The last beta of Coverage.py 4.1 is available: https://pypi.python.org/pypi/coverage/4.1b3 4.1 has brought big changes to how branch coverage is measured. Please try it out before I release it as 4.1! More details: http://nedbatchelder.com/blog/201605/coveragepy_41b3_and_the_truth_about_coveragepy.html Thanks, --Ned.