feat($interval): add a service wrapping setInterval

The $interval service simplifies creating and testing recurring tasks.
This service does not increment $browser's outstanding request count,
which means that scenario tests and Protractor tests will not timeout
when a site uses a polling function registered by $interval. Provides
a workaround for #2402.

For unit tests, repeated tasks can be controlled using ngMock$interval's
tick(), tickNext(), and tickAll() functions.

angularFiles.js

@@ -20,6 +20,7 @@ angularFiles = {
     'src/ng/http.js',
     'src/ng/httpBackend.js',
     'src/ng/interpolate.js',
+    'src/ng/interval.js',
     'src/ng/locale.js',
     'src/ng/location.js',
     'src/ng/log.js',

src/AngularPublic.js

@@ -114,6 +114,7 @@ function publishExternalAPI(angular){
         $exceptionHandler: $ExceptionHandlerProvider,
         $filter: $FilterProvider,
         $interpolate: $InterpolateProvider,
+        $interval: $IntervalProvider,
         $http: $HttpProvider,
         $httpBackend: $HttpBackendProvider,
         $location: $LocationProvider,

src/ng/interval.js

@@ -0,0 +1,90 @@
+'use strict';
+
+
+function $IntervalProvider() {
+  this.$get = ['$rootScope', '$window', '$q',
+       function($rootScope,   $window,   $q) {
+    var intervals = {};
+
+
+     /**
+      * @ngdoc function
+      * @name ng.$interval
+      *
+      * @description
+      * Angular's wrapper for `window.setInterval`. The `fn` function is executed every `delay`
+      * milliseconds.
+      *
+      * The return value of registering an interval function is a promise. This promise will be
+      * notified upon each tick of the interval, and will be resolved after `count` iterations, or
+      * run indefinitely if `count` is not defined. The value of the notification will be the
+      * number of iterations that have run.
+      * To cancel an interval, call `$interval.cancel(promise)`.
+      *
+      * In tests you can use {@link ngMock.$interval#flush `$interval.flush(millis)`} to
+      * move forward by `millis` milliseconds and trigger any functions scheduled to run in that
+      * time.
+      *
+      * @param {function()} fn A function that should be called repeatedly.
+      * @param {number} delay Number of milliseconds between each function call.
+      * @param {number=} [count=0] Number of times to repeat. If not set, or 0, will repeat
+      *   indefinitely.
+      * @param {boolean=} [invokeApply=true] If set to `false` skips model dirty checking, otherwise
+      *   will invoke `fn` within the {@link ng.$rootScope.Scope#$apply $apply} block.
+      * @returns {promise} A promise which will be notified on each iteration.
+      */
+    function interval(fn, delay, count, invokeApply) {
+      var setInterval = $window.setInterval,
+          clearInterval = $window.clearInterval;
+
+      var deferred = $q.defer(),
+          promise = deferred.promise,
+          count = (isDefined(count)) ? count : 0,
+          iteration = 0,
+          skipApply = (isDefined(invokeApply) && !invokeApply);
+
+      promise.then(null, null, fn);
+
+      promise.$$intervalId = setInterval(function tick() {
+        deferred.notify(iteration++);
+
+        if (count > 0 && iteration >= count) {
+          deferred.resolve(iteration);
+          clearInterval(promise.$$intervalId);
+          delete intervals[promise.$$intervalId];
+        }
+
+        if (!skipApply) $rootScope.$apply();
+
+      }, delay);
+
+      intervals[promise.$$intervalId] = deferred;
+
+      return promise;
+    }
+
+
+     /**
+      * @ngdoc function
+      * @name ng.$interval#cancel
+      * @methodOf ng.$interval
+      *
+      * @description
+      * Cancels a task associated with the `promise`.
+      *
+      * @param {number} promise Promise returned by the `$interval` function.
+      * @returns {boolean} Returns `true` if the task was successfully canceled.
+      */
+    interval.cancel = function(promise) {
+      if (promise && promise.$$intervalId in intervals) {
+        intervals[promise.$$intervalId].reject('canceled');
+        clearInterval(promise.$$intervalId);
+        delete intervals[promise.$$intervalId];
+        return true;
+      }
+      return false;
+    };
+
+    return interval;
+  }];
+}

src/ngMock/angular-mocks.js

@@ -438,6 +438,119 @@ angular.mock.$LogProvider = function() {
 };
 
