Fixes/run mocha on child process workers

lib/runner/cli/cli.js

@@ -24,7 +24,7 @@ class CliRunner {
   static get CONFIG_FILE_TS() {
     return './nightwatch.conf.ts';
   }
- 
+
   static createDefaultConfig(destFileName) {
     // eslint-disable-next-line no-console
     console.log(Logger.colors.cyan('No config file found in the current working directory, creating nightwatch.conf.js in the current folder...'));
@@ -149,7 +149,7 @@ class CliRunner {
       }
     }
   }
-  
+
   setMobileOptions(argv) {
     const {desiredCapabilities, selenium = {}} = this.test_settings;
 
@@ -194,7 +194,7 @@ class CliRunner {
 
     if (!this.baseSettings) {
       return this;
-    }  
+    }
 
     this.availableTestEnvs = Object.keys(this.baseSettings.test_settings).filter(key => {
       return Utils.isObject(this.baseSettings.test_settings[key]);
@@ -262,7 +262,7 @@ class CliRunner {
       test_workers_enabled: this.test_settings.testWorkersEnabled,
       use_xpath: this.test_settings.use_xpath,
       is_bstack: this.test_settings.desiredCapabilities['bstack:options'] !== undefined,
-      test_runner: this.test_settings.test_runner ? this.test_settings.test_runner.type : null 
+      test_runner: this.test_settings.test_runner ? this.test_settings.test_runner.type : null
     });
   }
 
@@ -297,7 +297,7 @@ class CliRunner {
     if (usingTS) {
       return path.resolve(CliRunner.CONFIG_FILE_TS);
     }
- 
+
     return path.resolve(CliRunner.CONFIG_FILE_JS);
   }
 
@@ -402,13 +402,13 @@ class CliRunner {
     for (const env of this.testEnvArray) {
       const {webdriver = {}} = this.testEnvSettings[env];
       const desiredCapabilities = this.testEnvSettings[env].capabilities || this.testEnvSettings[env].desiredCapabilities;
-      
+
       if (isMobile(desiredCapabilities)) {
-        
+
         if  (Concurrency.isWorker()) {
           Logger.info('Disabling parallelism while running tests on mobile platform');
         }
-        
+
         return false;
       }
 
@@ -432,6 +432,11 @@ class CliRunner {
   }
 
   setupConcurrency() {
+
+    if (this.testRunner?.type === Runner.MOCHA_RUNNER) {
+      this.test_settings.use_child_process = true;
+    }
+
     this.concurrency = new Concurrency(this.test_settings, this.argv, this.isTestWorkersEnabled());
 
     return this;
@@ -492,7 +497,7 @@ class CliRunner {
     return this.runGlobalHook('before', [this.test_settings])
       .then(_ => {
         return this.runGlobalHook('beforeChildProcess', [this.test_settings], true);
-      }) 
+      })
       .then(_ => {
         return this.getTestsFiles();
       })
@@ -628,7 +633,7 @@ class CliRunner {
         }
 
         analyticsCollector.__flush();
- 
+
         return errorOrFailed;
       });
   }

test/src/cli/testCliRunnerMocha.js

@@ -26,6 +26,7 @@ describe('test CLI Runner Mocha', function() {
       resolve: function(a) {
         return a;
       },
+      extname: path.extname,
       join: path.join
     });
 
@@ -89,6 +90,49 @@ describe('test CLI Runner Mocha', function() {
     });
   });
 
+  it('testRunWithMocha - parallelism', function() {
+
+    const ChildProcess = common.require('runner/concurrency/child-process.js');
+    let childProcessCreated = false;
+    class ChildProcessMock extends ChildProcess {
+      run(colors, type) {
+        childProcessCreated = true;
+        assert.strictEqual(colors.length, 4);
+        assert.strictEqual(type, 'workers');
+        assert.deepStrictEqual(Object.keys(this._events), ['message']);
+
+        return Promise.resolve(0);
+      }
+    }
+
+    mockery.registerMock('./child-process.js', ChildProcessMock);
+
+    mockery.registerMock('./withmocha.json', {
+      src_folders: ['tests'],
+      output_folder: false,
+      use_child_process: false,
+      test_settings: {
+        'default': {
+          silent: true
+        }
+      },
+      test_runner: 'mocha'
+    });
+
+
+    const CliRunner = common.require('runner/cli/cli.js');
+    const runner = new CliRunner({
+      config: './withmocha.json',
+      env: 'default',
+      reporter: 'junit',
+      parallel: true
+    }).setup();
+
+    return runner.runTests().then(function() {
+      assert.ok(childProcessCreated, 'mocha runner with parallel threads should use child process');
+    });
+  });
+
   it('testRunWithMochaPerEnvironment', function() {
     const testFiles = [];
     const defaultOptions = {timeout: 20000, reporterOptions: {}};