feat(BaseRequestOptions): add merge method to make copies of options

modules/angular2/test/http/base_request_options_spec.ts

@@ -0,0 +1,32 @@
+import {
+  AsyncTestCompleter,
+  beforeEach,
+  ddescribe,
+  describe,
+  expect,
+  iit,
+  inject,
+  it,
+  xit
+} from 'angular2/test_lib';
+import {BaseRequestOptions} from 'angular2/src/http/base_request_options';
+import {RequestMethods, RequestModesOpts} from 'angular2/src/http/enums';
+
+export function main() {
+  describe('BaseRequestOptions', () => {
+    it('should create a new object when calling merge', () => {
+      var options1 = new BaseRequestOptions();
+      var options2 = options1.merge({method: RequestMethods.DELETE});
+      expect(options2).not.toBe(options1);
+      expect(options2.method).toBe(RequestMethods.DELETE);
+    });
+
+    it('should retain previously merged values when merging again', () => {
+      var options1 = new BaseRequestOptions();
+      var options2 = options1.merge({method: RequestMethods.DELETE});
+      var options3 = options2.merge({mode: RequestModesOpts.NoCors}) expect(options3.mode)
+                         .toBe(RequestModesOpts.NoCors);
+      expect(options3.method).toBe(RequestMethods.DELETE);
+    });
+  });
+}