🧪 Test with Jest: Fast & Reliable Unit Testing for JavaScript

---

🧾 Course Description

Jest is the most popular testing framework for JavaScript applications — especially in the React and Node.js ecosystem. In “Test with Jest”, you’ll learn how to write unit tests, snapshot tests, and mock dependencies to ensure your code works reliably, every time.

This hands-on course helps developers build confidence in their JS/TS codebases using Jest’s powerful APIs, fast execution, and simple syntax. From basic assertions to asynchronous testing, mocking, and test coverage, this course equips you with everything needed to test modern frontend and backend apps.

---

✅ Key Benefits

• ⚡ Blazing-Fast Testing — Run lightweight, in-memory tests with zero config
• 🔒 Write Bug-Free Code — Catch regressions and failures early
• 📦 Out-of-the-Box Magic — Built-in assertion library, coverage reports, and mocking
• 🔁 Great for React & Node — Preferred choice for full-stack JavaScript apps
• 🧰 CI-Friendly — Works well with GitHub Actions, GitLab CI, CircleCI, etc.

---

🎯 Pre-requisites

• Familiarity with JavaScript or TypeScript (functions, variables, objects, arrays)
• Basic knowledge of Node.js and package managers (npm, yarn)
• Optional: experience with React or APIs is helpful
• No prior testing experience needed

---

📚 Curriculum Breakdown

📘 Module 1: Introduction to Testing with Jest

• Why testing matters
• Installing Jest in a Node.js or React project
• Writing and running your first test

🧪 Module 2: Core Testing Concepts

• The AAA pattern: Arrange, Act, Assert
• Matchers and assertions (toBe, toEqual, toContain, etc.)
• Grouping tests with describe, beforeEach, afterEach

🧱 Module 3: Mocking and Spies

• Manual and automatic mocks
• Using jest.fn(), jest.mock()
• Asserting calls, parameters, return values

🔁 Module 4: Asynchronous Testing

• Testing promises and async/await functions
• Using done(), resolves/rejects, and async functions
• Testing APIs and database calls

🧪 Module 5: Snapshot Testing

• Snapshot test basics
• Best practices and snapshot updating
• Use cases in React, UI components

📊 Module 6: Code Coverage and Debugging

• Generating coverage reports
• Understanding uncovered branches/lines
• Debugging failing tests

🧰 Module 7: Integrating with CI and Git Hooks

• Running tests on pre-commit (husky, lint-staged)
• Using Jest with GitHub Actions or GitLab CI
• Test report output formats

🧪 Module 8: Final Project

• Mini Test Suite for a Node.js Utility or React Component
  • Write unit and async tests
  • Add mock functions
  • Include snapshots (optional)
  • Generate and analyze test coverage

---

⏱️ Estimated Duration

Daily Study Time	Estimated Duration	Ideal For
2 hours/day	8–10 days (~2 weeks)	Part-time with examples
4 hours/day	4–5 days (1 week)	Ideal for rapid learners
6 hours/day	2–3 days (bootcamp)	Immersive with hands-on focus

---

🎓 Outcome

By the end of Test with Jest, you will:

• Write efficient, readable, and reusable unit tests
• Mock functions, modules, and APIs for isolation
• Perform snapshot and asynchronous testing
• Automate testing as part of your dev workflow and CI/CD pipelines