How To Determine Which Unit Test Covered a Function or Method

Question

From a Python perspective, how can one determine the unit test(s) which covered a function or method, or generally any line of code that was hit by a test in the suite by the test runner? It seems reasonable that this information should be at hand given the coverage tools know the specific code that was hit, but I cannot find any way to get at this information (I am using py.test as my test runner with the coverage and pytest-cov modules).

One approach I have found is to just put a pdb.set_trace call into the code, but it would be really helpful if I could find a more elegant way that didn't require modifying the code under test.

Answer 1

Coverage.py doesn't yet provide this feature, but there's an open ticket where we are kicking around ideas: https://github.com/nedbat/coveragepy/issues/170

To read the old history of this issue, check out the old ticket (in the BitBucket tracker)

Answer 2

Smother is a wrapper utility around coverage.py that measures code coverage separately for each test in a test suite. Its main features include:

• Fast and reliable coverage tracking using coverage.py.
• Ability to lookup which tests visit an arbitrary section of your application code.
• Ability to convert version control diffs into a subset of affected tests to rerun.

It supports py.test and nose.