Testing changes REQUIRED BACKGROUND: the skill. Test craft lives in ; this skill governs which tests a change owes. Overview A test is the executable form of a claim about behavior. A change that alters behavior without touching tests is a claim nobody wrote down. Two failure modes follow: the green suite over code that could not work, and the test or gate that never ran. Tests a change owes 1. Tests change with behavior, in the same change. An empty test diff on a behavior change is a review finding, not a style preference. A pure refactor owes the opposite proof: the existing tests still pa…