Test Failure Mindset

---
name: test-failure-mindset
description: Establishes a dual-hypothesis investigation mindset for every test failure — treating failures as diagnostic signals that may indicate a real bug OR an incorrect test, never defaulting to automatic code changes or test dismissal. Use when encountering failing tests, debugging test errors, running a test suite that shows regressions, or any request involving "test failure analysis", "why is this test failing", or "should I fix the test or the code". Loads a 5-step protocol covering failure reading, implementation tracing, requirement context, reasoned decision-making, and learning extraction. Works alongside analyze-test-failures for detailed per-failure analysis and comprehensive-test-review for full suite review.
user-invocable: true
---

# Test Failure Analysis Mindset

Establish a balanced investigative approach for all test failures encountered in this session.

## Core Principle

Load and follow the standards in `/python-engineering:standards-for-python-development` when shared testing or quality rules from this plugin apply.

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| Test is outdated                | Test caught a regression |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**: Use `/python-engineering:analyze-test-failures` for detailed analysis of specific test failures
- **comprehensive-test-review**: Use `/python-engineering:comprehensive-test-review` for full test suite review