refactor(example): refactor forward_ref example into a spec and unignore example specs (#11088)

modules/@angular/examples/core/di/ts/forward_ref/forward_ref.ts

@@ -1,35 +0,0 @@
-/**
- * @license
- * Copyright Google Inc. All Rights Reserved.
- *
- * Use of this source code is governed by an MIT-style license that can be
- * found in the LICENSE file at https://angular.io/license
- */
-
-import {ForwardRefFn, Inject, ReflectiveInjector, forwardRef, resolveForwardRef} from '@angular/core';
-
-
-// #docregion forward_ref_fn
-var ref = forwardRef(() => Lock);
-// #enddocregion
-
-// #docregion forward_ref
-class Door {
-  lock: Lock;
-  constructor(@Inject(forwardRef(() => Lock)) lock: Lock) { this.lock = lock; }
-}
-
-// Only at this point Lock is defined.
-class Lock {}
-
-var injector = ReflectiveInjector.resolveAndCreate([Door, Lock]);
-var door = injector.get(Door);
-expect(door instanceof Door).toBe(true);
-expect(door.lock instanceof Lock).toBe(true);
-// #enddocregion
-
-// #docregion resolve_forward_ref
-ref = forwardRef(() => 'refValue');
-expect(resolveForwardRef(ref)).toEqual('refValue');
-expect(resolveForwardRef('regularValue')).toEqual('regularValue');
-// #enddocregion

modules/@angular/examples/core/di/ts/forward_ref/forward_ref_spec.ts

@@ -0,0 +1,50 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {ForwardRefFn, Inject, ReflectiveInjector, forwardRef, resolveForwardRef} from '@angular/core';
+
+export function main() {
+  describe('forwardRef examples', () => {
+    it('ForwardRefFn example works', () => {
+      // #docregion forward_ref_fn
+      let ref = forwardRef(() => Lock);
+      // #enddocregion
+      expect(ref).not.toBeNull();
+
+      class Lock {}
+    });
+
+    it('can be used to inject a class defined later', () => {
+      // #docregion forward_ref
+      class Door {
+        lock: Lock;
+
+        // Door attempts to inject Lock, despite it not being defined yet.
+        // forwardRef makes this possible.
+        constructor(@Inject(forwardRef(() => Lock)) lock: Lock) { this.lock = lock; }
+      }
+
+      // Only at this point Lock is defined.
+      class Lock {}
+
+      let injector = ReflectiveInjector.resolveAndCreate([Door, Lock]);
+      let door = injector.get(Door);
+      expect(door instanceof Door).toBeTruthy();
+      expect(door.lock instanceof Lock).toBeTruthy();
+      // #enddocregion
+    });
+
+    it('can be unwrapped', () => {
+      // #docregion resolve_forward_ref
+      let ref = forwardRef(() => 'refValue');
+      expect(resolveForwardRef(ref)).toEqual('refValue');
+      expect(resolveForwardRef('regularValue')).toEqual('regularValue');
+      // #enddocregion
+    });
+  });
+}