[Core] Complete spec for capailities

Complete specs for capabilities introduced in platform/core,
part of ongoing transition of this bundle. WTD-573.

platform/core/test/capabilities/MutationCapabilitySpec.js

@@ -9,7 +9,50 @@ define(
         "use strict";
 
         describe("The mutation capability", function () {
+            var testModel,
+                domainObject = { getModel: function () { return testModel; } },
+                mutation;
 
+            function mockPromise(value) {
+                return {
+                    then: function (callback) {
+                        return (value && value.then) ?
+                                value : mockPromise(callback(value));
+                    }
+                };
+            }
+
+            beforeEach(function () {
+                testModel = { number: 6 };
+                mutation = new MutationCapability(
+                    { when: mockPromise }, // $q
+                    domainObject
+                );
+            });
+
+            it("allows mutation of a model", function () {
+                mutation.invoke(function (m) {
+                    m.number = m.number * 7;
+                });
+                expect(testModel.number).toEqual(42);
+            });
+
+            it("allows setting a model", function () {
+                mutation.invoke(function (m) {
+                    return { someKey: "some value" };
+                });
+                expect(testModel.number).toBeUndefined();
+                expect(testModel.someKey).toEqual("some value");
+            });
+
+            it("allows model mutation to be aborted", function () {
+                mutation.invoke(function (m) {
+                    m.number = m.number * 7;
+                    return false; // Should abort change
+                });
+                // Number should not have been changed
+                expect(testModel.number).toEqual(6);
+            });
         });
     }
 );