Senior QA Engineer

Test automation, coverage analysis, and quality assurance patterns for React and Next.js applications.

Table of Contents

• Quick Start

• Tools Overview

• Test Suite Generator

• Coverage Analyzer

• E2E Test Scaffolder

• QA Workflows

• Unit Test Generation Workflow

• Coverage Analysis Workflow

• E2E Test Setup Workflow

• Reference Documentation

• Common Patterns Quick Reference

Quick Start

Generate Jest test stubs for React components

python scripts/test_suite_generator.py src/components/ --output tests/

Analyze test coverage from Jest/Istanbul reports

python scripts/coverage_analyzer.py coverage/coverage-final.json --threshold 80

Scaffold Playwright E2E tests for Next.js routes

python scripts/e2e_test_scaffolder.py src/app/ --output e2e/

Tools Overview

1. Test Suite Generator

Scans React/TypeScript components and generates Jest + React Testing Library test stubs with proper structure.

Input: Source directory containing React components Output: Test files with describe blocks, render tests, interaction tests

Usage:

Basic usage - scan components and generate tests

python scripts/test_suite_generator.py src/components/ --output tests/

Output:

Scanning: src/components/

Found 24 React components

Generated tests:

tests/Button.test.tsx (render, click handler, disabled state)

tests/Modal.test.tsx (render, open/close, keyboard events)

tests/Form.test.tsx (render, validation, submission)

...

Summary: 24 test files, 87 test cases

Include accessibility tests

python scripts/test_suite_generator.py src/ --output tests/ --include-a11y

Generate with custom template

python scripts/test_suite_generator.py src/ --template custom-template.tsx

Supported Patterns:

• Functional components with hooks

• Components with Context providers

• Components with data fetching

• Form components with validation

2. Coverage Analyzer

Parses Jest/Istanbul coverage reports and identifies gaps, uncovered branches, and provides actionable recommendations.

Input: Coverage report (JSON or LCOV format) Output: Coverage analysis with recommendations

Usage:

Analyze coverage report

python scripts/coverage_analyzer.py coverage/coverage-final.json

Output:

=== Coverage Analysis Report ===

Overall: 72.4% (target: 80%)

BY TYPE:

Statements: 74.2%

Branches: 68.1%

Functions: 71.8%

Lines: 73.5%

CRITICAL GAPS (uncovered business logic):

src/services/payment.ts:45-67 - Payment processing

src/hooks/useAuth.ts:23-41 - Authentication flow

RECOMMENDATIONS:

1. Add tests for payment service error handling

2. Cover authentication edge cases

3. Test form validation branches

Files below threshold (80%):

src/components/Checkout.tsx: 45%

src/services/api.ts: 62%

Enforce threshold (exit 1 if below)

python scripts/coverage_analyzer.py coverage/ --threshold 80 --strict

Generate HTML report

python scripts/coverage_analyzer.py coverage/ --format html --output report.html

3. E2E Test Scaffolder

Scans Next.js pages/app directory and generates Playwright test files with common interactions.

Input: Next.js pages or app directory Output: Playwright test files organized by route

Usage:

Scaffold E2E tests for Next.js App Router

python scripts/e2e_test_scaffolder.py src/app/ --output e2e/

Output:

Scanning: src/app/

Found 12 routes

Generated E2E tests:

e2e/home.spec.ts (navigation, hero section)

e2e/auth/login.spec.ts (form submission, validation)

e2e/auth/register.spec.ts (registration flow)

e2e/dashboard.spec.ts (authenticated routes)

e2e/products/[id].spec.ts (dynamic routes)

...

Generated: playwright.config.ts

Generated: e2e/fixtures/auth.ts

Include Page Object Model classes

python scripts/e2e_test_scaffolder.py src/app/ --output e2e/ --include-pom

Generate for specific routes

python scripts/e2e_test_scaffolder.py src/app/ --routes "/login,/dashboard,/checkout"

QA Workflows

Unit Test Generation Workflow

Use when setting up tests for new or existing React components.

