Expose test helpers for component unit tests

[cbrock]

In ember-cli, test helpers are made available for integration tests by calling startApp(). Ember test helpers are not available for unit tests, nor is it appropriate to call startApp() within a unit test.

However, because unit tests for Ember components rely on the component being tested to exist as part of the DOM, a subset of test helper methods are actually useful in that context - for example, fillIn() or find() (conversely, other test helpers like visit() still do not make sense in the context of a component unit test).

It would be useful to expose an appropriate subset of DOM-related test helpers, scoped to the component being tested (e.g. this.fillIn('selector', 'value'), since the component being tested exists as part of the DOM.

[jeremywrowe]

I hate bumping issues because I realize everyone is really busy. But I think this still makes a lot of sense; especially with the recently added { integration: true } for components. I've done some looking around but haven't rolled over the correct rock yet. If I could be pointed in the right direction, i'd be happy to open a pull request. (if it is feasible)

[spinlock99]

I'm having a similar issue where I have a custom helper that I'd like to expose in my unit tests. It would be very helpful to not have to register it in every file.

[rwjblue]

The easiest way to get these helpers immediately is by using the ember-native-dom-helpers addon. In a future iteration (after another testing RFC) ember-test-helpers will provide them directly...