Basically, make the existing unit test suite is importable so that downstream client tool can reuse base test case to setup environment for writing their own tests.

For example, testing a subcommand, a fake repository and a cloned from that base repository are required. Code to initialize those two repositories are reusable. So, rpkg2 could have a base class, it should be also reusable for downstream client like this

import rpkg2.tests import BaseTestCase
class TestContainerBuild(BaseTestCase):
    pass