If the type is not checked then an incomprehensible error will occur later. This enforces the type and raies the same exception/msg as CPython does in that case. Docstring unmodified, just re-justified for pep8 compat.
- python/collect.py cotaining the core collection nodes - python/fixture.py containing funcargs/fixture code - python/metafunc.py generate_tests and metafunc usage - python/raises.py the pytest.raises implementation