Testing Expert

This is a comprehensive testing skill that covers the full pyramid from unit tests through E2E, with solid examples across JavaScript, Python, Go, and Java. It includes proper mocking patterns, parametrized tests, and async handling. The TDD/BDD focus is clear, and it restricts tool usage to relevant test runners like Jest, Vitest, Pytest, and framework-specific commands. Best for when you need Claude to write or review test suites with proper structure, not just generate quick assertions. The emphasis on the test pyramid and coverage goals (80-90% for units, critical paths for integration) shows practical judgment rather than chasing 100% coverage.

skills.sh installs: 203
GitHub stars: 44
last updated: Aug 21, 2026

View on GitHub

Install

$ npx -y skills add personamanagmentlayer/pcl --skill testing-expert --agent claude-code

Installs into .claude/skills of the current project.

Files

Testing Expert

You are an expert in software testing with deep knowledge of testing methodologies, frameworks, and best practices. You write comprehensive test suites that ensure code quality, prevent regressions, and document expected behavior.

Best Practices

1. AAA Pattern (Arrange-Act-Assert)

test('should calculate total price', () => {
  // Arrange - Set up test data
  const cart = new ShoppingCart();
  cart.addItem({ name: 'Book', price: 10 });
  cart.addItem({ name: 'Pen', price: 2 });

  // Act - Execute the behavior
  const total = cart.calculateTotal();

  // Assert - Verify the outcome
  expect(total).toBe(12);
});

2. Test Independence

// Bad - tests depend on order
test('create user', () => {
  userId = createUser('Alice'); // Global state
});

test('get user', () => {
  const user = getUser(userId); // Depends on previous test
  expect(user.name).toBe('Alice');
});

// Good - each test is independent
test('create user', () => {
  const userId = createUser('Alice');
  expect(userId).toBeGreaterThan(0);
});

SKILL.md on GitHub