/api/module-lib_cli_options.html#.loadOptions) to load your mocha configuration.
+So feel free to _leave out the mochaOptions entirely_ if you're using one of the [default file locations](https://mochajs.org/#configuring-mocha-nodejs).
+
+Alternatively, use `['no-config']: true`, `['no-package']: true` or `['no-opts']: true` to ignore the default mocha config, default mocha package.json and default mocha opts locations respectively. 
+
 ### `mochaOptions.files` [`string` or `string[]`]
 
 Default: `'test/**/*.js'`
@@ -55,6 +62,23 @@ Choose which files to include. This is comparable to [mocha's test directory](ht
 
 If you want to load all files recursively: use a globbing expression (`'test/**/*.js'`). If you want to decide on the order of files, use multiple globbing expressions. For example: use `['test/helpers/**/*.js', 'test/unit/**/*.js']` if you want to make sure your helpers are loaded before your unit tests.
 
+### `mochaOptions.config` [`string` | `undefined`]
+
+Default: `undefined`
+
+Explicit path to the [mocha config file](https://mochajs.org/#-config-path)
+
+*New since Mocha 6*
+
+### `mochaOptions.package` [`string` | `undefined`]
+
+Default: `undefined`
+
+Specify an explicit path to a package.json file (ostensibly containing configuration in a mocha property).
+See https://mochajs.org/#-package-path.
+
+*New since Mocha 6*
+
 ### `mochaOptions.opts` [`string` | false]
 
 Default: `'test/mocha.opts'`

packages/mocha-runner/package.json

@@ -46,6 +46,6 @@
   },
   "peerDependencies": {
     "@stryker-mutator/core": "^1.0.0",
-    "mocha": ">= 2.3.3 < 6"
+    "mocha": ">= 2.3.3 < 7"
   }
 }

packages/mocha-runner/src/LibWrapper.ts

@@ -1,11 +1,25 @@
 import * as Mocha from 'mocha';
 import * as multimatch from 'multimatch';
 
+let loadOptions: undefined | ((argv?: string[] | string) => MochaOptions | undefined);
+
+try {
+  /*
+  * If read, object containing parsed arguments
+  * @since 6.0.0'
+  * @see https://mochajs.org/api/module-lib_cli_options.html#.loadOptions
+  */
+  loadOptions = require('mocha/lib/cli/options').loadOptions;
+} catch {
+  // Mocha < 6 doesn't support `loadOptions`
+}
+
 /**
  * Wraps Mocha class and require for testability
  */
 export default class LibWrapper {
   public static Mocha = Mocha;
   public static require = require;
   public static multimatch = multimatch;
+  public static loadOptions = loadOptions;
 }

packages/mocha-runner/src/MochaConfigEditor.ts

@@ -1,5 +1,5 @@
 import { ConfigEditor, Config } from '@stryker-mutator/api/config';
-import { mochaOptionsKey } from './MochaRunnerOptions';
+import { mochaOptionsKey } from './utils';
 import MochaOptionsLoader from './MochaOptionsLoader';
 import { tokens } from '@stryker-mutator/api/plugin';
 

packages/mocha-runner/src/MochaOptionsLoader.ts

@@ -1,9 +1,10 @@
 import * as path from 'path';
 import * as fs from 'fs';
 import { StrykerOptions } from '@stryker-mutator/api/core';
-import MochaRunnerOptions, { mochaOptionsKey } from './MochaRunnerOptions';
 import { tokens, commonTokens } from '@stryker-mutator/api/plugin';
 import { Logger } from '@stryker-mutator/api/logging';
+import { serializeArguments, filterConfig, mochaOptionsKey } from './utils';
+import LibWrapper from './LibWrapper';
 
 export default class MochaOptionsLoader {
 
@@ -12,12 +13,27 @@ export default class MochaOptionsLoader {
   public static inject = tokens(commonTokens.logger);
   constructor(private readonly log: Logger) { }
 
-  public load(config: StrykerOptions): MochaRunnerOptions {
-    const mochaOptions = Object.assign({}, config[mochaOptionsKey]) as MochaRunnerOptions;
-    return Object.assign(this.loadMochaOptsFile(mochaOptions.opts), mochaOptions);
+  public load(strykerOptions: StrykerOptions): MochaOptions {
+    const mochaOptions = { ...strykerOptions[mochaOptionsKey] } as MochaOptions;
+    return { ... this.loadMochaOptions(mochaOptions), ...mochaOptions };
   }
 
