Test Generator Skill

Purpose

This skill provides comprehensive test scaffolding and templates for quickly setting up unit and integration tests with proper structure, fixtures, and mocking configurations. It guides the creation of well-structured, maintainable tests following best practices.

Activation

On-demand via command: /generate-tests <file-path>

Example:

/generate-tests src/tools/example/core.py

When to Use

• Starting tests for a new module
• Need test structure quickly
• Adding tests to existing code
• Setting up test fixtures and mocks
• Creating integration test scaffolding
• Following pytest or Jest best practices

Resources

testing-templates/unit-test.py

Complete pytest unit test template with:

• Proper import structure
• Fixture definitions (sample data, temp files, mocks)
• Test function templates (Arrange-Act-Assert pattern)
• Test class templates
• Parametrize examples
• Mock/patch configurations
• Common assertion patterns

testing-templates/integration-test.py

Complete integration test template with:

• Service integration patterns
• Database integration examples
• File system test patterns
• End-to-end workflow examples
• Cleanup patterns (tmp_path, fixtures)
• Real dependency testing (not mocked)

Provides

Test File Scaffolding

• Proper file structure and organization
• Naming conventions (test_*.py or *_test.py)
• Import statements
• Test class/function structure

Fixture Setup

• pytest: Sample fixtures for common use cases
• Jest: Mock implementations and spy configurations
• Reusable test data fixtures
• Setup/teardown patterns

Mock Configurations

• unittest.mock: Mock and patch examples
• pytest-mock: pytest-specific mocking
• Jest: Mock modules and functions
• Spy and stub patterns

Coverage Analysis Helpers

• Test organization for better coverage
• Edge case identification
• Boundary testing patterns

Usage Examples

Example 1: Generate Unit Tests for Module

/generate-tests src/tools/doc_fetcher/core.py

Provides:

• tests/test_doc_fetcher_core.py structure
• Fixtures for test data
• Test cases for each public function
• Mock configurations for external dependencies

Example 2: Generate Integration Tests for API

/generate-tests src/api/endpoints.py

Provides:

• tests/integration/test_endpoints.py structure
• API client fixtures
• Request/response test patterns
• End-to-end workflow tests

Example 3: TypeScript/Jest Tests

/generate-tests src/components/Button.tsx

Provides:

• src/components/Button.test.tsx structure
• Jest mock configurations
• Component testing patterns
• Snapshot testing examples

Test Structure Patterns

Arrange-Act-Assert (AAA) Pattern

def test_function_name_condition_expected():
    """Test description."""
    # Arrange - Set up test data and conditions
    input_data = {"key": "value"}
    expected = "result"

    # Act - Execute the function under test
    result = function_under_test(input_data)

    # Assert - Verify the outcome
    assert result == expected

Test Class Organization

class TestClassName:
    """Tests for ClassName."""

    @pytest.fixture
    def instance(self):
        """Create test instance."""
        return ClassName()

    def test_method_success(self, instance):
        """Test successful method execution."""
        result = instance.method()
        assert result is not None

    def test_method_error_handling(self, instance):
        """Test method handles errors."""
        with pytest.raises(ValueError):
            instance.method(invalid_input)

Parametrized Tests

@pytest.mark.parametrize("input,expected", [
    ("test1", "result1"),
    ("test2", "result2"),
    ("test3", "result3"),
])
def test_function_with_parameters(input, expected):
    """Test function with multiple inputs."""
    result = function_under_test(input)
    assert result == expected

Mocking Patterns

Mock External Dependencies

from unittest.mock import Mock, patch

@patch('module.external_service')
def test_with_mocked_service(mock_service):
    """Test with mocked external service."""
    # Configure mock
    mock_service.return_value = "mocked_response"

    # Test function that uses service
    result = function_that_calls_service()

    # Verify
    assert result == "expected"
    mock_service.assert_called_once()

Fixture-Based Mocks

@pytest.fixture
def mock_database():
    """Mock database connection."""
    db = Mock()
    db.query.return_value = [{"id": 1, "name": "test"}]
    return db

def test_database_query(mock_database):
    """Test database query."""
    result = get_data(mock_database)
    assert len(result) == 1
    mock_database.query.assert_called()

Integration Test Patterns

API Integration Testing

def test_api_endpoint_integration(client):
    """Test API endpoint with real client."""
    # Arrange
    payload = {"data": "test"}

    # Act
    response = client.post("/api/endpoint", json=payload)

    # Assert
    assert response.status_code == 200
    assert response.json()["status"] == "success"

Database Integration Testing

def test_database_integration(db_session):
    """Test database operations."""
    # Arrange
    record = Model(name="test", value=123)

    # Act
    db_session.add(record)
    db_session.commit()

    # Assert
    result = db_session.query(Model).filter_by(name="test").first()
    assert result is not None
    assert result.value == 123

Coverage Considerations

Testing Requirements

• Aim for 80%+ test coverage
• Test all public functions and methods
• Test edge cases and boundary conditions
• Test error handling paths
• Test integration points

Coverage Tools

# Python with pytest-cov
pytest --cov=src --cov-report=html

# JavaScript with Jest
jest --coverage

# View coverage report
open htmlcov/index.html  # Python
open coverage/lcov-report/index.html  # JavaScript

Best Practices

Test Naming

• Use descriptive names: test_function_condition_expected
• Example: test_process_data_invalid_input_raises_error

Test Organization

• One test file per source file
• Group related tests in classes
• Use fixtures for common setup

Test Independence

• Tests should not depend on each other
• Each test should set up its own data
• Clean up resources after tests

Test Readability

• Clear test descriptions
• Simple, focused test cases
• Readable assertions

Mock Judiciously

• Mock external dependencies
• Test real code paths when possible
• Verify mock interactions

Notes

• Guidance Only: This skill provides templates and guidance. It does not automatically generate test files.
• Language Support: Primary support for Python (pytest) and TypeScript/JavaScript (Jest).
• Customization: Templates should be adapted to specific project needs.
• Best Practices: Follow project-specific testing conventions and standards.

Used When

• Starting test implementation for a new module
• Need quick test structure setup
• Learning test patterns for the project
• Ensuring consistent test organization
• Setting up complex fixtures or mocks
• Creating integration test scaffolding