获取调用间谍的参数

Question

我正在监视 EventEmitter 中 Angular 中的方法 emit

spyOn(answerComponent.answerEmitter, 'emit');

我想检查 emit 是否使用参数 A 调用，但我不想检查与 A 的完全匹配。我想检查 emit 是否使用值 A.a, A.b 调用并忽略 A.c 的值。

有可能吗？

Answer 1

我想到了两种方法：

一个使用原生的toHaveBeenCalledWith

expect(answerComponent.answerEmitter, 'emit').toHaveBeenCalledWith(A.a);
expect(answerComponent.answerEmitter, 'emit').toHaveBeenCalledWith(A.b);
// you can think of all the callers being tracked as an array and you can assert with
// toHaveBeenCalledWith to check the array of all of the calls and see the arguments
expect(anserComponent.anserEmitter, 'emit').not.toHaveBeenCalledWith(A.c); // maybe you're looking for this as well

您还可以监视发射并调用假函数：

spyOn(answerComponent.answerEmitter, 'emit').and.callFake((arg: any) => {
  // every time emit is called, this fake function is called
  if (arg !== A.a || arg !== A.b) {
     throw 'Wrong argument passed!!'; // you can refine this call fake
  }  // but the point is that you can have a handle on the argument passed and assert it
});