I guess it's worth taking a look at some more complex open source Python projects. I think pandas [1] is a pretty good example, with a relatively large amount of Python and Cython code.
They start off with a pretty decent amount of unit tests (84% coverage) and make sure it's visible to developers using:
- Travis [2] (has to pass on pull requests too before contributions are accepted)
- Coverage [3]
There's also Code Climate [4] for some more introspection.
[1]: https://github.com/pydata/pandas
[3]: https://codecov.io/