How to run tests with Pipenv

[hjacobs]

Goal: make it easier for contributors to get started.

• document how to run tests in README (only prerequisite: Pipenv)
• make py.test work from the top-level folder (do not depend on relative path, but use __file__)
• change some string paths to use pathlib.Path instead (part of stdlib since Python 3.4)

Fixes #159.

[stefan-it]

👍 for introducing pathlib :)

I think it would also be a good idea to replace the .format() constructs with f-strings? They're available with Python 3.6 (and >= 3.6 is recommended by flair) :)

[hjacobs]

@stefan-it yes, I totally agree and also told @alanakbik about both pathlib and f-strings. I just did not want to change too many things at once (even pathlib is only introduced for now where needed to make the change work).

[hjacobs]

I also propose getting rid of the TRAVIS env var to skip tests and instead have some flag to run all tests ("slow tests" or similar). The default unit tests should be self-contained and fast.

[tabergma]

👍
Thanks for the PR! I created two issues out of your suggestions:
#177
#176
Feel free to contribute to them :)