test-generator

Test Generator Skill

Generate high-quality tests using Jest (JavaScript/TypeScript) or Pytest (Python) following established best practices.

Test Frameworks

• JavaScript/TypeScript: Jest
• Python: Pytest

Test Directory Structure

• Place tests in __tests__/ or tests/ directories
• Mirror source structure in test directories
• Use clear, descriptive test file names

JavaScript/TypeScript:

src/
  utils/
    validator.ts
__tests__/
  utils/
    validator.test.ts

Python:

src/
  utils/
    validator.py
tests/
  utils/
    test_validator.py

Test Writing Standards

Coverage Requirements

• Include at least one negative test per feature
• Test edge cases and boundary conditions
• Aim for high coverage but prioritize quality over quantity

Test Structure

Follow the Arrange-Act-Assert pattern:

// Jest example
describe('functionName', () => {
  it('should handle valid input correctly', () => {
    // Arrange
    const input = 'valid';

    // Act
    const result = functionName(input);

    // Assert
    expect(result).toBe(expected);
  });

  it('should throw error for invalid input', () => {
    // Negative test case
    expect(() => functionName(null)).toThrow();
  });
});

# Pytest example
class TestFunctionName:
    def test_valid_input(self):
        # Arrange
        input_val = 'valid'

        # Act
        result = function_name(input_val)

        # Assert
        assert result == expected

    def test_invalid_input_raises_error(self):
        # Negative test case
        with pytest.raises(ValueError):
            function_name(None)

Test Naming

• Use descriptive names that explain what's being tested
• Format: test_<what>_<condition>_<expected_result>
• Examples:
  • test_user_login_with_valid_credentials_returns_token
  • test_api_call_with_invalid_auth_raises_401

Test Quality Checklist

• Tests are independent and can run in any order
• Each test has a single, clear purpose
• Mock external dependencies (APIs, databases, file systems)
• Include both positive and negative test cases
• Test error handling and edge cases
• Use meaningful assertion messages
• Tests are fast and deterministic