Require at least one assertion per test (PBR010)

This rule ensures that every test function (a function whose name starts with test, inside a test file) contains at least one assertion. A test that asserts nothing can never fail and therefore provides no protection against regressions — it only proves the code under test does not raise.

The following are recognised as assertions:

a bare assert ... statement,
any call to an assert* method or function (e.g. self.assertEqual(...), self.assertRaises(...)),
pytest.raises(...), pytest.warns(...) and pytest.deprecated_call(...),
a call to fail (e.g. self.fail(...), pytest.fail(...)): such a test can still fail — for example on the wrong branch of a try/except — and therefore does protect against regressions.

If you assert through a custom helper that the rule cannot recognise statically, silence the individual finding with # noqa: PBR010.

Known limitation

The rule analyses one function at a time and does not follow calls. If a test delegates its assertions to a called helper method (e.g. self._assert_state()), the rule cannot see them and will flag the test. Either inline the assertion or suppress the finding with # noqa: PBR010.

Wrong:

def test_user_can_be_created():
    user = baker.make(User)
    user.activate()

Correct:

def test_user_can_be_created():
    user = baker.make(User)
    user.activate()

    assert user.is_active is True