Django-nose cannot find tests in folders

Question

I know there are similar questions on StackOverflow, but I can't quite find one that matches my situation.

I'm working on an app built by someone else and have been adding tests.

The folder structure is like so:

my_project
├── apps
│   ├── app1
|       ├── __init__.py
│       ├── tests.py
│   └── app2
│   └── app3
├── settings.py
├── urls.py
└── views.py

However, when I run python manage.py test, I get 0 tests run. Running the individual apps (python manage.py test app1) works when django-nose isn't installed, but works without django-nose.