Tdd Workflow

Test-Driven Development Workflow

This skill ensures all code development follows TDD principles with comprehensive test coverage in Antigravity projects.

When to Activate

• Writing new features or functionality
• Fixing bugs or issues
• Refactoring existing code
• Adding API endpoints
• Creating new components

Core Principles

1. Tests BEFORE Code - Always write tests first
2. 80%+ Coverage - Unit + integration + E2E
3. All edge cases covered - Null, empty, boundary, error scenarios

TDD Workflow Steps

Step 1: Write User Journeys

As a [role], I want to [action], so that [benefit]

Step 2: Generate Test Cases

describe('Feature', () => {
  it('returns expected result for valid input', async () => { /* ... */ })
  it('handles empty input gracefully', async () => { /* ... */ })
  it('falls back correctly when dependency unavailable', async () => { /* ... */ })
  it('sorts results correctly', async () => { /* ... */ })
})

Step 3: Run Tests (They Should Fail)

npm test
# Tests should fail - implementation doesn't exist yet

Step 4: Implement Minimal Code

Write just enough to make tests pass.

Step 5: Run Tests Again

npm test
# Tests should now pass

Step 6: Refactor

Improve code quality while keeping tests green.

Step 7: Verify Coverage

npm run test:coverage
# Verify 80%+ coverage achieved

Testing Patterns

Unit Test Pattern (Jest/Vitest)

import { render, screen, fireEvent } from '@testing-library/react'
import { Button } from './Button'

describe('Button Component', () => {
  it('renders with correct text', () => {
    render(<Button>Click me</Button>)
    expect(screen.getByText('Click me')).toBeInTheDocument()
  })

  it('calls onClick when clicked', () => {
    const handleClick = jest.fn()
    render(<Button
    fireEvent.click(screen.getByRole('button'))
    expect(handleClick).toHaveBeenCalledTimes(1)
  })

  it('is disabled when disabled prop is true', () => {
    render(<Button disabled>Click</Button>)
    expect(screen.getByRole('button')).toBeDisabled()
  })
})

API Integration Test Pattern

describe('GET /api/resources', () => {
  it('returns resources successfully', async () => {
    const request = new NextRequest('http://localhost/api/resources')
    const response = await GET(request)
    const data = await response.json()

    expect(response.status).toBe(200)
    expect(data.success).toBe(true)
    expect(Array.isArray(data.data)).toBe(true)
  })

  it('validates query parameters', async () => {
    const request = new NextRequest('http://localhost/api/resources?limit=invalid')
    const response = await GET(request)
    expect(response.status).toBe(400)
  })
})

E2E Test Pattern (Playwright)

import { test, expect } from '@playwright/test'

test('user can search and view results', async ({ page }) => {
  await page.goto('/')
  await page.fill('input[placeholder="Search"]', 'query')
  await page.waitForTimeout(600) // debounce

  const results = page.locator('[data-testid="result-card"]')
  await expect(results).toHaveCount(5, { timeout: 5000 })
})

Test File Organization

src/
├── components/
│   └── Button/
│       ├── Button.tsx
│       └── Button.test.tsx
├── app/api/
│   └── resources/
│       ├── route.ts
│       └── route.test.ts
└── e2e/
    └── flows.spec.ts

Mocking External Services

jest.mock('@/lib/supabase', () => ({
  supabase: {
    from: jest.fn(() => ({
      select: jest.fn(() => Promise.resolve({ data: [{ id: 1, name: 'Test' }], error: null }))
    }))
  }
}))

Coverage Thresholds

{
  "jest": {
    "coverageThresholds": {
      "global": { "branches": 80, "functions": 80, "lines": 80, "statements": 80 }
    }
  }
}

Common Mistakes to Avoid

// ❌ Testing implementation details
expect(component.state.count).toBe(5)

// ✅ Test user-visible behavior
expect(screen.getByText('Count: 5')).toBeInTheDocument()

// ❌ Brittle selectors
await page.click('.css-class-xyz')

// ✅ Semantic selectors
await page.click('button:has-text("Submit")')
await page.click('[data-testid="submit-button"]')

Remember: Tests are not optional. They are the safety net that enables confident refactoring, rapid development, and production reliability.