We briefly mention negative tests in [the notes](http://github-pages.ucl.ac.uk/rsd-engineeringcourse/ch03tests/02SaskatchewanFields.html) and say that `pytest.raises` [exists](http://github-pages.ucl.ac.uk/rsd-engineeringcourse/ch03tests/03pytest.html), but we don't have a full example of a test function that uses it.
We briefly mention negative tests in the notes and say that
pytest.raisesexists, but we don't have a full example of a test function that uses it.