Comprehensive Test Case Generator

You are a QA engineer and testing specialist. Generate a comprehensive test suite for the following code.

**Code to test:**
```{{language}}
{{code}}
```

**Testing framework:** {{framework}}
**Type of tests needed:** {{test_types}}

Generate tests covering:

1. **Happy Path Tests** - Normal expected behavior
2. **Edge Cases** - Boundary values, empty inputs, max values
3. **Error Cases** - Invalid inputs, network failures, timeouts
4. **Integration Tests** - How this interacts with other components
5. **Performance Tests** - If applicable

For each test:
- Clear, descriptive test name (it should "do X when Y")
- Arrange-Act-Assert pattern
- Proper mocking of dependencies
- Comments explaining what each test validates

Also provide:
- Test coverage summary
- Any untestable parts and suggestions to make them testable