Tests Pass in One Environment but Fail in Another
Tests pass locally but fail in CI, or pass in CI but fail in staging. Environment differences cause unpredictable failures.
Test Suite Problems
Symptoms related to test reliability, coverage effectiveness, speed, and environment consistency.
less than a minute
These symptoms indicate problems with your testing strategy. Unreliable or slow tests erode confidence and slow delivery. Each page describes what you are seeing and links to the anti-patterns most likely causing it.
How to use this section
Start with the symptom that matches what your team experiences. Each symptom page explains what you are seeing, identifies the most likely root causes (anti-patterns), and provides diagnostic questions to narrow down which cause applies to your situation. Follow the anti-pattern link to find concrete fix steps.
Related anti-pattern categories: Testing Anti-Patterns, Pipeline Anti-Patterns
Related guide: Testing Fundamentals
High Coverage but Tests Miss Defects
Test coverage numbers look healthy but defects still reach production.
Refactoring Breaks Tests
Internal code changes that do not alter behavior cause widespread test failures.
Test Suite Is Too Slow to Run
The test suite takes 30 minutes or more. Developers stop running it locally and push without verifying.
Tests Randomly Pass or Fail
The pipeline fails, the developer reruns it without changing anything, and it passes.