Ember development server appears to be running in test mode

When I run ember serve while logging out the environment variable in config/environment.js, I see three values logged:

1. undefined
2. development
3. test

(This is in an inherited project.)

In a fresh app created using ember new my-app, I see three values also:

1. development
2. test
3. development

Which leads me to believe my inherited project is running in test mode and a fresh project is running in development mode as I would expect.

Running ember serve --environment=development does not change the observed behavior in the inherited project.

My questions are why do I see three values logged when running ember serve and how can I figure out why my development environment is running in test?