.coveragerc

[run]
branch = True
parallel = True
concurrency = multiprocessing,thread
source_pkgs = demo

readme.txt

graingert@conscientious  venv  ~/projects/coverage_multiprocess_chdir  coverage run demo.py
 graingert@conscientious  venv  ~/projects/coverage_multiprocess_chdir  coverage combine    
Combined data file .coverage.conscientious.481389.XMZfknLx
Combined data file .coverage.conscientious.481390.XhvFJIXx
 graingert@conscientious  venv  ~/projects/coverage_multiprocess_chdir  coverage report -m  
Name      Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------
demo.py      19      1      6      1    92%   10, 23->exit
-----------------------------------------------------
TOTAL        19      1      6      1    92%

demo.py

import sys
import multiprocessing
import tempfile
import contextlib

def hit():
    pass

def missed():
    pass

def go(target):
    p = multiprocessing.Process(target=target)
    p.start()
    p.join()

def main():
    go(hit)
    with tempfile.TemporaryDirectory() as tmp:
        with contextlib.chdir(tmp):
            go(missed)

if __name__ == "__main__":
    sys.exit(main())