Step 1: Scan project for untested components

python scripts/test_suite_generator.py src/components/ --scan-only

Step 2: Generate test stubs

python scripts/test_suite_generator.py src/components/ --output tests/

Step 3: Review and customize generated tests

// tests/Button.test.tsx (generated) import { render, screen, fireEvent } from '@testing-library/react'; import { Button } from '../src/components/Button';

describe('Button', () => { it('renders with label', () => { render(<Button>Click me</Button>); expect(screen.getByRole('button', { name: /click me/i })).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); });

// TODO: Add your specific test cases });

Step 4: Run tests and check coverage

npm test -- --coverage python scripts/coverage_analyzer.py coverage/coverage-final.json

Coverage Analysis Workflow

Use when improving test coverage or preparing for release.

Step 1: Generate coverage report

npm test -- --coverage --coverageReporters=json

Step 2: Analyze coverage gaps

python scripts/coverage_analyzer.py coverage/coverage-final.json --threshold 80

Step 3: Identify critical paths

python scripts/coverage_analyzer.py coverage/ --critical-paths

Step 4: Generate missing test stubs

python scripts/test_suite_generator.py src/ --uncovered-only --output tests/

Step 5: Verify improvement

npm test -- --coverage python scripts/coverage_analyzer.py coverage/ --compare previous-coverage.json

E2E Test Setup Workflow

Use when setting up Playwright for a Next.js project.

Step 1: Initialize Playwright (if not installed)

npm init playwright@latest

Step 2: Scaffold E2E tests from routes

python scripts/e2e_test_scaffolder.py src/app/ --output e2e/

Step 3: Configure authentication fixtures

// e2e/fixtures/auth.ts (generated) import { test as base } from '@playwright/test';

export const test = base.extend({ authenticatedPage: async ({ page }, use) => { await page.goto('/login'); await page.fill('[name="email"]', 'test@example.com'); await page.fill('[name="password"]', 'password'); await page.click('button[type="submit"]'); await page.waitForURL('/dashboard'); await use(page); }, });

Step 4: Run E2E tests

npx playwright test npx playwright show-report

Step 5: Add to CI pipeline

.github/workflows/e2e.yml

• name: Run E2E tests run: npx playwright test
• name: Upload report uses: actions/upload-artifact@v3 with: name: playwright-report path: playwright-report/

Reference Documentation

File Contains Use When

references/testing_strategies.md

Test pyramid, testing types, coverage targets, CI/CD integration Designing test strategy

references/test_automation_patterns.md

Page Object Model, mocking (MSW), fixtures, async patterns Writing test code

references/qa_best_practices.md

Testable code, flaky tests, debugging, quality metrics Improving test quality

Common Patterns Quick Reference

React Testing Library Queries

// Preferred (accessible) screen.getByRole('button', { name: /submit/i }) screen.getByLabelText(/email/i) screen.getByPlaceholderText(/search/i)

// Fallback screen.getByTestId('custom-element')

Async Testing

// Wait for element await screen.findByText(/loaded/i);

// Wait for removal await waitForElementToBeRemoved(() => screen.queryByText(/loading/i));

// Wait for condition await waitFor(() => { expect(mockFn).toHaveBeenCalled(); });

Mocking with MSW

import { rest } from 'msw'; import { setupServer } from 'msw/node';

const server = setupServer( rest.get('/api/users', (req, res, ctx) => { return res(ctx.json([{ id: 1, name: 'John' }])); }) );

beforeAll(() => server.listen()); afterEach(() => server.resetHandlers()); afterAll(() => server.close());

Playwright Locators

// Preferred page.getByRole('button', { name: 'Submit' }) page.getByLabel('Email') page.getByText('Welcome')

// Chaining page.getByRole('listitem').filter({ hasText: 'Product' })

Coverage Thresholds (jest.config.js)

module.exports = { coverageThreshold: { global: { branches: 80, functions: 80, lines: 80, statements: 80, }, }, };

Common Commands

Jest

npm test # Run all tests npm test -- --watch # Watch mode npm test -- --coverage # With coverage npm test -- Button.test.tsx # Single file

Playwright

npx playwright test # Run all E2E tests npx playwright test --ui # UI mode npx playwright test --debug # Debug mode npx playwright codegen # Generate tests

Coverage

npm test -- --coverage --coverageReporters=lcov,json python scripts/coverage_analyzer.py coverage/coverage-final.json