Jasmine spies callThrough and callFake

Question

I have a scenario whereby I want to call done() on a beforeEach after a callback has been invoked.

I tried to do this as follows :

spyOn(scope, 'onAdmin').and.callThrough().and.callFake(function(){done()})

But I'm not sure I get the right behaviour. Essentially what I want to achieve is to be able to call done() after each callback is done doing what it does.

UPDATE: workaround solution

scope.onAdminBackup = scope.onAdmin;
spyOn(scope, 'onAdmin').and.callFake(function(admin)  {

 scope.onAdminBackup();
 done() ;

})  

Answer 1

I found a work around way to do this. Jasmine has a method called addSpyStategy where you can add a custom strategy like callThrough or callFake. It would look something like this:

jasmine.addSpyStrategy('callThroughAndThen', (spy, fn) => {
  return function() {
    spy.and.callThrough();
    setTimeout(() => fn(...arguments), 0);
  }
});

the timeout makes sure the real function finishes before executing the custom function. Then for your spy, you can do this:

const spy = spyOn(scope, 'onAdmin')
 spy.and.callThroughAndThen(spy, () => {
  // your custom callback
  done();
});

note: make sure to put custom strategy in a beforeEach block

Answer 2

I have never chained these kinds of functions together cuz in my mind they seem to do the opposite. You are saying when I call this method -onAdmin - in the scope call it as normal. Which is what the callThrough method jasmine provides for us does.

But then you are chaining along a callFake method as well so then you say but dont actually call it call this fake function instead - very conflicting.

If you want to call spy on the method onAdmin and instead of it being fired you want it to do something else - something mocked - then use the .and.callFake(fn). Also take into account like @stefan above said - dont invoke the function - callFake is simply wanting a function as a parameter it will take care of calling it itself.

This might be more along the lines of what you are looking for, if not show us some more code.

spyOn(scope, 'onAdmin')and.callFake(done)

Answer 3

you are calling done right-away when you write done() try passing in done as a value:

spyOn(scope, 'onAdmin').and.callThrough().and.callFake(done)