I propose that we add the pytest-subtests package https://github.com/pytest-dev/pytest-subtests to our standard suite of Python packages. This allows pytest to handle unittest's subTest method correctly: running all versions even if one fails.
Without this add-on package pytest stops the test at the first failure, even if more subTest cases remain to be run. That is not a disaster, but it does mean that a test failure will not produce as much useful information as it ought to.
This seems especially apropos given Paul Price's recent work with iterator support in unit tests: https://developer.lsst.io/python/testing.html#decorators-for-iteration