Python Knowledge Share: Introduction to testing with pytest

An hour long Python Knowledge Share session on "Intro to testing with pytest" delivered to Gigaclear QA and devs on May 2nd 2024.

The example code includes a connexion 3 - Flask 3 web app we'll be testing (with Pipfile for pipenv), and eight tests files of examples we'll work through.

This knowledge share is an introduction to testing with pytest including some principles of automated testing.

Topics covered include:

* virtual environments and pipenv (installing pytest)
* pytest command line for collecting and running tests
* Simple test functions and asserts
* Testing exceptions
* Test parameterisation for test combinations
* Test marking for running test subsets
* Principles of testing (unit tests versus end to end testing, building test helpers etc)
* mocking and patching