Properly bind "this" for beforeEach/it/afterEach in mocha integration.

Fixes issue 7105.

javascript/node/selenium-webdriver/CHANGES.md

@@ -1,3 +1,7 @@
+## v2.41.0-dev
+
+* FIXED: 7105: beforeEach/it/afterEach properly bind `this` for Mocha tests.
+
 ## v2.40.0
 
 * API documentation is now included in the docs directory.

javascript/node/selenium-webdriver/test/testing/index_test.js

@@ -0,0 +1,41 @@
+// Copyright 2013 Selenium committers
+// Copyright 2013 Software Freedom Conservancy
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+//     You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+'use strict';
+
+var assert = require('assert');
+
+var test = require('../../testing');
+
+describe('Mocha Integration', function() {
+
+  describe('beforeEach properly binds "this"', function() {
+    beforeEach(function() { this.x = 1; });
+    test.beforeEach(function() { this.x = 2; });
+    it('', function() { assert.equal(this.x, 2); });
+  });
+
+  describe('afterEach properly binds "this"', function() {
+    it('', function() { this.x = 1; });
+    test.afterEach(function() { this.x = 2; });
+    afterEach(function() { assert.equal(this.x, 2); });
+  });
+
+  describe('it properly binds "this"', function() {
+    beforeEach(function() { this.x = 1; });
+    test.it('', function() { this.x = 2; });
+    afterEach(function() { assert.equal(this.x, 2); });
+  });
+});

javascript/node/selenium-webdriver/testing/index.js

@@ -120,7 +120,13 @@ function wrapped(globalFn) {
   function asyncTestFn(fn) {
     return function(done) {
       this.timeout(0);
-      flow.execute(fn).then(seal(done), done);
+      var timeout = this.timeout;
+      this.timeout = undefined;  // Do not let tests change the timeout.
+      try {
+        flow.execute(fn.bind(this)).then(seal(done), done);
+      } finally {
+        this.timeout = timeout;
+      }
     };
   }
 }