Add public API for injection & registration

[ef4]

In an app, we encourages users to use injection over container.lookup,
and we encourage application.register over registry.register. But in our integration tests, there is no good alternative to direct this.container.lookup and this.registry.register.

So I added register and inject capability directly to the integration test context. register is fairly trivial:

    test('registering something', function(assert) {
      this.register('component:x-foo', Ember.Component.extend({
        classNames: ['i-am-x-foo']
      }));
      this.render(hbs`{{x-foo}}`);
      assert.equal(this.$('.i-am-x-foo').length, 1, 'found x-foo');
    });

inject lets you inject anything into the test context:

    test('injecting a service', function(assert) {
      this.inject.service('notifications');
      this.render(hbs`{{my-notification-viewer}}`);

      // The notifications service has been injected into our test context,
      // so we can access it here and tell it to do something.
      this.get('notifications').receivedNotification("Hello world");

      assert.equal(this.$('.notification').text(), 'Hello world');
    })

You can also give the injected thing an alternate name using as:

    test('injecting a service with aliased name', function(assert) {
      this.inject.service('notifications', { as: 'messages' });
      this.render(hbs`{{my-notification-viewer}}`);

      // The notifications service has been injected into our test context
      // as this.get('messages').
      this.get('messages').receivedNotification("Hello world");

      assert.equal(this.$('.notification').text(), 'Hello world');
    })

[rwjblue]

IMHO, these belong in the main test-module file, as they are not really related to components...

[ef4]

Good point. Will do.

[pixelhandler]

This looks nice! I've been reaching into the container and using register for a while in tests but it will be great to have a blessed path to doing so 👍

[ef4]

I moved the methods into the base test-context so they're available in all test types, and updated some tests to show that they work.