如何測試在觸發事件后是否調用了函數？

Question

在FooView觸發了自定義事件..

// views/foo_view.js

this.trigger("something:happened");

關聯的FooController綁定一個處理程序來處理事件......

// controller/foo_controller.js

initialize: function() {
  this.fooView = new FooView();
  this.fooView.bind("something:happened", this.onSomethingHappened, this);
}

onSomethingHappened: function(event) {
  // Do something else.
}

為了測試事件處理，我將為Jasmine編寫以下測試：

it("should do something else when something happens", function() {
  var fooController = new FooController();
  spyOn(fooController, "onSomethingHappened");
  fooController.fooView.trigger("something:happened");
  expect(fooController.onSomethingHappened).toHaveBeenCalled();
});

雖然，測試失敗..

FooView should do something else when something happens.
Expected spy onSomethingHappened to have been called.
Error: Expected spy onSomethingHappened to have been called.
    at new jasmine.ExpectationResult (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:114:32)
    at null.toHaveBeenCalled (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:1235:29)
    at null.<anonymous> (http://localhost:8888/assets/foo_spec.js?body=true:225:47)
    at jasmine.Block.execute (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:1064:17)
    at jasmine.Queue.next_ (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:2096:31)
    at jasmine.Queue.start (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:2049:8)
    at jasmine.Spec.execute (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:2376:14)
    at jasmine.Queue.next_ (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:2096:31)
    at onComplete (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:2092:18)
    at jasmine.Spec.finish (http://localhost:8888/__JASMINE_ROOT__/jasmine.js:2350:5)

測試失敗是否因為事件執行時間比預期長？

Answer 1

問題是您在函數綁定到事件后監視函數。 當 jasmine 創建一個 spy 時，它將用另一個函數替換您監視的函數。

那么這里發生的是原始函數綁定到事件

this.fooView.bind("something:happened", this.onSomethingHappened, this);

之后，原始函數被 spy 替換，但這不會對您傳遞給bind函數的函數產生任何影響。

解決方案是在創建新實例之前監視FooController.prototype.onSomethingHappened ：

it("should do something else when something happens", function() {
  var onSomethingHappenedSpy = spyOn(FooController.prototype, "onSomethingHappened");
  var fooController = new FooController();
  fooController.fooView.trigger("something:happened");
  expect(onSomethingHappenedSpy).toHaveBeenCalled();
});