When adding tests for new behavior, deprecations, or environment-dependent code paths, ensure the test actually exercises the intended branch (avoid vacuous passing) and assert the concrete observable effect. Apply this checklist: 1) Force the guard conditions - If production code checks for installed modules / feature flags / config presence, your test must set up that environment. - Example pattern for module presence guards: ```python from unittest.mock import MagicMock, patch with patch.dict( sys.modules, { 'gevent': MagicMock(), # add 'eventlet' similarly if needed }, clear=False, ): worker.on_start() # assert warning/log behavior here ``` 2) Test the user-visible outcome (not just “no crash”) - For deprecations: assert the warning is emitted and the method returns/behaves as expected. - For behavioral changes: add a targeted unit test for the changed logic and update PR documentation/changelog as requested. 3) Choose the right level to avoid flakiness - If correctness depends on wall-clock/timezone transitions (DST folds, etc.), prefer deterministic unit tests that control inputs. - If you must do integration, keep it minimal and prefer existing smoke-test infrastructure over bespoke environment control. 4) Assert precisely - Tighten assertions to the expected contract (e.g., exact routing key matching) and, for logging, assert on the presence/absence of specific messages. Following these rules prevents tests that “pass vacuously,” improves regression protection for behavior changes/deprecations, and keeps higher-level tests from becoming brittle.