 
+/**
+ * @ngdoc service
+ * @name ngMock.$interval
+ *
+ * @description
+ * Mock implementation of the $interval service.
+ *
+ * Use {@link ngMock.$interval#flush `$interval.flush(millis)`} to
+ * move forward by `millis` milliseconds and trigger any functions scheduled to run in that
+ * time.
+ *
+ * @param {function()} fn A function that should be called repeatedly.
+ * @param {number} delay Number of milliseconds between each function call.
+ * @param {number=} [count=0] Number of times to repeat. If not set, or 0, will repeat
+ *   indefinitely.
+ * @param {boolean=} [invokeApply=true] If set to `false` skips model dirty checking, otherwise
+ *   will invoke `fn` within the {@link ng.$rootScope.Scope#$apply $apply} block.
+ * @returns {promise} A promise which will be notified on each iteration.
+ */
+angular.mock.$IntervalProvider = function() {
+  this.$get = ['$rootScope', '$q',
+       function($rootScope,   $q) {
+    var repeatFns = [],
+        nextRepeatId = 0,
+        now = 0;
+
+    var $interval = function(fn, delay, count, invokeApply) {
+      var deferred = $q.defer(),
+          promise = deferred.promise,
+          count = (isDefined(count)) ? count : 0,
+          iteration = 0,
+          skipApply = (isDefined(invokeApply) && !invokeApply);
+
+      promise.then(null, null, fn);
+
+      promise.$$intervalId = nextRepeatId;
+
+      function tick() {
+        deferred.notify(iteration++);
+
+        if (count > 0 && iteration >= count) {
+          var fnIndex;
+          deferred.resolve(iteration);
+
+          angular.forEach(repeatFns, function(fn, index) {
+            if (fn.id === promise.$$intervalId) fnIndex = index;
+          });
+
+          if (fnIndex !== undefined) {
+            repeatFns.splice(fnIndex, 1);
+          }
+        }
+
+        if (!skipApply) $rootScope.$apply();
+      };
+
+      repeatFns.push({
+        nextTime:(now + delay),
+        delay: delay,
+        fn: tick,
+        id: nextRepeatId,
+        deferred: deferred
+      });
+      repeatFns.sort(function(a,b){ return a.nextTime - b.nextTime;});
+
+      nextRepeatId++;
+      return promise;
+    };
+
+    $interval.cancel = function(promise) {
+      var fnIndex;
+
+      angular.forEach(repeatFns, function(fn, index) {
+        if (fn.id === promise.$$intervalId) fnIndex = index;
+      });
+
+      if (fnIndex !== undefined) {
+        repeatFns[fnIndex].deferred.reject('canceled');
+        repeatFns.splice(fnIndex, 1);
+        return true;
+      }
+
+      return false;
+    };
+
+    /**
+     * @ngdoc method
+     * @name ngMock.$interval#flush
+     * @methodOf ngMock.$interval
+     * @description
+     *
+     * Runs interval tasks scheduled to be run in the next `millis` milliseconds.
+     *
+     * @param {number=} millis maximum timeout amount to flush up until.
+     *
+     * @return {number} The amount of time moved forward.
+     */
+    $interval.flush = function(millis) {
+      now += millis;
+      while (repeatFns.length && repeatFns[0].nextTime <= now) {
+        var task = repeatFns[0];
+        task.fn();
+        task.nextTime += task.delay;
+        repeatFns.sort(function(a,b){ return a.nextTime - b.nextTime;});
+      }
+      return millis;
+    };
+
+    return $interval;
+  }];
+};
+
+
 (function() {
   var R_ISO8061_STR = /^(\d{4})-?(\d\d)-?(\d\d)(?:T(\d\d)(?:\:?(\d\d)(?:\:?(\d\d)(?:\.(\d{3}))?)?)?(Z|([+-])(\d\d):?(\d\d)))?$/;
 
