Run test suite with Python dev mode & warnings throwing errors

Author: thibaudcolas

tox.ini

@@ -8,7 +8,7 @@ whitelist_externals =
 install_command =
     ./tox_install.sh {packages}
 commands =
-    poetry run ./runtests.py
+    poetry run python -X dev -W error runtests.py
     poetry run django-admin render_patterns --settings=tests.settings.dev --pythonpath=. --dry-run
 deps =
     dj22: Django>=2.2,<2.3