Add information on how to run unit tests to documentation

Author: locsmith

README.rst

@@ -25,3 +25,12 @@ is to read the documentation at `read the docs <https://pynmrstar.readthedocs.or
 
 .. |Wheel| image:: https://img.shields.io/pypi/wheel/pynmrstar.svg
    :target: https://pypi.org/project/PyNMRSTAR
+
+
+Running the unit tests
+----------------------
+
+.. role:: bash(code)
+   :language: bash
+
+if you with to run the unit tests distributed with PyNMR-Star, please see the readme in :bash:`pynmrstar/unit_tests`

pynmrstar/unit_tests/README.rst

@@ -0,0 +1,38 @@
+
+How to run the unit tests
+=========================
+
+
+Setup
+-----
+
+All the following commands should be made from a shell inside the
+PyNMRStar distribution folder (PyNMRStar not PyNMRStar/pynmrstar).
+
+Some parts of the unit test structure are in a sub-repo that needs to be
+downloaded separately using git.
+
+.. code:: bash
+
+   git submodule init
+   git submodule update
+
+if you have downloaded PyNMR-Star as a git hub repo you may need
+
+.. code:: shell
+
+   export PYTHONPATH=<full-path-to-PyNMRStar-folder>
+
+Using unit test
+---------------
+
+.. code:: bash
+
+   python3 pynmrstar/unit_tests/test_pynmrstar.py
+
+Using pytest
+------------
+
+.. code:: bash
+
+   pytest pynmrstar/unit_tests