coveragepy coverage of trace functions

[nedbat]

Originally reported by Loic Dachary (Bitbucket: dachary, GitHub: dachary)

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The code in tracer.c, pytracer.py, or code in control.py called from those does not show as covered when running make metacov. Using mocks would be tedious and error prone.

The code could run with a trace function that captures the sequence of events, and frames. Then replay those against the code. The problem is, you can't just capture the events, you have to actually send them to the real trace function also, and if that function has state, like whether a file has been should_trace'd already or not, then it's hard to replay the events.

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• Bitbucket: https://bitbucket.org/ned/coveragepy/issue/547