consider using `tox` for testing

[vlcinsky]

Currently testing is supported by:

• travis
• Makefile

Anyway, running local tests for multiple python versions is either impossible or very difficult as one would have to arrange local Travis test.

My proposal is:

• add tox based testing: this will allow running all the tests locally without much difficulties
• consider modification of travis.yml to reuse the tox.ini. This is not strictly required, but it would simplify updating the test suite.

Personally I like tox a lot and at the same time I really enjoy pipenv. One area, where I am in doubt searching for obvious way to do things is testing multiple python interpreters when pipenv is in place with it's Pipfile and possibly Pipfile.lock

So far I use tox.ini from which I refer to required package via requirements.txt.

Anyway, whatever way of installing dependencies will be used with tox.ini, I believe it would simplify multiple interpreter test significantly.

[timofurrer]

add tox based testing: this will allow running all the tests locally without much difficulties

I've just added a tox.ini in 00a0ceb.

consider modification of travis.yml to reuse the tox.ini. This is not strictly required, but it would simplify updating the test suite.

I'd rather use pipenv as common tool for tox and travis. I think we leave it as it is right now.

Thanks for the suggestion 🎉

[vlcinsky]

@timofurrer well done.

I run tox and all works well on my machine (py2.7, py3.5, py3.6 - py3.4 is missing here, that is my setup). All tests passed, second run runs relatively fast, now I feel more comfortable.

Thanks.