Is 100% code coverage a good goal?

Summary

Not usually. Coverage shows which code was executed, not whether behavior was verified; chasing 100% leads to low-value tests of trivial code. Use coverage to find untested critical paths, and set a reasonable floor or a 'no decrease' rule.

Longer Answer

Branch coverage is more informative than line coverage; mutation testing (Stryker, PIT, mutmut, Infection) measures whether tests actually detect changes.

Key Points

• Executed ≠ verified
• Find gaps in critical code
• Branch over line coverage
• Mutation testing measures test quality