Allow mockCreate/mockUpdate to receive a matching function

[lorcan]

tl;dr Allow match to accept a function or attribute(s) to determine whether a create or update matched.

The function passed to match is given the requestData and can perform bespoke logic to determine whether a request matched or not. If the function returns true then a match is recorded, otherwise it is not.

We have a use-case where we're updating a complex, nested model called Parent. Parent hasMany Child relationships, each of which has multiple attributes. We're mocking an update to Parent but what we really care about is one change to an attribute of Child, let's say description. Using the existing match function we would need to pass in the entire child structure, which is quite unwieldy. By allowing match to receive a function the responsibility of determining whether a match was made belongs to the test, e.g.,:

      let done = assert.async();
      let customDescription = "special description";
      let parent = make('parent');

      let updateMock = mockUpdate(parent);
     
      updateMock.match(function(requestData) {
        return requestData.children[0].description === customDescription;
      });
      profile.set('description', customDescription);
      profile.save().then(function(parent) {
        equal(updateMock.timesCalled, 1);
        done();
      });

One thing I don't like about this approach is that the caller needs to be aware of the adaptor type and process the requestData themselves to do the match. I think it's a reasonable compromise to get the flexibility of performing arbitrary matching.

I've given a stab at writing documentation and tests for this functionality. Happy to start a discussion and rework this PR if it seems like a sensible addition.

[danielspaniel]

I guess this is not too bad an idea, and you pointed out the right flaws. But if you really need to get this down deep, there is no choice.
I can't right now think of another way to do this without the function.

And I really like / am shocked that you lay out the tests quite thoroughly and update the documentation. This almost never happens, so I just got a bruise when I fell out of my chair.

[lorcan]

Lol! Awesome! :-D
We're huge fans of ember-data-factory-guy!