These are the scenarios that I often find myself searching for Git commands to save me from my mistakes.

(Notes on Architecture Patterns with Python by Harry Percival, Bob Gregory: Chapter 1 - Domain Modeling)

What I Liked About This Chapter​

1. Clear definitions of value objects and entities.
2. Emphasis that not everything has to be an object: introducing the concept of a domain service function.
3. Highlighting how exceptions can express domain concepts.

Besides asserting the internal states or values in memory, we sometimes assert values impacted by external systems in a test. These can become a source of flakiness as external systems are inherently unpredictable. Examples of such assertions include: