added default axe commands to be overriden by the plugin

examples/tests/duckDuckGo.js

@@ -1,4 +1,7 @@
 describe('duckduckgo example', function() {
+
+  this.tags = ['end-to-end'];
+
   it('Search Nightwatch.js and check results', function(browser) {
     browser
       .navigateTo('https://duckduckgo.com')

examples/tests/ecosia.js

@@ -1,10 +1,13 @@
 describe('Ecosia.org Demo', function() {
 
-  before(browser => browser.navigateTo('https://www.ecosia.org/'));
+  before(browser => {
+		browser
+			.navigateTo('https://www.ecosia.org/');
+  });
 
   it('Demo test ecosia.org', function(browser) {
     browser
-      .waitForElementVisible('body')
+			.waitForElementVisible('body')
       .assert.titleContains('Ecosia')
       .assert.visible('input[type=search]')
       .setValue('input[type=search]', 'nightwatch')

lib/api/_loaders/_command-loader.js

@@ -43,7 +43,11 @@ class BaseCommandLoader extends BaseLoader {
       namespace = BaseLoader.unflattenNamespace(this.api, namespace.slice());
     }
 
-    if (this.nightwatchInstance.isApiMethodDefined(this.commandName, namespace)) {
+    if (this.module.allowOverride) {
+      this.nightwatchInstance.overridableCommands.add(this.commandName);
+    }
+
+    if (this.nightwatchInstance.isApiMethodDefined(this.commandName, namespace) && !this.nightwatchInstance.overridableCommands.has(this.commandName)) {
       const err = new TypeError(`Error while loading the API commands: the ${this.type} ${this.namespace || ''}.${this.commandName}() is already defined.`);
       err.displayed = false;
       err.detailedErr = `Source: ${this.fileName}`;

lib/api/client-commands/axeInject.js

@@ -0,0 +1,27 @@
+/**
+ * Injects the [axe-core](https://github.com/dequelabs/axe-core) js library into the current page (using the .executeScript() command).
+ *
+ * @example
+ * describe('accessibility testing', function() {
+ *
+ *   it('accessibility rule subset', function(browser) {
+ *     browser
+ *       .url('https://www.w3.org/WAI/demos/bad/after/home.html')
+ *       .assert.titleEquals('Welcome to CityLights! [Accessible Home Page]')
+ *       .axeInject()
+ *       .axeRun('body', {
+ *         runOnly: ['color-contrast', 'image-alt'],
+ *       });
+ *   });
+ * })
+ *
+ * @method axeInject
+ * @link https://github.com/dequelabs/axe-core
+ * @syntax browser.axeInject()
+ * @api accessibility
+ */
+module.exports = class AxeInjectAbstract {
+  static get allowOverride() {
+    return true;
+  }
+};

lib/api/client-commands/axeRun.js

@@ -0,0 +1,30 @@
+/**
+ * Analyzes the current page against applied axe rules.
+ *
+ * @example
+ * describe('accessibility testing', function() {
+ *
+ *   it('accessibility rule subset', function(browser) {
+ *     browser
+ *       .url('https://www.w3.org/WAI/demos/bad/after/home.html')
+ *       .assert.titleEquals('Welcome to CityLights! [Accessible Home Page]')
+ *       .axeInject()
+ *       .axeRun('body', {
+ *         runOnly: ['color-contrast', 'image-alt'],
+ *       });
+ *   });
+ * })
+ *
+ * @method axeRun
+ * @link https://github.com/dequelabs/axe-core
+ * @syntax browser.axeRun('body')
+ * @param {string} selector The CSS selector used to locate the element.
+ * @param {object} options Object containing rules configuration to use when performing the analysis
+ * @param {function} [callback] Optional callback function which is called with the results
+ * @api accessibility
+ */
+module.exports = class AxeInject {
+  static get allowOverride() {
+    return true;
+  }
+};

lib/core/client.js

@@ -166,6 +166,8 @@ class NightwatchClient extends EventEmitter {
       }
     };
 
+    this.__overridableCommands = new Set();
+
     this.__api = new NightwatchAPI(this.sessionId, this.settings);
 
     this.__api.createElement = (locator, options = {}) => {
@@ -180,6 +182,10 @@ class NightwatchClient extends EventEmitter {
       .setSessionOptions();
   }
 
+  get overridableCommands() {
+    return this.__overridableCommands;
+  }
+
   get api() {
     return this.__api;
   }

test/src/api/commands/client/testAxeCommands.js

@@ -0,0 +1,19 @@
+const assert = require('assert');
+const CommandGlobals = require('../../../../lib/globals/commands.js');
+
+describe('accessibility commands', function () {
+
+  before(function (done) {
+    CommandGlobals.beforeEach.call(this, done);
+  });
+
+  after(function (done) {
+    CommandGlobals.afterEach.call(this, done);
+  });
+
+  it('test axe commands loaded onto the main api', function () {
+    assert.strictEqual(typeof this.client.api.axeInject, 'function');
+    assert.strictEqual(typeof this.client.api.axeRun, 'function');
+  });
+
+});