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Testing

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Write tests that give you confidence. Learn unit testing, integration testing, E2E testing, and best practices for reliable applications.

Free Tutorial

Testing Tutorial - Unit, Integration & E2E Testing

Learn how to write effective tests for web applications. Master the testing pyramid, write unit tests with Jest and Vitest, integration tests with React Testing Library, and E2E tests with Playwright for complete coverage.

Prerequisites

Before learning testing, you should be comfortable with JavaScript and have basic knowledge of React for component testing examples.

JavaScript Tutorial React Tutorial

What You'll Learn

✓ Testing fundamentals & pyramid
✓ Unit testing with Jest & Vitest
✓ Mocking, spies & test doubles
✓ React Testing Library
✓ Integration testing patterns
✓ E2E testing with Playwright
✓ CI/CD integration
✓ Testing best practices

Course Topics

Testing Fundamentals

Understanding why we test, types of testing, and building a testing mindset

The Testing Pyramid

Understanding the optimal balance of unit, integration, and E2E tests

Unit Testing Deep Dive

Master unit testing with Jest: mocking, spies, test organization, and best practices

Integration Testing

Test how components work together: API integration, database testing, and component interactions

End-to-End Testing

Test complete user workflows with Playwright and Cypress: browser automation, user interactions, and real-world scenarios

Testing Best Practices

Real-world testing strategies, common patterns, debugging techniques, and building maintainable test suites

End-to-End Testing with Playwright

Master Playwright for modern E2E testing with auto-waiting, parallel execution, and CI/CD integration for reliable browser tests

Test-Driven Development (TDD)

Learn the red-green-refactor cycle, writing tests first, and applying TDD to React components and API endpoints effectively

Mocking Strategies & Test Doubles

Master mocks, stubs, spies, and fakes to isolate units under test while avoiding over-mocking pitfalls in JavaScript testing

Test REST and GraphQL APIs with supertest, contract testing with Pact, authentication flows, and response validation strategies

Testing React Components

Use React Testing Library to test component behavior, user interactions, hooks, forms, and async patterns accessibly

Visual Regression Testing

Catch unintended visual changes with Chromatic, Percy, and Playwright screenshot comparisons integrated into CI pipelines

Performance & Load Testing

Load test your applications with k6 and Artillery, run stress and soak tests, identify bottlenecks, and set performance budgets

Testing with Databases

Set up test databases with fixtures, factories, Testcontainers, transaction rollback, and reliable cleanup between tests

Testing in CI/CD Pipelines

Configure GitHub Actions for automated testing, parallel execution, test splitting, flaky test management, and coverage gates

Accessibility Testing (a11y)

Automate accessibility audits with axe-core, jest-axe, Lighthouse, and Playwright to achieve WCAG compliance and inclusive design

Mutation Testing

Measure real test quality with Stryker mutation testing to find gaps that code coverage misses and strengthen your test suite

Testing Microservices

Test microservices with contract testing, service virtualization, Docker Compose integration, and chaos testing strategies

Testing Strategies & Anti-Patterns

Master the test pyramid, testing trophy, AAA pattern, test naming, isolation strategies, and learn when NOT to write tests

Why Testing Matters

🛡️

Confidence

Refactor and add features without fear of breaking existing functionality.

🐛

Catch Bugs Early

Find and fix issues before they reach production and affect users.

📚

Documentation

Tests serve as living documentation showing how your code should work.

Ready to Write Better Tests?

Begin your testing journey with unit testing fundamentals. You'll learn how to write your first tests with Jest and understand the testing mindset.

Start Learning Testing →