Sam Hooke

These are rough notes from whatever I was working on, interested in or thinking about at the time. They vary greatly in quality and length, but prove useful to me, and hopefully to you too!

Invalid handle error from Coverage inside Tox

My tox py36 task was failing with a The handle is invalid error, and the traceback showed it was somewhere inside Coverage v4.2.2:

INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\", line 98, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\", line 133, in _main
INTERNALERROR>     config.hook.pytest_runtestloop(session=session)
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\vendored_packages\", line 745, in __call__
INTERNALERROR>     return self._hookexec(self, self._nonwrappers + self._wrappers, kwargs)
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\vendored_packages\", line 339, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\vendored_packages\", line 334, in <lambda>
INTERNALERROR>     _MultiCall(methods, kwargs, hook.spec_opts).execute()
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\vendored_packages\", line 613, in execute
INTERNALERROR>     return _wrapped_call(hook_impl.function(*args), self.execute)
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\_pytest\vendored_packages\", line 250, in _wrapped_call
INTERNALERROR>     wrap_controller.send(call_outcome)
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\pytest_cov\", line 235, in pytest_runtestloop
INTERNALERROR>     self.cov_controller.finish()
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\pytest_cov\", line 154, in finish
INTERNALERROR>     self.cov.stop()
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\coverage\", line 802, in combine
INTERNALERROR>     self.get_data()
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\coverage\", line 829, in get_data
INTERNALERROR>     self._post_save_work()
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\coverage\", line 844, in _post_save_work
INTERNALERROR>     self._warn_about_unmeasured_code(pkg)
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\coverage\", line 873, in _warn_about_unmeasured_code
INTERNALERROR>     self._warn("Module %s was never imported." % pkg, slug="module-not-imported")
INTERNALERROR>   File "c:\my_python_package\.tox\py36\lib\site-packages\coverage\", line 621, in _warn
INTERNALERROR>     sys.stderr.write(" warning: %s\n" % msg)
INTERNALERROR> OSError: [WinError 6] The handle is invalid

My tox.ini looked something like this (trimmed down for necessary context):

deps =
commands =
  pytest --cov --cov-config=.coveragerc -vv {posargs}

The problem turned out to be that in my .coveragerc file, I had misspelt the name of my Python package:

source =

source =
parallel = true

Correcting my_python_packge to my_python_package in .coveragerc stopped Coverage from raising the “Module %s was never imported” warning, which stopped the invalid handle error.

<< Previous: Run Django makemigrations as tox task
Next: Bootstrapping pip >>