在angularjs中为promise设置超时处理程序

Question

我正在尝试在我的控制器中设置超时,以便如果在250ms内没有收到响应,则应该失败.我已将单位测试设置为超时10000,以便满足此条件,任何人都可以指出我正确的方向吗？(编辑我试图实现这一点,而不使用我知道提供超时功能的$ http服务)

(编辑 - 我的其他单元测试失败了,因为我没有调用timeout.flush,现在我只需要在promiseService.getPromise()返回未定义的promise时获取超时消息.我已经删除了来自问题的早期代码).

promiseService(promise是一个测试套件变量,允许我在应用之前对每个测试套件中的promise使用不同的行为,例如拒绝一个,成功另一个)

    mockPromiseService = jasmine.createSpyObj('promiseService', ['getPromise']);
    mockPromiseService.getPromise.andCallFake( function() {
        promise = $q.defer();
        return promise.promise;
    })

正在测试的控制器功能 -

$scope.qPromiseCall = function() {
    var timeoutdata = null;
    $timeout(function() {
        promise = promiseService.getPromise();
        promise.then(function (data) {
                timeoutdata = data;
                if (data == "promise success!") {
                    console.log("success");
                } else {
                    console.log("function failure");
                }
            }, function (error) {
                console.log("promise failure")
            }

        )
    }, 250).then(function (data) {
        if(typeof timeoutdata === "undefined" ) {
            console.log("Timed out")
        }
    },function( error ){
        console.log("timed out!");
    });
}

测试(通常我在这里解决或拒绝承诺但是没有设置它我正在模拟超时)

it('Timeout logs promise failure', function(){
    spyOn(console, 'log');
    scope.qPromiseCall();
    $timeout.flush(251);
    $rootScope.$apply();
    expect(console.log).toHaveBeenCalledWith("Timed out");
})

Answer 1

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
    });
  }

你的测试:

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");
  })

DEMO

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

  }
});

您的测试与上面的示例类似:

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
  })

DEMO

Answer 2

"失败承诺除非在指定的时间范围内解决"的行为似乎是重构为单独服务/工厂的理想选择.这应该使新服务/工厂和控制器中的代码更清晰,更可重用.

控制器,我假设只是设置范围的成功/失败:

app.controller('MainCtrl', function($scope, failUnlessResolvedWithin, myPromiseService) {
  failUnlessResolvedWithin(function() {
    return myPromiseService.getPromise();
  }, 250).then(function(result) {
    $scope.result = result;
  }, function(error) {
    $scope.error = error;
  });
});

而工厂,failUnlessResolvedWithin创造了一个新的承诺,有效地"拦截"传递功能的承诺.它返回一个复制其解析/拒绝行为的新的,除了它还拒绝了在超时内未解析的promise:

app.factory('failUnlessResolvedWithin', function($q, $timeout) {

  return function(func, time) {
    var deferred = $q.defer();

    $timeout(function() {
      deferred.reject('Not resolved within ' + time);
    }, time);

    $q.when(func()).then(function(results) {
      deferred.resolve(results);
    }, function(failure) {
      deferred.reject(failure);
    });

    return deferred.promise;
  };
});

这些测试有点棘手(很长),但你可以在http://plnkr.co/edit/3e4htwMI5fh595ggZY7h?p=preview看到它们.测试的要点是

• 控制器的测试failUnlessResolvedWithin通过调用来模拟$timeout.

  $provide.value('failUnlessResolvedWithin', function(func, time) {
    return $timeout(func, time);
  });
  

  这是可能的,因为'failUnlessResolvedWithin'(故意)在语法上等同于$timeout,并且因为$timeout提供了flush测试各种情况的函数.

• 服务本身的测试使用调用$timeout.flush来测试在超时之前/之后解析/拒绝的原始承诺的各种情况的行为.

  beforeEach(function() {
    failUnlessResolvedWithin(func, 2)
    .catch(function(error) {
      failResult = error;
    });
  });
  
  beforeEach(function() {
    $timeout.flush(3);
    $rootScope.$digest();
  });
  
  it('the failure callback should be called with the error from the service', function() {
    expect(failResult).toBe('Not resolved within 2');
  });   
  

你可以在http://plnkr.co/edit/3e4htwMI5fh595ggZY7h?p=preview上看到这一切.