test coverage doesn't report any data

[Markus Zoeller (markus_z)]

Description
===========
We cannot create a test coverage report with the tox test env "cover"

Steps to reproduce
==================
    $ git clone https://github.com/openstack/nova-dpm
    $ cd nova-dpm
    $ tox -e cover

Expected result
===============
A test coverage report gets created.

Actual result
=============
No coverage report, but warnings instead:
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Ran 10 tests in 9.215s (-0.482s)
    PASSED (id=9)
    No data to report.

Environment
===========
$ git log --oneline -1
6f87677 Instance Destroy,poweron,poweroff,reboot

Logs & Configs
==============

    $ tox -e cover
    cover installed: [...]
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Coverage.py warning: Module nova-dpm was never imported.
    Coverage.py warning: No data was collected.
    Ran 10 tests in 9.215s (-0.482s)
    PASSED (id=9)
    No data to report.

[Markus Zoeller (markus_z) (mzoeller)]

It has to be something with the paths in the tox configuration ("tox.ini") or coverage configuration (".coverage.rc"). I can do this to create results:

    $ git clone https://github.com/openstack/nova-dpm
    $ cd nova-dpm
    $ tox -e cover
    $ source .tox/cover/bin/activate
    $ (cover) coverage run --source=nova_dpm -m unittest discover -s nova_dpm/tests/
    $ (cover) coverage report

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/420208

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/420208
Committed: https://git.openstack.org/cgit/openstack/nova-dpm/commit/?id=ce0676d3d8e2ffa3b473884fa6db19df1e4bbc0a
Submitter: Jenkins
Branch: master

commit ce0676d3d8e2ffa3b473884fa6db19df1e4bbc0a
Author: Tin Lam <email address hidden>
Date: Fri Jan 13 15:54:07 2017 -0600

    Fix an issue where no test coverage report is created

    Running `tox -ecover` does not generate the coverage report.
    Instead the following is displayed to the user:

        No coverage report, but warnings instead:
        Coverage.py warning: Module nova-dpm was never imported.

    This patch set fixes the problem.

    Change-Id: Iec85cf3a6453da3630d49df29c69b55ca5075d17
    Closes-Bug: #1655920