@@ -1581,6 +1694,7 @@ angular.module('ngMock', ['ng']).provider({
   $browser: angular.mock.$BrowserProvider,
   $exceptionHandler: angular.mock.$ExceptionHandlerProvider,
   $log: angular.mock.$LogProvider,
+  $interval: angular.mock.$IntervalProvider,
   $httpBackend: angular.mock.$HttpBackendProvider,
   $rootElement: angular.mock.$RootElementProvider
 }).config(function($provide) {

test/ng/intervalSpec.js

@@ -0,0 +1,270 @@
+'use strict';
+
+describe('$interval', function() {
+
+  beforeEach(module(function($provide){
+    var repeatFns = [],
+        nextRepeatId = 0,
+        now = 0,
+        $window;
+
+    $window = {
+      setInterval: function(fn, delay, count) {
+        repeatFns.push({
+          nextTime:(now + delay),
+          delay: delay,
+          fn: fn,
+          id: nextRepeatId,
+        });
+        repeatFns.sort(function(a,b){ return a.nextTime - b.nextTime;});
+
+        return nextRepeatId++;
+      },
+
+      clearInterval: function(id) {
+        var fnIndex;
+
+        angular.forEach(repeatFns, function(fn, index) {
+          if (fn.id === id) fnIndex = index;
+        });
+
+        if (fnIndex !== undefined) {
+          repeatFns.splice(fnIndex, 1);
+          return true;
+        }
+
+        return false;
+      },
+
+      flush: function(millis) {
+        now += millis;
+        while (repeatFns.length && repeatFns[0].nextTime <= now) {
+          var task = repeatFns[0];
+          task.fn();
+          task.nextTime += task.delay;
+          repeatFns.sort(function(a,b){ return a.nextTime - b.nextTime;});
+        }
+        return millis;
+      }
+    };
+
+    $provide.provider('$interval', $IntervalProvider);
+    $provide.value('$window', $window);
+  }));
+
+  it('should run tasks repeatedly', inject(function($interval, $window) {
+    var counter = 0;
+    $interval(function() { counter++; }, 1000);
+
+    expect(counter).toBe(0);
+
+    $window.flush(1000)
+    expect(counter).toBe(1);
+
+    $window.flush(1000);
+
+    expect(counter).toBe(2);
+  }));
+
+  it('should call $apply after each task is executed',
+      inject(function($interval, $rootScope, $window) {
+    var applySpy = spyOn($rootScope, '$apply').andCallThrough();
+
+    $interval(noop, 1000);
+    expect(applySpy).not.toHaveBeenCalled();
+
+    $window.flush(1000);
+    expect(applySpy).toHaveBeenCalledOnce();
+
+    applySpy.reset();
+
+    $interval(noop, 1000);
+    $interval(noop, 1000);
+    $window.flush(1000);
+    expect(applySpy.callCount).toBe(3);
+  }));
+
+
+  it('should NOT call $apply if invokeApply is set to false',
+      inject(function($interval, $rootScope, $window) {
+    var applySpy = spyOn($rootScope, '$apply').andCallThrough();
+
+    $interval(noop, 1000, 0, false);
+    expect(applySpy).not.toHaveBeenCalled();
+
+    $window.flush(2000);
+    expect(applySpy).not.toHaveBeenCalled();
+  }));
+
+
+  it('should allow you to specify the delay time', inject(function($interval, $window) {
+    var counter = 0;
+    $interval(function() { counter++; }, 123);
+
+    expect(counter).toBe(0);
+
+    $window.flush(122);
+    expect(counter).toBe(0);
+
+    $window.flush(1);
+    expect(counter).toBe(1);
+  }));
+
+
+  it('should allow you to specify a number of iterations', inject(function($interval, $window) {
+    var counter = 0;
+    $interval(function() {counter++}, 1000, 2);
+
+    $window.flush(1000);
+    expect(counter).toBe(1);
+    $window.flush(1000);
+    expect(counter).toBe(2);
+    $window.flush(1000);
+    expect(counter).toBe(2);
+  }));
+
+
+  it('should return a promise which will be updated with the count on each iteration',
+      inject(function($interval, $window) {
+    var log = [],
+        promise = $interval(function() { log.push('tick'); }, 1000);
+
+    promise.then(function(value) { log.push('promise success: ' + value); },
+                 function(err) { log.push('promise error: ' + err); },
+                 function(note) { log.push('promise update: ' + note); });
+    expect(log).toEqual([]);
+
+    $window.flush(1000);
+    expect(log).toEqual(['tick', 'promise update: 0']);
+
+    $window.flush(1000);
+    expect(log).toEqual(['tick', 'promise update: 0', 'tick', 'promise update: 1']);
+  }));
+
+
+  it('should return a promise which will be resolved after the specified number of iterations',
