Is there a way to use the FixtureAdapter for tests only?

Testing
1

How can I make ember user the FixtureAdapter when running tests?

I thought the code below would do it, but it doesn’t, api calls are still being made.

Is this doable?

tests/helpers/start-app.js

Ember.run(function(){
  App = Application.create(attributes);
  App.setupForTesting();
  App.injectTestHelpers();

  // .create doesn't work either
  App.ApplicationAdapter = DS.FixtureAdapter.extend({...});
});