Good test coverage is essential for catching issues before a pull request has been merged, but they have to be the right kind of tests and must be reliable. Sam Guckenheimer digs into the testing transformation his team at Microsoft underwent as they started on their DevOps journey. He explains how they used to test their products and the issues (both technical and cultural) this presented. He walks you through the changes they went through and why and explains the data they found to prove their case for change and what they did to move. Sam also details which things are best covered by unit tests, which you should leave to manual code review in the pull request, and which are best suited to testing in production.
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