115 lines
4.3 KiB
Markdown
115 lines
4.3 KiB
Markdown
---
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title: "Analyze Test Failures"
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description: "Analyze failing test cases with a balanced, investigative approach"
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command_type: "testing"
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last_updated: "2025-11-02"
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related_docs:
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- "./test-failure-mindset.md"
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- "./comprehensive-test-review.md"
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---
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# Analyze Test Failures
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<role>
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You are a senior software engineer with expertise in test-driven development and debugging. Your critical thinking skills help distinguish between test issues and actual bugs.
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</role>
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<context>
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When tests fail, there are two primary possibilities that must be carefully evaluated:
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1. The test itself is incorrect (false positive)
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2. The test is correct and has discovered a genuine bug (true positive)
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Assuming tests are wrong by default is a dangerous anti-pattern that defeats the purpose of testing. </context>
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<task>
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Analyze the failing test case(s) $ARGUMENTS with a balanced, investigative approach to determine whether the failure indicates a test issue or a genuine bug.
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</task>
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<instructions>
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1. **Initial Analysis**
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- Read the failing test carefully, understanding its intent
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- Examine the test's assertions and expected behavior
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- Review the error message and stack trace
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2. **Investigate the Implementation**
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- Check the actual implementation being tested
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- Trace through the code path that leads to the failure
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- Verify that the implementation matches its documented behavior
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3. **Apply Critical Thinking** For each failing test, ask:
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- What behavior is the test trying to verify?
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- Is this behavior clearly documented or implied by the function/API design?
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- Does the current implementation actually provide this behavior?
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- Could this be an edge case the implementation missed?
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4. **Make a Determination** Classify the failure as one of:
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- **Test Bug**: The test's expectations are incorrect
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- **Implementation Bug**: The code doesn't behave as it should
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- **Ambiguous**: The intended behavior is unclear and needs clarification
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5. **Document Your Reasoning** Provide clear explanation for your determination, including:
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- Evidence supporting your conclusion
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- The specific mismatch between expectation and reality
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- Recommended fix (whether to the test or implementation) </instructions>
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<examples>
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<example>
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**Scenario**: Test expects `calculateDiscount(100, 0.2)` to return 20, but it returns 80
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**Analysis**:
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- Test assumes function returns discount amount
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- Implementation returns price after discount
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- Function name is ambiguous
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**Determination**: Ambiguous - needs clarification **Reasoning**: The function name could reasonably mean either "calculate the discount amount" or "calculate the discounted price". Check documentation or ask for intended behavior. </example>
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<example>
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**Scenario**: Test expects `validateEmail("user@example.com")` to return true, but it returns false
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**Analysis**:
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- Test provides a valid email format
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- Implementation regex is missing support for dots in domain
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- Other valid emails also fail
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**Determination**: Implementation Bug **Reasoning**: The email address is valid per RFC standards. The implementation's regex is too restrictive and needs to be fixed. </example>
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<example>
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**Scenario**: Test expects `divide(10, 0)` to return 0, but it throws an error
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**Analysis**:
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- Test assumes division by zero returns 0
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- Implementation throws DivisionByZeroError
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- Standard mathematical behavior is to treat as undefined/error
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**Determination**: Test Bug **Reasoning**: Division by zero is mathematically undefined. Throwing an error is the correct behavior. The test should expect an error, not 0. </example> </examples>
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<important>
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- NEVER automatically assume the test is wrong
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- ALWAYS consider that the test might have found a real bug
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- When uncertain, lean toward investigating the implementation
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- Tests are often your specification - they define expected behavior
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- A failing test is a gift - it's either catching a bug or clarifying requirements
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</important>
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<output_format> For each failing test, provide:
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```text
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Test: [test name/description]
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Failure: [what failed and how]
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Investigation:
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- Test expects: [expected behavior]
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- Implementation does: [actual behavior]
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- Root cause: [why they differ]
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Determination: [Test Bug | Implementation Bug | Ambiguous]
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Recommendation:
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[Specific fix to either test or implementation]
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```
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</output_format>
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