Testing in Python is disabled by default. To enable testing, use the Python: Configure Tests command on the Command Palette.
Start testing in VS Code by using Python: Configure Tests (it automatically chooses one testing framework and disables the rest).
Otherwise, you can configure tests manually by setting only one of the following to True:
python.testing.unittestEnabledpython.testing.pytestEnabledpython.testing.nosetestsEnabled