Few more approaches that can be mentioned as possible next steps

[bast]

• example-based vs. property-based (hypothesis library)
• snapshot based testing (syrupy library) -> helps creating regression tests
• mutation testing (mutmut): tests pass -> change a line of code (make a mutant) -> test again and check whether all mutants get "killed"

[jpthiele]

• Mocking for anything that involves needing special devices, (internet) connections, or large computations