modbender Senior QA Engineer
Test automation, coverage analysis, and quality assurance patterns for React and Next.js applications.
Table of Contents
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
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