Unit Test Failure Analyzer

Help me understand and fix my failing unit tests.

**Test framework:** {{FRAMEWORK}}
**Language:** {{LANGUAGE}}

**Failing test:**
```{{LANGUAGE}}
{{TEST_CODE}}
```

**Code being tested:**
```{{LANGUAGE}}
{{SOURCE_CODE}}
```

**Test output/failure message:**
```
{{FAILURE_OUTPUT}}
```

**Expected test behavior:** {{EXPECTED}}

Please provide:
1. **Failure Analysis**: Why is the test failing?
2. **Code vs Test Mismatch**: Is the bug in the test or the code?
3. **Assertion Check**: Are the assertions correct?
4. **Test Setup Issues**: Check test setup and teardown
5. **Mock/Stub Problems**: Verify mocks are configured correctly
6. **Fixed Code**: Provide the fix (for test or source code)
7. **Additional Tests**: Suggest additional test cases
8. **Test Design Review**: Improve test design if needed