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

references/testing_strategies.md

references/test_automation_patterns.md

references/qa_best_practices.md

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

Troubleshooting

.tsx

.jsx

export const

export function

coverage-final.json

lcov.info

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

page.tsx

index.tsx

src/app/

pages/

.test.tsx

coveragePathIgnorePatterns

jest.config.js

webServer

playwright.config.ts

timeout

--strict

coverage_analyzer.py

--strict

Success Criteria

• Code coverage above 80% across statements, branches, functions, and lines for all non-trivial source files.
• Zero critical coverage gaps in authentication, payment, and security modules as reported by

  coverage_analyzer.py --critical-paths

  .
• 100% of React components have at least a render test confirming they mount without crashing.
• All E2E tests pass on Chromium, Firefox, and WebKit in CI before merge to main.
• Branch coverage above 75% for service layers, API handlers, and middleware modules.
• No flaky tests -- every test in the suite produces deterministic results across 3 consecutive CI runs.
• Test generation covers all detected routes -- the E2E scaffolder accounts for every page route in the Next.js application, including dynamic segments.

Scope & Limitations

This skill covers:

• Unit test stub generation for React/TypeScript functional and class components using Jest and React Testing Library.
• Coverage analysis and gap identification from Istanbul JSON and LCOV report formats.
• E2E test scaffolding for Next.js App Router and Pages Router projects using Playwright.
• Accessibility test generation via

  jest-axe

  integration.

This skill does NOT cover:

• Backend API testing (see

  senior-backend

  for Express/Node.js testing patterns).
• Performance or load testing (see

  senior-devops

  for infrastructure and performance tooling).
• Visual regression testing or screenshot comparison workflows.
• Mobile-native testing (React Native, Flutter) -- this skill targets web browser-based testing only.

Integration Points

senior-frontend

test_suite_generator.py

senior-fullstack

coverage_analyzer.py

senior-devops

e2e_test_scaffolder.py

playwright.config.ts

code-reviewer

coverage_analyzer.py

tdd-guide

test_suite_generator.py --scan-only

qa-browser-automation

e2e_test_scaffolder.py --include-pom

Tool Reference

1. test_suite_generator.py

Purpose: Scans React/TypeScript source directories for components and generates Jest + React Testing Library test stubs with render tests, prop tests, interaction tests, state tests, and optional accessibility tests.

Usage:

python scripts/test_suite_generator.py <source> [options]

Flags:

source

--output

-o

<source>/__tests__/

--include-a11y

false

jest-axe

--scan-only

false

--template

None

--verbose

-v

false

--json

false

Example:

python scripts/test_suite_generator.py src/components/ \
  --output __tests__/ \
  --include-a11y \
  --verbose

# Scanning: src/components/
# Found 24 React components
#   Button.test.tsx (4 test cases)
#   Modal.test.tsx (3 test cases)
#   ...
# Summary: 24 test files, 87 test cases

Output Formats:

• Default (text): Human-readable summary printed to stdout listing each generated file and test case count.
• JSON (

  --json

  ): Structured object with

  status

  ,

  components

  (array of detected component metadata),

  generated_files

  (array of output paths), and

  summary

  (totals).

2. coverage_analyzer.py

Purpose: Parses Jest/Istanbul coverage reports (JSON or LCOV format), identifies coverage gaps by severity, flags critical business-logic paths, and generates actionable recommendations in text, HTML, or JSON format.

Usage:

python scripts/coverage_analyzer.py <coverage> [options]

Flags:

coverage

.json

.info

--threshold

-t

80

--strict

false

--critical-paths

false

--format

-f

text

text

html

json

--output

-o

None

--verbose

-v

false

--json

false

--format

Example:

python scripts/coverage_analyzer.py coverage/coverage-final.json \
  --threshold 80 \
  --strict \
  --format html \
  --output report.html

# Analyzing coverage from: coverage/coverage-final.json
# Found coverage data for 42 files
# Report written to: report.html

Output Formats:

• Text (

  --format text

  ): Structured report with overall percentages, threshold pass/fail, critical gaps, files below threshold, and prioritized recommendations.
• HTML (

  --format html

  ): Styled HTML report with color-coded coverage stats, gap severity table, and per-file breakdown. Suitable for CI artifact upload.
• JSON (

  --json

  ): Summary object with

  status

  (pass/fail),

  threshold

  ,

  coverage

  (statement/branch/function/line percentages),

  files_analyzed

  ,

  files_below_threshold

  ,

  total_gaps

  , and

  critical_gaps

  .

3. e2e_test_scaffolder.py

Purpose: Scans Next.js App Router or Pages Router directories, detects routes (including dynamic segments, route groups, and authenticated pages), and generates Playwright test files with navigation, form, auth, and interaction test stubs. Optionally generates Page Object Model classes and Playwright configuration.

Usage:

python scripts/e2e_test_scaffolder.py <source> [options]

Flags:

source

src/app/

pages/

--output

-o

e2e/

--include-pom

false

<output>/pages/

--routes

None

"/login,/dashboard"

--verbose

-v

false

--json

false

Example:

python scripts/e2e_test_scaffolder.py src/app/ \
  --output e2e/ \
  --include-pom \
  --routes "/login,/dashboard,/checkout"

# Scanning: src/app/
# Found 3 routes
#   auth-login.spec.ts
#   pages/AuthLoginPage.ts
#   dashboard.spec.ts
#   pages/DashboardPage.ts
#   checkout.spec.ts
#   pages/CheckoutPage.ts
#   fixtures/auth.ts
#
# Summary: 3 routes, 8 files generated

Output Formats:

• Default (text): Human-readable list of generated files and a route/file count summary.
• JSON (

  --json

  ): Structured object with

  status

  ,

  routes

  (array of route metadata including path, type, params, form/auth detection),

  generated_files

  (array with type, route, and path), and

  summary

  (totals and configuration flags).

Generated Artifacts:

• <route>.spec.ts

  -- Playwright test file per route with contextual test cases.

• pages/<RouteName>Page.ts

  -- Page Object Model class (when

  --include-pom

  is set).

• playwright.config.ts

  -- Multi-browser configuration with dev server integration (generated once if not already present).

• fixtures/auth.ts

  -- Authentication fixture with UI and API login patterns (generated once if not already present).