[Common UI] Implement mct-scroll-* parent

Implement parent directive for mct-scroll-x, mct-scroll-y.
WTD-920.

platform/commonUI/general/src/directives/MCTScroll.js

@@ -0,0 +1,57 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        'use strict';
+
+        /**
+         * Superclass of mct-scroll-x and mct-scroll-y directives. Listens
+         * for scroll events and publishes their results into scope; watches
+         * scope and updates scroll state to match. This varies for x- and y-
+         * directives only by the attribute name chosen to find the expression,
+         * and the property (scrollLeft or scrollTop) managed within the
+         * element.
+         * @constructor
+         * @param $parse Angular's $parse
+         * @param {string} property property to manage within the HTML element
+         * @param {string} attribute attribute to look at for the assignable
+         *        Angular expression
+         */
+        function MCTScroll($parse, property, attribute) {
+            function link(scope, element, attrs) {
+                var expr = attrs[attribute],
+                    parsed = $parse(expr);
+
+                // Set the element's scroll to match the scope's state
+                function updateElement(value) {
+                    element[0][property] = value;
+                }
+
+                // Handle event; assign to scroll state to scope
+                function updateScope() {
+                    parsed.assign(element[0][property]);
+                }
+
+                // Initialize state in scope
+                updateScope();
+
+                // Update element state when value in scope changes
+                scope.$watch(expr, updateElement);
+
+                // Update state in scope when element is scrolled
+                element.on('scroll', updateScope);
+            }
+
+            return {
+                // Restrict to attributes
+                restrict: "A",
+                // Use this link function
+                link: link
+            };
+        }
+
+        return MCTScroll;
+
+    }
+);

platform/commonUI/general/test/directives/MCTScrollSpec.js

@@ -27,7 +27,7 @@ define(
                 mockParsed.assign = jasmine.createSpy('assign');
 
                 mockScope = jasmine.createSpyObj('$scope', ['$watch']);
-                mockElement = [{ scrollLeft: 42 }];
+                mockElement = [{ testProperty: 42 }];
                 mockElement.on = jasmine.createSpy('on');
 
                 mockParse.andReturn(mockParsed);
@@ -57,7 +57,7 @@ define(
                     jasmine.any(Function)
                 );
                 // Should have been only watch (other tests need this to be true)
-                expect(mockScope.$watch.calls.length).toEqual(0);
+                expect(mockScope.$watch.calls.length).toEqual(1);
             });
 
             it("listens for scroll events", function () {
@@ -66,7 +66,7 @@ define(
                     jasmine.any(Function)
                 );
                 // Should have been only listener (other tests need this to be true)
-                expect(mockElement.on.calls.length).toEqual(0);
+                expect(mockElement.on.calls.length).toEqual(1);
             });
 
             it("publishes initial scroll state", function () {
@@ -76,12 +76,12 @@ define(
 
             it("updates scroll state when scope changes", function () {
                 mockScope.$watch.mostRecentCall.args[1](64);
-                expect(mockElement[0].scrollLeft).toEqual(64);
+                expect(mockElement[0].testProperty).toEqual(64);
             });
 
             it("updates scope when scroll state changes", function () {
-                mockElement[0].scrollLeft = 12321;
+                mockElement[0].testProperty = 12321;
-                mockElement.on.mostRecentCall.args({ target: mockElement[0] });
+                mockElement.on.mostRecentCall.args[1]({ target: mockElement[0] });
                 expect(mockParsed.assign).toHaveBeenCalledWith(12321);
             });