Test Driven Development Workflow

--- name: tdd-workflow description: > Use this skill when writing new features, fixing bugs, or refactoring code. Enforces test-driven development with 80%+ coverage including unit, integration, and E2E tests. metadata: origin: ECC version: "1.0" --- # Test-Driven Development Workflow This skill ensures all code development follows TDD principles with comprehensive test coverage. ## 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, then implement code to make tests pass. ### 2. Coverage Requirements - Minimum 80% coverage (unit + integration + E2E) - All edge cases covered - Error scenarios tested - Boundary conditions verified ### 3. Test Types #### Unit Tests - Individual functions and utilities - Component logic - Pure functions - Helpers and utilities #### Integration Tests - API endpoints - Database operations - Service interactions - External API calls #### E2E Tests (Playwright) - Critical user flows - Complete workflows - Browser automation - UI interactions ## TDD Workflow Steps ### Step 1: Write User Journeys `` As a [role], I want to [action], so that [benefit] Example: As a user, I want to search for markets semantically, so that I can find relevant markets even without exact keywords. ` ### Step 2: Generate Test Cases For each user journey, create comprehensive test cases: `typescript describe('Semantic Search', () => { it('returns relevant markets for query', async () => { // Test implementation }) it('handles empty query gracefully', async () => { // Test edge case }) it('falls back to substring search when Redis unavailable', async () => { // Test fallback behavior }) it('sorts results by similarity score', async () => { // Test sorting logic }) }) ` ### Step 3: Run Tests (They Should Fail) `bash npm test # Tests should fail - we haven't implemented yet ` ### Step 4: Implement Code Write minimal code to make tests pass: `typescript // Implementation guided by tests export async function searchMarkets(query: string) { // Implementation here } ` ### Step 5: Run Tests Again `bash npm test # Tests should now pass ` ### Step 6: Refactor Improve code quality while keeping tests green: - Remove duplication - Improve naming - Optimize performance - Enhance readability ### Step 7: Verify Coverage `bash npm run test:coverage # Verify 80%+ coverage achieved ` ## Testing Patterns ### Unit Test Pattern (Jest/Vitest) `typescript 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 onClick={handleClick}>Click</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 `typescript import { NextRequest } from 'next/server' import { GET } from './route' describe('GET /api/markets', () => { it('returns markets successfully', async () => { const request = new NextRequest('http://localhost/api/markets') 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/markets?limit=invalid') const response = await GET(request) expect(response.status).toBe(400) }) it('handles database errors gracefully', async () => { // Mock database failure const request = new NextRequest('http://localhost/api/markets') // Test error handling }) }) ` ### E2E Test Pattern (Playwright) ``typescript import { test, expect } from '@playwright/test' test('user can search and filter markets', async ({ page }) => { // Navigate to markets page await page.goto('/') await page.click('a[href="/markets"]') // Verify page loaded await expect(page.locator('h1')).toContainText('Markets') // Search for markets await page.fill('input[placeholder="Search markets"]', 'election') // Wait for debounce and results await page.waitForTimeout(600) // Verify search results displayed const results = page.locator('[data-testid="market-card"]') await expect(results).toHaveCount(5, { timeout: 5000 }) // Verify results contain search term const firstResult = results.first() await expect(firstResult).t