+      inject(function($interval, $window) {
+    var log = [],
+        promise = $interval(function() { log.push('tick'); }, 1000, 2);
+
+    promise.then(function(value) { log.push('promise success: ' + value); },
+                 function(err) { log.push('promise error: ' + err); },
+                 function(note) { log.push('promise update: ' + note); });
+    expect(log).toEqual([]);
+
+    $window.flush(1000);
+    expect(log).toEqual(['tick', 'promise update: 0']);
+    $window.flush(1000);
+
+    expect(log).toEqual([
+        'tick', 'promise update: 0', 'tick', 'promise update: 1', 'promise success: 2']);
+
+  }));
+
+
+  describe('exception handling', function() {
+    beforeEach(module(function($exceptionHandlerProvider) {
+      $exceptionHandlerProvider.mode('log');
+    }));
+
+
+    it('should delegate exception to the $exceptionHandler service', inject(
+        function($interval, $exceptionHandler, $window) {
+      $interval(function() { throw "Test Error"; }, 1000);
+      expect($exceptionHandler.errors).toEqual([]);
+
+      $window.flush(1000);
+      expect($exceptionHandler.errors).toEqual(["Test Error"]);
+
+      $window.flush(1000);
+      expect($exceptionHandler.errors).toEqual(["Test Error", "Test Error"]);
+    }));
+
+
+    it('should call $apply even if an exception is thrown in callback', inject(
+        function($interval, $rootScope, $window) {
+      var applySpy = spyOn($rootScope, '$apply').andCallThrough();
+
+      $interval(function() { throw "Test Error"; }, 1000);
+      expect(applySpy).not.toHaveBeenCalled();
+
+      $window.flush(1000);
+      expect(applySpy).toHaveBeenCalled();
+    }));
+
+
+    it('should still update the interval promise when an exception is thrown',
+        inject(function($interval, $window) {
+      var log = [],
+          promise = $interval(function() { throw "Some Error"; }, 1000);
+
+      promise.then(function(value) { log.push('promise success: ' + value); },
+                 function(err) { log.push('promise error: ' + err); },
+                 function(note) { log.push('promise update: ' + note); });
+      $window.flush(1000);
+
+      expect(log).toEqual(['promise update: 0']);
+    }));
+  });
+
+
+  describe('cancel', function() {
+    it('should cancel tasks', inject(function($interval, $window) {
+      var task1 = jasmine.createSpy('task1', 1000),
+          task2 = jasmine.createSpy('task2', 1000),
+          task3 = jasmine.createSpy('task3', 1000),
+          promise1, promise3;
+
+      promise1 = $interval(task1, 200);
+      $interval(task2, 1000);
+      promise3 = $interval(task3, 333);
+
+      $interval.cancel(promise3);
+      $interval.cancel(promise1);
+      $window.flush(1000);
+
+      expect(task1).not.toHaveBeenCalled();
+      expect(task2).toHaveBeenCalledOnce();
+      expect(task3).not.toHaveBeenCalled();
+    }));
+
+
+    it('should cancel the promise', inject(function($interval, $rootScope, $window) {
+      var promise = $interval(noop, 1000),
+          log = [];
+      promise.then(function(value) { log.push('promise success: ' + value); },
+                 function(err) { log.push('promise error: ' + err); },
+                 function(note) { log.push('promise update: ' + note); });
+      expect(log).toEqual([]);
+
+      $window.flush(1000);
+      $interval.cancel(promise);
+      $window.flush(1000);
+      $rootScope.$apply(); // For resolving the promise -
+                           // necessary since q uses $rootScope.evalAsync.
+
+      expect(log).toEqual(['promise update: 0', 'promise error: canceled']);
+    }));
+
+
+    it('should return true if a task was successfully canceled',
+        inject(function($interval, $window) {
+      var task1 = jasmine.createSpy('task1'),
+          task2 = jasmine.createSpy('task2'),
+          promise1, promise2;
+
+      promise1 = $interval(task1, 1000, 1);
+      $window.flush(1000);
+      promise2 = $interval(task2, 1000, 1);
+
+      expect($interval.cancel(promise1)).toBe(false);
+      expect($interval.cancel(promise2)).toBe(true);
+    }));
+
+
+    it('should not throw a runtime exception when given an undefined promise',
+        inject(function($interval) {
+      expect($interval.cancel()).toBe(false);
+    }));
+  });
+});

test/ng/timeoutSpec.js

@@ -165,6 +165,20 @@ describe('$timeout', function() {
     }));
 
