Use coverage instead of pytest-cov,

and tell coverage to don't include __init__.py

.coveragerc

 [run]
-omit = tests/*
-       *__init__*
+omit = */__init__.py

tox.ini

@@ -31,7 +31,8 @@ commands=
 # passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
 deps = .[test]
 commands =
-   py.test -svx --cov --cov-report=
+   coverage run --rcfile={toxinidir}/.coveragerc --source=sbws -m pytest -svx {toxinidir}/tests
+
 
 [testenv:doc]
 deps = .[doc]