test: introduce TemplateResolver mock

Closes #768

modules/angular2/src/mock/template_resolver_mock.js

@@ -0,0 +1,28 @@
+import {Map, MapWrapper, ListWrapper} from 'angular2/src/facade/collection';
+import {Type, isPresent} from 'angular2/src/facade/lang';
+
+import {Template} from 'angular2/src/core/annotations/template';
+import {TemplateResolver} from 'angular2/src/core/compiler/template_resolver';
+
+export class MockTemplateResolver extends TemplateResolver {
+  _cmpTemplates: Map;
+
+  constructor() {
+    super();
+    this._cmpTemplates = MapWrapper.create();
+  }
+
+  setTemplate(component: Type, template: Template) {
+    MapWrapper.set(this._cmpTemplates, component, template);
+  }
+
+  resolve(component: Type): Template {
+    var override = MapWrapper.get(this._cmpTemplates, component);
+
+    if (isPresent(override)) {
+      return override;
+    }
+
+    return super.resolve(component);
+  }
+}