$ sudo apt install python-tox
$ cd pre-commit-hooks
$ pip install -r requirements-dev.txt
$ make test

gives the following output: https://gist.github.com/nagromc/8d44fa7c3fcddcc0af35fe5d9f789c70#file-make-test-output-txt

After some investigation, I found out my Git configuration was interfering with the tests.

I think the tests should be independent from the environment either by:

• running env HOME=/tmp make test (to change temporarily the HOME and then ignore my existing Git configuration ~/.gitconfig);
• or doing a (Python|Docker|Vagrant) trick to isolate the test environment.