Play with tox and setup a small tox.ini

Signed-off-by: Bert van Hall <bert.vanhall@gmx.de>

Author: The-42

tox.ini

@@ -0,0 +1,16 @@
+# tox (https://tox.readthedocs.io/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+
+[tox]
+envlist = py35, py36, py37, py38, py39, pypy2.7, pypy3.5, pypy3.6
+skip_missing_interpreters = True
+tox_pyenv_fallback = False
+
+[testenv]
+deps =
+    setuptools >= 45
+
+commands =
+    python setup.py test