fix(fakeAsync): have fakeAsync use Proxy zone. (#10797)

Closes #10503

It is possible for code in `beforeEach` to capture and fork a zone
(for example creating `NgZone` in `beforeEach`). Subsequently the code
in `it` may chose to do `fakeAsync`. The issue is that because the
code in `it` can use `NgZone` from the `beforeEach`. it effectively can
escape the `fakeAsync` zone. A solution is to run all of the test in
`ProxyZone` which allows a test to dynamically replace the rules at any
time. This allows the `beforeEach` to fork a zone, and then `it` to
retroactively became `fakeAsync` zone.

modules/@angular/core/testing/async.ts

@@ -32,7 +32,13 @@ export function async(fn: Function): (done: any) => any {
   // function when asynchronous activity is finished.
   if (_global.jasmine) {
     return (done: any) => {
-      runInTestZone(fn, done, (err: string | Error) => {
+      if (!done) {
+        // if we run beforeEach in @angular/core/testing/testing_internal then we get no done
+        // fake it here and assume sync.
+        done = function() {};
+        done.fail = function(e: any) { throw e; };
+      }
+      runInTestZone(fn, done, (err: any) => {
         if (typeof err === 'string') {
           return done.fail(new Error(<string>err));
         } else {
@@ -50,13 +56,52 @@ export function async(fn: Function): (done: any) => any {
 }
 
 function runInTestZone(fn: Function, finishCallback: Function, failCallback: Function) {
-  var AsyncTestZoneSpec = (Zone as any /** TODO #9100 */)['AsyncTestZoneSpec'];
+  const currentZone = Zone.current;
+  var AsyncTestZoneSpec = (Zone as any)['AsyncTestZoneSpec'];
   if (AsyncTestZoneSpec === undefined) {
     throw new Error(
         'AsyncTestZoneSpec is needed for the async() test helper but could not be found. ' +
         'Please make sure that your environment includes zone.js/dist/async-test.js');
   }
-  var testZoneSpec = new AsyncTestZoneSpec(finishCallback, failCallback, 'test');
-  var testZone = Zone.current.fork(testZoneSpec);
-  return testZone.run(fn);
+  const ProxyZoneSpec = (Zone as any)['ProxyZoneSpec'] as {
+    get(): {setDelegate(spec: ZoneSpec): void; getDelegate(): ZoneSpec;};
+    assertPresent: () => void;
+  };
+  if (ProxyZoneSpec === undefined) {
+    throw new Error(
+        'ProxyZoneSpec is needed for the async() test helper but could not be found. ' +
+        'Please make sure that your environment includes zone.js/dist/proxy-zone.js');
+  }
+  const proxyZoneSpec = ProxyZoneSpec.get();
+  ProxyZoneSpec.assertPresent();
+  // We need to create the AsyncTestZoneSpec outside the ProxyZone.
+  // If we do it in ProxyZone then we will get to infinite recursion.
+  const proxyZone = Zone.current.getZoneWith('ProxyZoneSpec');
+  const previousDelegate = proxyZoneSpec.getDelegate();
+  proxyZone.parent.run(() => {
+    var testZoneSpec: ZoneSpec = new AsyncTestZoneSpec(
+        () => {
+          // Need to restore the original zone.
+          currentZone.run(() => {
+            if (proxyZoneSpec.getDelegate() == testZoneSpec) {
+              // Only reset the zone spec if it's sill this one. Otherwise, assume it's OK.
+              proxyZoneSpec.setDelegate(previousDelegate);
+            }
+            finishCallback();
+          });
+        },
+        (error: any) => {
+          // Need to restore the original zone.
+          currentZone.run(() => {
+            if (proxyZoneSpec.getDelegate() == testZoneSpec) {
+              // Only reset the zone spec if it's sill this one. Otherwise, assume it's OK.
+              proxyZoneSpec.setDelegate(previousDelegate);
+            }
+            failCallback(error);
+          });
+        },
+        'test');
+    proxyZoneSpec.setDelegate(testZoneSpec);
+  });
+  return Zone.current.runGuarded(fn);
 }

modules/@angular/core/testing/fake_async.ts

@@ -8,9 +8,14 @@
 
 import {BaseException} from '../index';
 
-let _FakeAsyncTestZoneSpecType = (Zone as any /** TODO #9100 */)['FakeAsyncTestZoneSpec'];
 
-let _fakeAsyncZone: Zone = null;
+const FakeAsyncTestZoneSpec = (Zone as any)['FakeAsyncTestZoneSpec'];
+type ProxyZoneSpec = {
+  setDelegate(delegateSpec: ZoneSpec): void; getDelegate(): ZoneSpec; resetDelegate(): void;
+};
+const ProxyZoneSpec: {get(): ProxyZoneSpec; assertPresent: () => ProxyZoneSpec} =
+    (Zone as any)['ProxyZoneSpec'];
+
 let _fakeAsyncTestZoneSpec: any = null;
 
