[Django]-Django doesn't create test database when running test

Using django.test.TestCase instead of unittest.TestCase helps according to the document
https://docs.djangoproject.com/en/3.1/topics/testing/overview/

If your tests rely on database access such as creating or querying models, be sure to create your test classes as subclasses of django.test.TestCase rather than unittest.TestCase.

Using unittest.TestCase avoids the cost of running each test in a transaction and flushing the database, but if your tests interact with the database their behavior will vary based on the order that the test runner executes them. This can lead to unit tests that pass when run in isolation but fail when run in a suite.