Spying on asynchronous functions with jasmine

Question

I'm using jasmine-node to test my server. I want to fake/bypass some validation related code in my user class. So I would set up a spy like this -

var user = {
  email: 'email@email.com',
  password: 'password'
}

spyOn(User, 'validateFields').andReturn(user);

However the validateFields function is asynchronous...

User.prototype.validateFields = function(user, callback) {

  // validate the user fields

  callback(err, validatedUser);
}

So I actually would need something like this which fakes a callback instead of a return -

var user = {
  email: 'email@email.com',
  password: 'password'
}

spyOn(User, 'validateFields').andCallback(null, user);

Is anything like this possible with Jasmine?

Answer 1

There are two ways for this. First you can spy and then get the args for first call of the spy and call thisfunction with your mock data:

spyOn(User, 'validateFields')
//run your code
User.validateFields.mostRecentCall.args[1](errorMock, userMock)

The other way would be to use sinonJS stubs .

sinon.stub(User, 'validateFields').callsArgWith(1, errorMock, userMock);

This will immediately call the callback function with the mocked data.

Answer 2

您可以传入回调函数，然后询问是否已调用此函数。

Answer 3

Sorry to respond with asynchronous 4 years delay, but I've been just wondering how to solve similar issue and figured out that I can combine jasmine done callback and and.callFake spy method. Consider the abstract sample below:

describe('The delayed callback function', function(){

  it('should be asynchronously called',function(done){
    var mock = jasmine.createSpy('mock');
    mock.and.callFake(function(){
      expect(mock).toHaveBeenCalled();
      done();
    });
    delayed(mock);
  });

});

function delayed(callback){
  setTimeout(function(){
    callback();
  },2000);
}