 
+    it('should cancel the promise', inject(function($timeout, log) {
+      var promise = $timeout(noop);
+      promise.then(function(value) { log('promise success: ' + value); },
+                 function(err) { log('promise error: ' + err); },
+                 function(note) { log('promise update: ' + note); });
+      expect(log).toEqual([]);
+
+      $timeout.cancel(promise);
+      $timeout.flush();
+
+      expect(log).toEqual(['promise error: canceled']);
+    }));
+
+
     it('should return true if a task was successfully canceled', inject(function($timeout) {
       var task1 = jasmine.createSpy('task1'),
           task2 = jasmine.createSpy('task2'),

test/ngMock/angular-mocksSpec.js

@@ -283,6 +283,241 @@ describe('ngMock', function() {
   });
 
 
+  describe('$interval', function() {
+    it('should run tasks repeatedly', inject(function($interval) {
+      var counter = 0;
+      $interval(function() { counter++; }, 1000);
+
+      expect(counter).toBe(0);
+
+      $interval.flush(1000);
+      expect(counter).toBe(1);
+
+      $interval.flush(1000);
+
+      expect(counter).toBe(2);
+    }));
+
+
+    it('should call $apply after each task is executed', inject(function($interval, $rootScope) {
+      var applySpy = spyOn($rootScope, '$apply').andCallThrough();
+
+      $interval(noop, 1000);
+      expect(applySpy).not.toHaveBeenCalled();
+
+      $interval.flush(1000);
+      expect(applySpy).toHaveBeenCalledOnce();
+
+      applySpy.reset();
+
+      $interval(noop, 1000);
+      $interval(noop, 1000);
+      $interval.flush(1000);
+      expect(applySpy.callCount).toBe(3);
+    }));
+
+
+    it('should NOT call $apply if invokeApply is set to false',
+        inject(function($interval, $rootScope) {
+      var applySpy = spyOn($rootScope, '$apply').andCallThrough();
+
+      $interval(noop, 1000, 0, false);
+      expect(applySpy).not.toHaveBeenCalled();
+
+      $interval.flush(2000);
+      expect(applySpy).not.toHaveBeenCalled();
+    }));
+
+
+    it('should allow you to specify the delay time', inject(function($interval) {
+      var counter = 0;
+      $interval(function() { counter++; }, 123);
+
+      expect(counter).toBe(0);
+
+      $interval.flush(122);
+      expect(counter).toBe(0);
+
+      $interval.flush(1);
+      expect(counter).toBe(1);
+    }));
+
+
+    it('should allow you to specify a number of iterations', inject(function($interval) {
+      var counter = 0;
+      $interval(function() {counter++}, 1000, 2);
+
+      $interval.flush(1000);
+      expect(counter).toBe(1);
+      $interval.flush(1000);
+      expect(counter).toBe(2);
+      $interval.flush(1000);
+      expect(counter).toBe(2);
+    }));
+
+
+    describe('flush', function() {
+      it('should move the clock forward by the specified time', inject(function($interval) {
+        var counterA = 0;
+        var counterB = 0;
+        $interval(function() { counterA++; }, 100);
+        $interval(function() { counterB++; }, 401);
+
+        $interval.flush(200);
+        expect(counterA).toEqual(2);
+
+        $interval.flush(201);
+        expect(counterA).toEqual(4);
+        expect(counterB).toEqual(1);
+      }));
+    });
+
+
+    it('should return a promise which will be updated with the count on each iteration',
+        inject(function($interval) {
+      var log = [],
+          promise = $interval(function() { log.push('tick'); }, 1000);
+
+      promise.then(function(value) { log.push('promise success: ' + value); },
+                   function(err) { log.push('promise error: ' + err); },
+                   function(note) { log.push('promise update: ' + note); });
+      expect(log).toEqual([]);
+
+      $interval.flush(1000);
+      expect(log).toEqual(['tick', 'promise update: 0']);
+
+      $interval.flush(1000);
+      expect(log).toEqual(['tick', 'promise update: 0', 'tick', 'promise update: 1']);
+    }));
+
+
+    it('should return a promise which will be resolved after the specified number of iterations',
+        inject(function($interval) {
+      var log = [],
+          promise = $interval(function() { log.push('tick'); }, 1000, 2);
+
+      promise.then(function(value) { log.push('promise success: ' + value); },
+                   function(err) { log.push('promise error: ' + err); },
