Tests: pytest fails at collection (duplicate test_phase19_beta.py basename)

[nilaymallikk]

pytest errors out during collection:

ERROR tests/unit/test_phase19_beta.py
import file mismatch:
  imported module 'test_phase19_beta' -> tests/integration/test_phase19_beta.py
  wanted -> tests/unit/test_phase19_beta.py

Cause: tests/unit/test_phase19_beta.py and tests/integration/test_phase19_beta.py share a basename and the tests/ dirs have no __init__.py, plus stale __pycache__.

Fix: add __init__.py to tests/unit and tests/integration (or rename one file) and clear test caches.

Found at commit ec60ef4.