TypeError: 'x' is not a function

[danruziska]

Hi,

I'm trying to stub a function, returning a fake value and comparing Sinon and Testdouble implementations. So, for the former, I'm using this command:

sinon.stub(catHelper,'getCategoryByPath').callsFake(function(){
  let result = {
	id:1
  };
  return result;
});

It works fine, Sinon can recognize the getCategoryByPath function inside the catHelper object.
I tried to achieve the same result using TestDouble, so I did the same logic:

let catHelperMock = testdouble.replace(catHelper,'getCategoryByPath');    
testdouble.when(catHelperMock.getCategoryByPath('path','')).thenReturn(
{
  id:1
});  

But I'm getting the following error:

TypeError: catHelperMock.getCategoryByPath is not a function

For some reason, it's not recognizing the funciotn. Is there an alternative to achieve the same result?

Thanks!

[searls]

Does catHelperMock.getCategoryByPath actually exist? This example works fine:

https://runkit.com/searls/59011302acedf10011cc8666