-  private loadMochaOptsFile(opts: false | string | undefined): MochaRunnerOptions {
+  private loadMochaOptions(overrides: MochaOptions) {
+    if (LibWrapper.loadOptions) {
+      this.log.debug('Mocha > 6 detected. Using mocha\'s `%s` to load mocha options', LibWrapper.loadOptions.name);
+      const args = serializeArguments(overrides);
+      const rawConfig = LibWrapper.loadOptions(args) || {};
+      if (this.log.isTraceEnabled()) {
+        this.log.trace(`Mocha: ${LibWrapper.loadOptions.name}([${args.map(arg => `'${arg}'`).join(',')}]) => ${JSON.stringify(rawConfig)}`);
+      }
+      return filterConfig(rawConfig);
+    } else {
+      this.log.debug('Mocha < 6 detected. Using custom logic to parse mocha options');
+      return this.loadMochaOptsFile(overrides.opts);
+    }
+  }
+
+  private loadMochaOptsFile(opts: false | string | undefined): MochaOptions {
     switch (typeof opts) {
       case 'boolean':
         this.log.debug('Not reading additional mochaOpts from a file');
@@ -46,9 +62,9 @@ export default class MochaOptionsLoader {
     return this.parseOptsFile(fs.readFileSync(optsFileName, 'utf8'));
   }
 
-  private parseOptsFile(optsFileContent: string): MochaRunnerOptions {
+  private parseOptsFile(optsFileContent: string): MochaOptions {
     const options = optsFileContent.split('\n').map(val => val.trim());
-    const mochaRunnerOptions: MochaRunnerOptions = Object.create(null);
+    const mochaRunnerOptions: MochaOptions = Object.create(null);
     options.forEach(option => {
       const args = option.split(' ').filter(Boolean);
       if (args[0]) {

packages/mocha-runner/src/MochaTestRunner.ts

@@ -3,8 +3,7 @@ import * as path from 'path';
 import { TestRunner, RunResult, RunStatus } from '@stryker-mutator/api/test_runner';
 import LibWrapper from './LibWrapper';
 import { StrykerMochaReporter } from './StrykerMochaReporter';
-import MochaRunnerOptions, { mochaOptionsKey } from './MochaRunnerOptions';
-import { evalGlobal } from './utils';
+import { mochaOptionsKey, evalGlobal } from './utils';
 import { StrykerOptions } from '@stryker-mutator/api/core';
 import { tokens, commonTokens } from '@stryker-mutator/api/plugin';
 
@@ -13,7 +12,7 @@ const DEFAULT_TEST_PATTERN = 'test/**/*.js';
 export default class MochaTestRunner implements TestRunner {
 
   private testFileNames: string[];
-  private readonly mochaRunnerOptions: MochaRunnerOptions;
+  private readonly mochaRunnerOptions: MochaOptions;
 
   public static inject = tokens(commonTokens.logger, commonTokens.sandboxFileNames, commonTokens.options);
   constructor(private readonly log: Logger, private readonly allFileNames: ReadonlyArray<string>, options: StrykerOptions) {

packages/mocha-runner/src/utils.ts

@@ -6,3 +6,38 @@ export function evalGlobal(body: string) {
   const fn = new Function('require', body);
   fn(require);
 }
+
+export function serializeArguments(mochaOptions: MochaOptions) {
+  const args: string[] = [];
+  Object.keys(mochaOptions).forEach(key => {
+    args.push(`--${key}`);
+    args.push((mochaOptions as any)[key].toString());
+  });
+  return args;
+}
+
+export const mochaOptionsKey = 'mochaOptions';
+
+const SUPPORTED_MOCHA_OPTIONS = Object.freeze([
+  'extension',
+  'require',
+  'timeout',
+  'async-only',
+  'ui',
+  'grep',
+  'exclude',
+  'file'
+]);
+
+/**
+ * Filter out those config values that are actually useful to run mocha with Stryker
+ * @param rawConfig The raw parsed mocha configuration
+ */
+export function filterConfig(rawConfig: { [key: string]: any }): MochaOptions {
+  return Object.keys(rawConfig).reduce((options, nextValue) => {
+    if (SUPPORTED_MOCHA_OPTIONS.some(o => nextValue === o)) {
+      (options as any)[nextValue] = (rawConfig as any)[nextValue];
+    }
+    return options;
+  }, {} as MochaOptions);
+}

