Test Generation with Edge Cases

Generate tests for this {{language}} code using {{test_framework}}:

```
{{paste your code}}
```

Requirements:
- Cover the happy path with realistic data
- Test edge cases: empty input, null/undefined, boundary values, very large input
- Test error paths: invalid input, network failures, permission errors
- Use descriptive test names that explain the expected behavior: "should return empty array when user has no orders"
- Arrange-Act-Assert pattern
- No mocks unless the dependency is external (database, API, filesystem)

For each test, add a brief comment explaining WHY this case matters — what bug would it catch?