coverage tools fail on relative source path

Originally reported by Dima Tisnek (Bitbucket: dimaqq, GitHub: dimaqq)

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d = coverage.data.CoverageData(".coverage")
d.lines[FILENAME] = {7: None, 8:None, 11:None, 12: None}
d.write()

then coverage reportran from . where both .coverage and source.py are present, depending on FILENAME above, observed

• source_that_doesnt_exist.py – complains that source cannot be found, ok
• /full/path/to/source.py – no error, coverage 25%, ok
• ./source.py – no error, coverage 0%, why?
• source.py – no error, coverage 0%, why?

It appears that error reporting is not consistent with coverage reporting.

same for coverage html

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• Bitbucket: https://bitbucket.org/ned/coveragepy/issue/320
• This issue had attachments: ctest.tgz. See the original issue for details.

[nedbat]

Feel free to re-open this if you can provide more information.

[manoadamro]

@nedbat I can’t even consistently reproduce it myself tbh, it just happens from time to time. Deleting all the cache files (basically everything except the actual source code files) seems fix it though. structure is:

project/
   project.py
   tests/
   setup.py
   venv/