edx-sphinx-theme has an assortment of test cases and code quality checks to catch potential problems during development. To run them all in the version of Python you chose for your virtualenv:

$ make validate

To run just the unit tests:

$ make test

To run just the code quality checks:

$ make quality

To run the unit tests under every supported Python version and the code quality checks:

$ make test-all

To generate and open an HTML report of how much of the code is covered by test cases:

$ make coverage