211: Stamp out test dependencies with pytest plugins

We want to be able to run tests in a suite, and debug them in isolation, and have the behavior be the same.  
If the behavior is different in isolation vs in a suite, it's a nightmare to debug. 

In this episode, we'll talk about:

• Causes of dependence
• Testing for dependencies using plugins
• Debugging test dependencies

Plugins discussed:

• pytest-randomly
• pytest-reverse
• pytest-random-order