At the moment the images don't bundle a browser which means we can't use it to run the tests in CI. As an alternative we use the danlynn/ember-cli images, but they don't always match the versions of madnificent/ember.

For example madnificent/ember 3.28.5 uses npm v8.3 while danlynn/ember-cli 3.28.5 uses npm v8.1.2 (which doesn't support the overrides feature).

Ideally we can use the image that we use for builds (and local development) while running the tests. Ember apps are configured to run tests in Chrome by default, but we can change the testem configuration to use any browser we want.