preventing python coverage from including virtual environment site packages

Thanks to tknickman I figured it out: Use either

coverage run --source <path to project dir> test.py

or create a configuration file .coveragerc which resides in the directory you run coverage from, with the following content:

[run]
source =
    <path to project dir>

This provides you do not have your virtual environment installed under the project directory.
If you have the virtual environment installed under the project dir you can use

coverage run --source <project path> --omit <pattern> test.py

Note that omit wants a file pattern like

~/projectdir/venv/*

instead of a path.

The corresponding .coveragerc would look like this:

[run]
source=
    <path to project dir>
omit=
    <path to project dir>/<name of virtual env>/*

I still think that like packages of the standard library any packages installed under site-packages should not be covered by default.