Add promise helpers

[tandrewnichols]

I hate stubbing promises. It would be sweet if this lib would let me do:

var spy = jasmine.createSpy('some spy');
spy.when('foo').thenResolvePromiseWith({ fruit: 'banana' });

// Then later
spy('foo').then(otherSpy)

Where the implementation is something like:

function(thing) {
  var promise = new Promise(function(resolve, reject) {
    resolve(thing);
  });
  return promise;
}

And obviously, a corresponding thenRejectPromiseWith.

[searls]

Why don't i introduce you to this thing that I actually maintain now! https://github.com/testdouble/testdouble.js

We have an issue for this: testdouble/testdouble.js#46

[tandrewnichols]

Ok, I'm interested, although I think migration from jasmine + jasmine-stealth (etc.) might be a challenging undertaking.

[searls]

td.js can work in concert with Jasmine just fine (though I'd mark which tests use Jasmine spies and which us td.js). I'd recommend just trying it on a test-by-test basis