If you write Python unit tests with the built in unittest module, here’s a code snippet you can add to your TestCase classes to hide lines in tracebacks from libraries in your virtualenv and Python itself:

    def run(self, result=None):
        """Override to hide stdlib and virtualenv lines in tracebacks.

        https://docs.python.org/3.9/library/unittest.html#unittest.TestCase.run
        https://docs.python.org/3.9/library/unittest.html#unittest.TestResult
        """
        result = super().run(result=result)

        def prune(results):
            return [
                (tc, re.sub(r'\n  File ".+/(local|Python.framework|.venv)/.+\n.+\n',
                            '\n', tb))
                for tc, tb in results]

        result.errors = prune(result.errors)
        result.failures = prune(result.failures)
        return result

The local|.venv|Python.framework in the regular expression includes the common directories in my virtualenv and in Python installed by Homebrew on Mac OS X. Update with your own if necessary!

This converts test failures tracebacks like this:

Traceback (most recent call last):
  File "/opt/homebrew/Cellar/python@3.9/3.9.16/Frameworks/Python.framework/Versions/3.9/lib/python3.9/unittest/mock.py", line 1336, in patched
    return func(*newargs, **newkeywargs)
  File "/Users/ryan/src/bridgy-fed/tests/test_activitypub.py", line 1178, in test_followers_collection_unknown_user
    assert False
AssertionError

to this:

Traceback (most recent call last):
  File "/Users/ryan/src/bridgy-fed/tests/test_activitypub.py", line 1178, in test_followers_collection_unknown_user
    assert False
AssertionError