flake8 on tests

[jasmainak]

The flake8 linter doesn't seem to be working on the test directory. @pavanramkumar did we disable it at some point? In any case, we should fix this as soon as possible ...

[pavanramkumar]

is this simply a case of adding this line to travis.yml:

flake8 --count tests

seems to pass locally except for some docstring complaints

[jasmainak]

I think the issue is that it's not complaining when there is a pull request. Try making a pull request where you make flake8 errors in tests/ and Travis does not complain ...