test_function fails: Error: invalid command 'pytest'

Problem

After removing the before_script for the test_function job (which builds a conda environment from environment.yml), the job fails with the above error message.

Reason

Apparently, the tests_require section in setup.cfg is only used by the test command from setuptools, which we override by using:

[aliases]
test = pytest

pytest, however, does not use the tests_require section and even if it would, I don't think it would work, because it isn't even installed at the time it is called with python setup.py test (which effectively means python setup.py pytest). pytest would need to be installed before having a chance to look at tests_require which then would tell it to install itself 😖???

See here for more info.

Solution?

For now, my only solution is to install the tests_require dependencies via the conda environment (i.e. remove the line before_script: [] again).

I would leave the tests_require section in, even though it is not used atm for documentation purposes and maybe for a future fix.