fix(life_cycle): throw when recursively reentering LifeCycle.tick

modules/angular2/src/core/life_cycle/life_cycle.ts

@@ -2,7 +2,7 @@ import {Injectable} from 'angular2/di';
 import {ChangeDetector} from 'angular2/change_detection';
 import {NgZone} from 'angular2/src/core/zone/ng_zone';
 import {ExceptionHandler} from 'angular2/src/core/exception_handler';
-import {isPresent} from 'angular2/src/facade/lang';
+import {isPresent, BaseException} from 'angular2/src/facade/lang';
 
 /**
  * Provides access to explicitly trigger change detection in an application.
@@ -36,6 +36,7 @@ export class LifeCycle {
   _errorHandler;
   _changeDetector: ChangeDetector;
   _enforceNoNewChanges: boolean;
+  _runningTick: boolean = false;
 
   constructor(exceptionHandler: ExceptionHandler, changeDetector: ChangeDetector = null,
               enforceNoNewChanges: boolean = false) {
@@ -75,9 +76,18 @@ export class LifeCycle {
    *
    */
   tick() {
+    if (this._runningTick) {
+      throw new BaseException("LifeCycle.tick is called recursively");
+    }
+
+    try {
+      this._runningTick = true;
       this._changeDetector.detectChanges();
       if (this._enforceNoNewChanges) {
         this._changeDetector.checkNoChanges();
       }
+    } finally {
+      this._runningTick = false;
+    }
   }
 }

modules/angular2/test/core/life_cycle/life_cycle_spec.ts

@@ -0,0 +1,38 @@
+import {
+  ddescribe,
+  describe,
+  it,
+  iit,
+  xit,
+  expect,
+  beforeEach,
+  afterEach,
+  el,
+  AsyncTestCompleter,
+  fakeAsync,
+  tick,
+  SpyObject,
+  inject,
+  proxy
+  } from 'angular2/test_lib';
+import {LifeCycle} from 'angular2/src/core/life_cycle/life_cycle';
+import {ChangeDetector} from 'angular2/change_detection';
+import {IMPLEMENTS} from 'angular2/src/facade/lang';
+
+@proxy
+@IMPLEMENTS(ChangeDetector)
+class SpyChangeDetector extends SpyObject {
+  constructor() { super(ChangeDetector); }
+  noSuchMethod(m) { return super.noSuchMethod(m) }
+}
+
+export function main() {
+  describe("LifeCycle", () => {
+    it("should throw when reentering tick", () => {
+      var cd = <any>new SpyChangeDetector();
+      var lc = new LifeCycle(null, cd, false);
+      cd.spy("detectChanges").andCallFake(() => lc.tick());
+      expect(() => lc.tick()).toThrowError("LifeCycle.tick is called recursively");
+    });
+  });
+}