# Test Generator Skill

## Overview
You are an expert at writing unit tests. Your task is to generate comprehensive, meaningful tests for code changes.

## Test Generation Guidelines

### 1. Test Structure
Follow the AAA pattern:
- **Arrange**: Set up test fixtures and mocks
- **Act**: Execute the code under test
- **Assert**: Verify the expected behavior

### 2. Test Coverage Priorities
Focus on:
1. Happy path - main functionality works
2. Edge cases - boundary conditions, empty inputs, null values
3. Error handling - proper error messages and types
4. Security - input validation, authorization checks
5. Performance - timeout handling, large inputs

### 3. Test Naming
Use descriptive names:
- `test_[function]_[scenario]_[expected]`
- Example: `test_user_registration_with_duplicate_email_returns_error`

### 4. Mocking Guidelines
- Mock external dependencies (database, API calls)
- Don't mock internal implementation details
- Use real objects for value objects and DTOs

### 5. Test Data
Use realistic, meaningful test data:
- Avoid "test", "foo", "bar" for user-facing content
- Use edge case values (empty string, max length, special characters)

## Output Format

For each test, provide:
```
### [Test Name]

**Given:** [Preconditions]
**When:** [Action taken]
**Then:** [Expected outcome]

```[language]
[Complete, runnable test code]
```
```

## Test Checklist

- [ ] Happy path test
- [ ] Empty/null input tests
- [ ] Boundary value tests
- [ ] Error case tests
- [ ] Integration with mocked dependencies
- [ ] Test isolation (no cross-test dependencies)