docs explaing pytest for Python and C++ code

docs/source/index.rst

@@ -41,6 +41,7 @@ Contents
 
    usage/getstart
    usage/ourdocs
+   usage/ourtests
    src_py/index
    src_cxx/index
 

docs/source/usage/ourtests.rst

@@ -0,0 +1,36 @@
+Our Tests
+=========
+
+This project uses pytest for executing the Python tests in the `./tests` directory. These tests are
+included in the CI.yml and can be used to test both Python and C++ code.
+
+.. _python-test:
+
+Testing Python Code
+################### 
+
+Easily done with pytest!
+
+Simply import the code you want to test (e.g. module, function, class etc.)
+within a script called ``./tests/test_[name].py`` with a "name" of your choosing in the `./tests`
+directory.
+
+Then run pytest on the entire tests directory or on your test. For example, ``pytest ./tests`` would test
+every test in the `./tests` directory, whereas ``pytest test_[name].py`` runs just your test.
+
+Testing C++ Code
+################
+
+For testing C++ code, we first make a Python module out of it using pybind11, e.g. via
+
+.. code-block:: console
+  
+  $ cmake -S ./ -B ./build
+  $ cd build && make
+
+which fetches and uses pybind11 (see CMakeLists.txt) to make a Python module out of the C++ code - 
+provided you have first written appropriate bindings(!). The Python module is then tested using
+pytest just :ref:`like an ordinary python module <python-test>`.
+
+You can find out more about pybind11 by visiting
+`their repository <https://github.com/pybind/pybind11/>`_