Django tests are not running on a test database

After running tests where I am creating rows in the database, I noticed that the current database is used instead of a test database like I think is the default behavior of django. Unfortunately, I haven't been able to figure out how to fix this behavior.

This is currently in the settings.py

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql",
        "NAME": os.environ["POSTGRES_NAME"],
        "USER": os.environ["POSTGRES_USER"],
        "PASSWORD": os.environ["POSTGRES_PASSWORD"],
        "HOST": os.environ["POSTGRES_HOST"],
        "PORT": os.environ["POSTGRES_PORT"],
    }
}

but when adding "TEST": {"NAME": "test_database"}, it still seems to run on the main database.

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql",
        "NAME": os.environ["POSTGRES_NAME"],
        "USER": os.environ["POSTGRES_USER"],
        "PASSWORD": os.environ["POSTGRES_PASSWORD"],
        "HOST": os.environ["POSTGRES_HOST"],
        "PORT": os.environ["POSTGRES_PORT"],
        "TEST": {
            "NAME": "test_database",
        }
    }
}

How can I get it so the tests write to a fresh test database?