 /**
@@ -20,8 +25,8 @@ let _fakeAsyncTestZoneSpec: any = null;
  * @experimental
  */
 export function resetFakeAsyncZone() {
-  _fakeAsyncZone = null;
   _fakeAsyncTestZoneSpec = null;
+  ProxyZoneSpec.assertPresent().resetDelegate();
 }
 
 let _inFakeAsyncCall = false;
@@ -45,26 +50,30 @@ let _inFakeAsyncCall = false;
  * @experimental
  */
 export function fakeAsync(fn: Function): (...args: any[]) => any {
-  return function(...args: any[] /** TODO #9100 */) {
+  return function(...args: any[]) {
+    const proxyZoneSpec = ProxyZoneSpec.assertPresent();
     if (_inFakeAsyncCall) {
       throw new BaseException('fakeAsync() calls can not be nested');
     }
     _inFakeAsyncCall = true;
     try {
-      if (!_fakeAsyncZone) {
-        if (Zone.current.get('FakeAsyncTestZoneSpec') != null) {
+      if (!_fakeAsyncTestZoneSpec) {
+        if (proxyZoneSpec.getDelegate() instanceof FakeAsyncTestZoneSpec) {
           throw new BaseException('fakeAsync() calls can not be nested');
         }
 
-        _fakeAsyncTestZoneSpec = new _FakeAsyncTestZoneSpecType();
-        _fakeAsyncZone = Zone.current.fork(_fakeAsyncTestZoneSpec);
+        _fakeAsyncTestZoneSpec = new FakeAsyncTestZoneSpec();
       }
 
-      let res = _fakeAsyncZone.run(() => {
-        let res = fn(...args);
+      let res: any;
+      const lastProxyZoneSpec = proxyZoneSpec.getDelegate();
+      proxyZoneSpec.setDelegate(_fakeAsyncTestZoneSpec);
+      try {
+        res = fn(...args);
         flushMicrotasks();
-        return res;
-      });
+      } finally {
+        proxyZoneSpec.setDelegate(lastProxyZoneSpec);
+      }
 
       if (_fakeAsyncTestZoneSpec.pendingPeriodicTimers.length > 0) {
         throw new BaseException(

modules/@angular/core/testing/testing_internal.ts

@@ -34,7 +34,7 @@ var jsmIt = _global.it;
 var jsmIIt = _global.fit;
 var jsmXIt = _global.xit;
 
-var runnerStack: any[] /** TODO #9100 */ = [];
+var runnerStack: BeforeEachRunner[] = [];
 var inIt = false;
 jasmine.DEFAULT_TIMEOUT_INTERVAL = 3000;
 var globalTimeOut = jasmine.DEFAULT_TIMEOUT_INTERVAL;
@@ -62,7 +62,7 @@ class BeforeEachRunner {
 // Reset the test providers before each test
 jsmBeforeEach(() => { testBed.resetTestingModule(); });
 
-function _describe(jsmFn: any /** TODO #9100 */, ...args: any[] /** TODO #9100 */) {
+function _describe(jsmFn: Function, ...args: any[]) {
   var parentRunner = runnerStack.length === 0 ? null : runnerStack[runnerStack.length - 1];
   var runner = new BeforeEachRunner(parentRunner);
   runnerStack.push(runner);
@@ -71,15 +71,15 @@ function _describe(jsmFn: any /** TODO #9100 */, ...args: any[] /** TODO #9100 *
   return suite;
 }
 
-export function describe(...args: any[] /** TODO #9100 */): void {
+export function describe(...args: any[]): void {
   return _describe(jsmDescribe, ...args);
 }
 
-export function ddescribe(...args: any[] /** TODO #9100 */): void {
+export function ddescribe(...args: any[]): void {
   return _describe(jsmDDescribe, ...args);
 }
 
-export function xdescribe(...args: any[] /** TODO #9100 */): void {
+export function xdescribe(...args: any[]): void {
   return _describe(jsmXDescribe, ...args);
 }
 
@@ -105,7 +105,7 @@ export function beforeEach(fn: Function): void {
  *     {provide: SomeToken, useValue: myValue},
  *   ]);
  */
-export function beforeEachProviders(fn: any /** TODO #9100 */): void {
+export function beforeEachProviders(fn: Function): void {
   jsmBeforeEach(() => {
     var providers = fn();
     if (!providers) return;
@@ -128,7 +128,7 @@ export function addProviders(providers: Array<any>): void {
 /**
  * @deprecated
  */
-export function beforeEachBindings(fn: any /** TODO #9100 */): void {
+export function beforeEachBindings(fn: Function): void {
   beforeEachProviders(fn);
 }