A few years ago, I had a problem that many Python team leads eventually face. I was working at an AI automotive startup in Berlin. The company was later acquired by Valeo , the French global automotive supplier, and is now part of Seeing Machines . At that time, we had just started adopting clean code practices and SOLID principles seriously. I was a team lead, and my challenge was to educate 15 Python developers to start testing and bring a huge legacy codebase under test coverage . We started weekly shared learning sessions. Each week, I prepared one chapter from Python Testing with pytest, Second Edition by Brian Okken and turned it into a talk with examples from our own codebase. That worked. Developers understood pytest better when they saw it applied to code they touched every day. But the book alone was not enough for our situation. We still needed to add practical CI/CD with GitHub Actions, more real-world examples, testing pyramid discussions, and TDD/BDD concepts.…