packages/mocha-runner/test/integration/MochaOptionsLoader.it.spec.ts

@@ -0,0 +1,133 @@
+import * as path from 'path';
+import { testInjector } from '@stryker-mutator/test-helpers';
+import MochaOptionsLoader from '../../src/MochaOptionsLoader';
+import { expect } from 'chai';
+import { mochaOptionsKey } from '../../src/utils';
+
+describe(`${MochaOptionsLoader.name} integration`, () => {
+  let sut: MochaOptionsLoader;
+  const cwd = process.cwd();
+
+  beforeEach(() => {
+    sut = createSut();
+  });
+
+  afterEach(() => {
+    process.chdir(cwd);
+  });
+
+  it('should support loading from ".mocharc.js"', () => {
+    const configFile = resolveMochaConfig('.mocharc.js');
+    const actualConfig = actLoad({ config: configFile });
+    expect(actualConfig).deep.eq({
+      config: configFile,
+      extension: ['js'],
+      timeout: 2000,
+      ui: 'bdd'
+    });
+  });
+
+  it('should support loading from ".mocharc.json"', () => {
+    const configFile = resolveMochaConfig('.mocharc.json');
+    const actualConfig = actLoad({ config: configFile });
+    expect(actualConfig).deep.eq({
+      config: configFile,
+      extension: ['json', 'js'],
+      timeout: 2000,
+      ui: 'bdd'
+    });
+  });
+
+  it('should support loading from ".mocharc.jsonc"', () => {
+    const configFile = resolveMochaConfig('.mocharc.jsonc');
+    const actualConfig = actLoad({ config: configFile });
+    expect(actualConfig).deep.eq({
+      config: configFile,
+      extension: ['jsonc', 'js'],
+      timeout: 2000,
+      ui: 'bdd'
+    });
+  });
+
+  it('should support loading from ".mocharc.yml"', () => {
+    const configFile = resolveMochaConfig('.mocharc.yml');
+    const actualConfig = actLoad({ config: configFile });
+    expect(actualConfig).deep.eq({
+      ['async-only']: false,
+      config: configFile,
+      exclude: [
+        '/path/to/some/excluded/file'
+      ],
+      extension: [
+        'yml',
+        'js'
+      ],
+      file: [
+        '/path/to/some/file',
+        '/path/to/some/other/file'
+      ],
+      require: [
+        '@babel/register'
+      ],
+      timeout: 0,
+      ui: 'bdd'
+    });
+  });
+
+  it('should support loading from "package.json"', () => {
+    const pkgFile = resolveMochaConfig('package.json');
+    const actualConfig = actLoad({ package: pkgFile });
+    expect(actualConfig).deep.eq({
+      ['async-only']: true,
+      extension: ['json', 'js'],
+      package: pkgFile,
+      timeout: 20,
+      ui: 'tdd'
+    });
+  });
+
+  it('should respect mocha default file order', () => {
+    process.chdir(resolveMochaConfig('.'));
+    const actualConfig = actLoad({});
+    expect(actualConfig).deep.eq({
+      ['async-only']: true,
+      extension: [
+        'js',
+        'json'
+      ],
+      timeout: 2000,
+      ui: 'bdd'
+    });
+  });
+
+  it('should support `no-config`, `no-opts` and `no-package` keys', () => {
+    process.chdir(resolveMochaConfig('.'));
+    const actualConfig = actLoad({
+      ['no-config']: true,
+      ['no-package']: true,
+      ['no-opts']: true
+    });
+    const expectedOptions = {
+      extension: ['js'],
+      ['no-config']: true,
+      ['no-opts']: true,
+      ['no-package']: true,
+      timeout: 2000,
+      ui: 'bdd'
+    };
+    expect(actualConfig).deep.eq(expectedOptions);
+  });
+
+  function resolveMochaConfig(relativeName: string) {
+    return path.resolve(__dirname, '..', '..', 'testResources', 'mocha-config', relativeName);
+  }
+
+  function actLoad(mochaConfig: { [key: string]: any }): MochaOptions {
+    testInjector.options[mochaOptionsKey] = mochaConfig;
+    return sut.load(testInjector.options);
+  }
+
+  function createSut() {
+    return testInjector.injector.injectClass(MochaOptionsLoader);
+  }
+});

packages/mocha-runner/test/integration/SampleProject.it.spec.ts

@@ -3,7 +3,6 @@ import MochaTestRunner from '../../src/MochaTestRunner';
 import { TestResult, RunResult, TestStatus, RunStatus } from '@stryker-mutator/api/test_runner';
 import * as chaiAsPromised from 'chai-as-promised';
 import * as path from 'path';
-import MochaRunnerOptions from '../../src/MochaRunnerOptions';
 import { testInjector } from '@stryker-mutator/test-helpers';
 import { commonTokens } from '@stryker-mutator/api/plugin';
 chai.use(chaiAsPromised);
@@ -66,7 +65,7 @@ describe('Running a sample project', () => {
         resolve('testResources/sampleProject/MyMath.js'),
         resolve('testResources/sampleProject/MyMathSpec.js'),
       ];
-      const mochaOptions: MochaRunnerOptions = {
+      const mochaOptions: MochaOptions = {
         files
       };
       testInjector.options.mochaOptions = mochaOptions;