[Core] Add test cases for CachingModelDecorator

WTD-1033.

platform/core/test/models/CachingModelDecoratorSpec.js

@@ -6,6 +6,55 @@ define(
         "use strict";
 
         describe("The caching model decorator", function () {
+            var mockModelService,
+                mockCallback,
+                testModels,
+                decorator;
+
+            function asPromise(value) {
+                return (value || {}).then ? value : {
+                    then: function (callback) {
+                        return asPromise(callback(value));
+                    }
+                };
+            }
+
+            beforeEach(function () {
+                mockCallback = jasmine.createSpy();
+                mockModelService = jasmine.createSpyObj('modelService', ['getModels']);
+                testModels = {
+                    a: { someKey: "some value" },
+                    b: { someOtherKey: "some other value" }
+                };
+                mockModelService.getModels.andReturn(asPromise(testModels));
+                decorator = new CachingModelDecorator(mockModelService);
+            });
+
+            it("loads models from its wrapped model service", function () {
+                decorator.getModels(['a', 'b']).then(mockCallback);
+                expect(mockCallback).toHaveBeenCalledWith(testModels);
+            });
+
+            it("does not try to reload cached models", function () {
+                mockModelService.getModels.andReturn(asPromise({ a: testModels.a }));
+                decorator.getModels(['a']);
+                mockModelService.getModels.andReturn(asPromise(testModels));
+                decorator.getModels(['a', 'b']);
+                expect(mockModelService.getModels).not.toHaveBeenCalledWith(['a', 'b']);
+                expect(mockModelService.getModels.mostRecentCall.args[0]).toEqual(['b']);
+            });
+
+            it("does not call its wrapped model service if not needed", function () {
+                decorator.getModels(['a', 'b']);
+                expect(mockModelService.getModels.calls.length).toEqual(1);
+                decorator.getModels(['a', 'b']).then(mockCallback);
+                expect(mockModelService.getModels.calls.length).toEqual(1);
+                // Verify that we still got back our models, even though
+                // no new call to the wrapped service was made
+                expect(mockCallback).toHaveBeenCalledWith(testModels);
+            });
+
+
         });
     }
 );