Welcome!
There are three ways the Park unit test suite is run.
As a developer, use python setup.py test. This runs the suite in
the current development directory and does not require a virtualenv to
be set up.
As a contributor, your Github pull requests will be tested on Travis CI. The configuration for that is in .travis.yml. This runs the test suite on all supported platforms, which are enumerated in that file.
As a release maintainer, install tox (in a virtualenv is fine)
and run it in the top level Park source directory. This will build a
source distribution, install that into a virtualenv for each supported
platform, and run the test suite in each.