Why 'Our Logic Changes Too Fast for Tests' Is a Developer Red Flag

A software developer recounts a technical interview where a CTO justified skipping automated testing by arguing that rapidly changing business logic made tests impractical. The author contends this reasoning is flawed, since frequent code changes in production actually increase risk and make test coverage more critical, not less. Without automated tests, teams must rely on manual checks and collective memory, both of which become unreliable as systems grow and staff turns over. Tests primarily serve as a safety net for modifying existing behaviour, helping developers catch unintended side effects across complex, interconnected codebases. The piece argues that fast-moving startups stand to benefit most from testing discipline, and that skipping it tends to slow down releases and raise costs over time.