sinon.js verify mock method's arguments with callback

Question

Is it possible to verify arguments with a callback. I'm thinking something like this:

var spy = sinon.spy(someObject, "method");

//json is an object with like 10 properties
spy.withArgs(function(json){
  return 'undefined' !== typeof json.importantProp1 && 'undefined' !== typeof json.importantProp2;
});

Answer 1

Not with a callback. In order to verify arguments you can use spy.calledWith and similar.

http://sinonjs.org/docs/#spies-api

Answer 2

Yes, you can do that with a matcher:

spy.calledWithMatch(function(json){
  return 'undefined' !== typeof json.importantProp1
    && 'undefined' !== typeof json.importantProp2;
});

It is also possible to create a matcher with sinon.match(function () {})) and use it with spy.withArgs .