首先，我想说你的控制器实现应该是这样的：

$scope.qPromiseCall = function() {

    var timeoutPromise = $timeout(function() {
      canceler.resolve(); //aborts the request when timed out
      console.log("Timed out");
    }, 250); //we set a timeout for 250ms and store the promise in order to be cancelled later if the data does not arrive within 250ms

    var canceler = $q.defer();
    $http.get("data.js", {timeout: canceler.promise} ).success(function(data){
      console.log(data);

      $timeout.cancel(timeoutPromise); //cancel the timer when we get a response within 250ms
    });
  }

您的测试：

it('Timeout occurs', function() {
    spyOn(console, 'log');
    $scope.qPromiseCall();
    $timeout.flush(251); //timeout occurs after 251ms
    //there is no http response to flush because we cancel the response in our code. Trying to  call $httpBackend.flush(); will throw an exception and fail the test
    $scope.$apply();
    expect(console.log).toHaveBeenCalledWith("Timed out");
  })

  it('Timeout does not occur', function() {
    spyOn(console, 'log');
    $scope.qPromiseCall();
    $timeout.flush(230); //set the timeout to occur after 230ms
    $httpBackend.flush(); //the response arrives before the timeout
    $scope.$apply();
    expect(console.log).not.toHaveBeenCalledWith("Timed out");
  })

演示

另一个例子promiseService.getPromise：

app.factory("promiseService", function($q,$timeout,$http) {
  return {
    getPromise: function() {
      var timeoutPromise = $timeout(function() {
        console.log("Timed out");

        defer.reject("Timed out"); //reject the service in case of timeout
      }, 250);

      var defer = $q.defer();//in a real implementation, we would call an async function and 
                             // resolve the promise after the async function finishes

      $timeout(function(data){//simulating an asynch function. In your app, it could be
                              // $http or something else (this external service should be injected
                              //so that we can mock it in unit testing)
        $timeout.cancel(timeoutPromise); //cancel the timeout

         defer.resolve(data);
      });

      return defer.promise;
    }
  };
});

app.controller('MainCtrl', function($scope, $timeout, promiseService) {

  $scope.qPromiseCall = function() {

    promiseService.getPromise().then(function(data) {
      console.log(data); 
    });//you could pass a second callback to handle error cases including timeout

  }
});

您的测试类似于上面的示例：

it('Timeout occurs', function() {
    spyOn(console, 'log');
    spyOn($timeout, 'cancel');
    $scope.qPromiseCall();
    $timeout.flush(251); //set it to timeout
    $scope.$apply();
    expect(console.log).toHaveBeenCalledWith("Timed out");
  //expect($timeout.cancel).not.toHaveBeenCalled(); 
  //I also use $timeout to simulate in the code so I cannot check it here because the $timeout is flushed
  //In real app, it is a different service
  })

it('Timeout does not occur', function() {
    spyOn(console, 'log');
    spyOn($timeout, 'cancel');
    $scope.qPromiseCall();
    $timeout.flush(230);//not timeout
    $scope.$apply();
    expect(console.log).not.toHaveBeenCalledWith("Timed out");
    expect($timeout.cancel).toHaveBeenCalled(); //also need to check whether cancel is called
  })

演示