Article.findOrCreate: avoid creating duplicate articles
Prepare to have more data in feed fixture
Feed#merge (RDBMS) creates new articles
Prepare for test setup reuse
Simplify, reuse test setup
Feed.merge returns errors correctly now
Distracted by self vs bind(this)

Which, really, does not matter all that much.
Store a reference to the model's class
Feed#pull (RDBMS)

The wiring tests are a little wimpy, but should be enough