Unit Testing Patterns

Comprehensive patterns for writing effective, maintainable unit tests following TDD principles.

Test-Driven Development (TDD)

The TDD Cycle

1. Red - Write a failing test first
2. Green - Write minimal code to pass the test
3. Refactor - Improve code while keeping tests green

// Step 1: RED - Write failing test
describe('Calculator', () => {
  it('should add two numbers', () => {
    const calc = new Calculator();
    expect(calc.add(2, 3)).toBe(5);
  });