python test_gilded_rose.py
For e.g. 10 days:
python texttest_fixture.py 10
You should make sure the command shown above works when you execute it in a terminal before trying to use TextTest (see below).
There are instructions in the TextTest Readme for setting up TextTest. You will need to specify the Python executable and interpreter in config.gr. Uncomment these lines:
executable:${TEXTTEST_HOME}/python/texttest_fixture.py
interpreter:python