Add element property (nightwatchjs#2189)

Added W3C Webdriver related element property commands - "getElementProperty" and "elementIdProperty" protocol action.

lib/api/element-commands/getElementProperty.js

@@ -0,0 +1,35 @@
+const BaseElementCommand = require('./_baseElementCommand.js');
+
+/**
+ * Retrieve the value of a property for a given DOM element. Uses `elementIdProperty` protocol command.
+ *
+ * @example
+ * this.demoTest = function (browser) {
+ *   browser.getElementProperty("#main ul li a.first", "href", function(result) {
+ *     this.assert.equal(typeof result, "object");
+ *     this.assert.equal(result.status, 0);
+ *     this.assert.equal(result.value, 'https://nightwatchjs.org/');
+ *   });
+ * };
+ *
+ *
+ * @method getElementProperty
+ * @syntax .getElementProperty(selector, property, callback)
+ * @param {string} selector The CSS/Xpath selector used to locate the element.
+ * @param {string} property The property to inspect.
+ * @param {function} callback Callback function which is called with the result value.
+ * @see elementIdProperty
+ * @returns {*} The value of the property
+ * @api protocol.elementstate
+ */
+class GetElementProperty extends BaseElementCommand {
+  get extraArgsCount() {
+    return 1;
+  }
+
+  get elementProtocolAction() {
+    return 'getElementProperty';
+  }
+}
+
+module.exports = GetElementProperty;

lib/api/protocol.js

@@ -1145,6 +1145,24 @@ module.exports = class ProtocolActions {
         return this.TransportActions.getElementCSSValue(webElementId, cssPropertyName, callback);
       },
 
+      /**
+       * Retrieve the computed value of the given property of the given element.
+       *
+       * The property to query should be specified using the CSS property name, not the JavaScript property name (e.g. background-color instead of backgroundColor).
+       *
+       * @link /#get-element-property
+       * @param {string} webElementId The [Web Element ID](https://www.w3.org/TR/webdriver1/#dfn-web-elements) of the element to route the command to.
+       * @param {string} propertyName
+       * @param {function} callback Callback function which is called with the result value.
+       * @api protocol.elementinternal
+       * @internal
+       */
+      elementIdProperty(webElementId, propertyName, callback) {
+        ProtocolActions.validateElementId(webElementId, 'elementIdProperty');
+
+        return this.TransportActions.getElementProperty(webElementId, propertyName, callback);
+      },
+
       /**
        * Scrolls into view a submittable element excluding buttons or editable element, and then attempts to clear its value, reset the checked state, or text content.
        *

lib/transport/jsonwire/actions.js

@@ -252,6 +252,10 @@ module.exports = {
       return `/element/${id}/css/${cssPropertyName}`;
     },
 
+    getElementProperty(id, propertyName) {
+      return `/element/${id}/property/${propertyName}`;
+    },
+
     getElementTagName(id) {
       return `/element/${id}/name`;
     },

test/lib/nocks.js

@@ -137,6 +137,24 @@ module.exports = {
     return this;
   },
 
+  property(value, times) {
+    var mock = nock('http://localhost:10195')
+      .get('/wd/hub/session/1352110219202/element/0/property/display');
+
+    if (times) {
+      mock.times(times);
+    }
+
+    mock.reply(200, {
+      status: 0,
+      sessionId: '1352110219202',
+      value: value,
+      state: 'success'
+    });
+
+    return this;
+  },
+
   enabled(times) {
     var mock = nock('http://localhost:10195')
       .get('/wd/hub/session/1352110219202/element/0/enabled');

test/src/api/commands/testGetElementProperty.js

@@ -0,0 +1,32 @@
+const assert = require('assert');
+const MockServer  = require('../../../lib/mockserver.js');
+const CommandGlobals = require('../../../lib/globals/commands.js');
+
+describe('getElementProperty', function() {
+  before(function(done) {
+    CommandGlobals.beforeEach.call(this, done);
+  });
+
+  after(function(done) {
+    CommandGlobals.afterEach.call(this, done);
+  });
+
+  it('client.getElementProperty()', function(done) {
+    MockServer.addMock({
+      url : '/wd/hub/session/1352110219202/element/0/property/display',
+      method:'GET',
+      response : JSON.stringify({
+        sessionId: '1352110219202',
+        status:0,
+        value : 'block'
+      })
+    });
+
+    this.client.api.getElementProperty('#weblogin', 'display', function callback(result) {
+      assert.strictEqual(result.value, 'block');
+    });
+
+    this.client.start(done);
+  });
+
+});

test/src/api/protocol/testElementCommands.js

@@ -243,6 +243,28 @@ describe('element actions', function () {
     }).then(result => assert.strictEqual(result, true));
   });
 
+  it('testElementIdProperty', function () {
+    return Globals.protocolTest.call(this, {
+      assertion: function (opts) {
+        assert.equal(opts.method, 'GET');
+        assert.equal(opts.path, '/session/1352110219202/element/TEST_ELEMENT/property/test_property');
+      },
+      commandName: 'elementIdProperty',
+      args: ['TEST_ELEMENT', 'test_property']
+    });
+  });
+
+  it('testElementIdProperty invalid element ID', function () {
+    return Globals.protocolTest.call(this, {
+      commandName: 'elementIdProperty',
+      args: [false, 'test_property']
+    }).catch(err => {
+      assert.equal(err.message, 'First argument passed to .elementIdProperty() should be a web element ID string. Received boolean.');
+
+      return true;
+    }).then(result => assert.strictEqual(result, true));
+  });
+
   it('testElementIdDisplayed', function () {
     return Globals.protocolTest.call(this, {
       assertion: function (opts) {