CI exercise fails

[dsmits]

CI exercise fails because pytest cannot find any tests.

This is because the default github workflow runs pytest without any arguments. By default, pytest searches for files that start with test_. It won't find any because we have only asked the participants to create a file called example.py.

Either instruct the participants to create just a file test_example.py, or ask the participants to create two files (example.py and test_example.py).
The latter option requires the participants to import the add function into test_example.py, which can give some issues, so easiest it would be to just rename the original file.