majiayu000 Test Failure Analysis Mindset
Establish a balanced investigative approach for all test failures encountered in this session.
Core Principle
Tests are specifications - they define expected behavior. When they fail, it's a critical moment requiring balanced investigation, not automatic dismissal.
Dual Hypothesis Approach
Always consider both possibilities when a test fails:
| Hypothesis A | Hypothesis B |
|---|---|
| Test expectations are incorrect | Implementation has a bug |
| Test is outdated | Test caught a regression |
| Test has wrong assumptions | Test found an edge case |
Investigation Protocol
For EVERY test failure:
1. Pause and Read
- Understand what the test is trying to verify
- Read its name, comments, and assertions carefully
- Check the test's history (git blame) for context
2. Trace the Implementation
- Follow the code path that leads to the failure
- Understand actual behavior vs. expected behavior
- Check if recent changes affected this code path
3. Consider the Context
- Is this testing a documented requirement?
- Would current behavior surprise a user?
- What would be the impact of each possible fix?
4. Make a Reasoned Decision
| Situation | Action |
|---|---|
| Implementation is wrong | Fix the bug |
| Test is wrong | Fix test AND document why |
| Unclear | Seek clarification before changing |
5. Learn from the Failure
- What can this teach about the system?
- Should additional tests cover related cases?
- Is there a pattern being missed?
Red Flags (Dangerous Patterns)
- 🚫 Immediately changing tests to match implementation
- 🚫 Assuming implementation is always correct
- 🚫 Bulk-updating tests without individual analysis
- 🚫 Removing "inconvenient" test cases
- 🚫 Adding mock/stub workarounds instead of fixing root causes
Good Practices
- ✅ Treat each test failure as a potential bug discovery
- ✅ Document analysis in comments when fixing tests
- ✅ Write clear test names that explain intent
- ✅ When changing a test, explain why the original was wrong
- ✅ Consider adding more tests when finding ambiguity
Example Responses
Good: "I see test_user_validation is failing. Let me trace through the validation logic to understand if this is catching a real bug or if the test's expectations are incorrect."
Bad: "The test is failing so I'll update it to match what the code does."
Remember
Every test failure is an opportunity to:
- Discover and fix a bug before users do
- Clarify ambiguous requirements
- Improve system understanding
- Strengthen the test suite
The goal is NOT to make tests pass quickly. The goal IS to ensure the system behaves correctly.
Related Skills
- analyze-test-failures: Detailed analysis of specific test failures
- comprehensive-test-review: Full test suite review