+                   function(note) { log.push('promise update: ' + note); });
+      expect(log).toEqual([]);
+
+      $interval.flush(1000);
+      expect(log).toEqual(['tick', 'promise update: 0']);
+      $interval.flush(1000);
+
+      expect(log).toEqual([
+          'tick', 'promise update: 0', 'tick', 'promise update: 1', 'promise success: 2']);
+
+    }));
+
+
+    describe('exception handling', function() {
+      beforeEach(module(function($exceptionHandlerProvider) {
+        $exceptionHandlerProvider.mode('log');
+      }));
+
+
+      it('should delegate exception to the $exceptionHandler service', inject(
+          function($interval, $exceptionHandler) {
+        $interval(function() { throw "Test Error"; }, 1000);
+        expect($exceptionHandler.errors).toEqual([]);
+
+        $interval.flush(1000);
+        expect($exceptionHandler.errors).toEqual(["Test Error"]);
+
+        $interval.flush(1000);
+        expect($exceptionHandler.errors).toEqual(["Test Error", "Test Error"]);
+      }));
+
+
+      it('should call $apply even if an exception is thrown in callback', inject(
+          function($interval, $rootScope) {
+        var applySpy = spyOn($rootScope, '$apply').andCallThrough();
+
+        $interval(function() { throw "Test Error"; }, 1000);
+        expect(applySpy).not.toHaveBeenCalled();
+
+        $interval.flush(1000);
+        expect(applySpy).toHaveBeenCalled();
+      }));
+
+
+      it('should still update the interval promise when an exception is thrown',
+          inject(function($interval) {
+        var log = [],
+            promise = $interval(function() { throw "Some Error"; }, 1000);
+
+        promise.then(function(value) { log.push('promise success: ' + value); },
+                   function(err) { log.push('promise error: ' + err); },
+                   function(note) { log.push('promise update: ' + note); });
+        $interval.flush(1000);
+
+        expect(log).toEqual(['promise update: 0']);
+      }));
+    });
+
+
+    describe('cancel', function() {
+      it('should cancel tasks', inject(function($interval) {
+        var task1 = jasmine.createSpy('task1', 1000),
+            task2 = jasmine.createSpy('task2', 1000),
+            task3 = jasmine.createSpy('task3', 1000),
+            promise1, promise3;
+
+        promise1 = $interval(task1, 200);
+        $interval(task2, 1000);
+        promise3 = $interval(task3, 333);
+
+        $interval.cancel(promise3);
+        $interval.cancel(promise1);
+        $interval.flush(1000);
+
+        expect(task1).not.toHaveBeenCalled();
+        expect(task2).toHaveBeenCalledOnce();
+        expect(task3).not.toHaveBeenCalled();
+      }));
+
+
+      it('should cancel the promise', inject(function($interval, $rootScope) {
+        var promise = $interval(noop, 1000),
+            log = [];
+        promise.then(function(value) { log.push('promise success: ' + value); },
+                   function(err) { log.push('promise error: ' + err); },
+                   function(note) { log.push('promise update: ' + note); });
+        expect(log).toEqual([]);
+
+        $interval.flush(1000);
+        $interval.cancel(promise);
+        $interval.flush(1000);
+        $rootScope.$apply(); // For resolving the promise -
+                             // necessary since q uses $rootScope.evalAsync.
+
+        expect(log).toEqual(['promise update: 0', 'promise error: canceled']);
+      }));
+
+
+      it('should return true if a task was successfully canceled', inject(function($interval) {
+        var task1 = jasmine.createSpy('task1'),
+            task2 = jasmine.createSpy('task2'),
+            promise1, promise2;
+
+        promise1 = $interval(task1, 1000, 1);
+        $interval.flush(1000);
+        promise2 = $interval(task2, 1000, 1);
+
+        expect($interval.cancel(promise1)).toBe(false);
+        expect($interval.cancel(promise2)).toBe(true);
+      }));
+
+
+      it('should not throw a runtime exception when given an undefined promise',
+          inject(function($interval) {
+        expect($interval.cancel()).toBe(false);
+      }));
+    });
+  });
+
+
   describe('defer', function() {
     var browser, log;
     beforeEach(inject(function($browser) {