README.md

Summary of JavaScript Concepts Covered in These Exercises

1. Unit Testing Fundamentals:

   • The purpose of unit tests and how they fit into the software development lifecycle.
   • Differences between manual testing and automated unit testing.
   • Test-driven development (TDD) and the benefits of writing unit tests first.

2. Jest Basics:

   • Installing Jest and setting it up for a project using npm.
   • Writing simple unit tests using Jest's test and expect functions.
   • Understanding matchers and how to use them for various types of assertions.
   • Running Jest tests using the command line and configuring Jest with a configuration file.

3. Test File Organization:

   • Structuring test files using describe blocks to group related tests.
   • Using hooks (beforeAll, afterAll, beforeEach, afterEach) to perform setup and teardown tasks.

4. Common Matchers in Jest:

   • Using matchers like toBe, toEqual, toStrictEqual, toContain, toMatch, toBeTruthy, toBeFalsy, and toThrow.
   • Differences between strict and loose equality checks in Jest.

5. Mocking and Spying:

   • Creating mock functions to isolate tests and avoid dependencies on external services.
   • Using Jest's automock feature to automatically mock modules.
   • Writing manual mocks to customize the behavior of mocked functions.
   • Using spies to monitor calls to functions and assert they were called correctly.

6. Testing Asynchronous Code:

   • Writing tests for asynchronous functions using Promises, async/await, and callbacks.
   • Using Jest's resolves and rejects for testing promise-based code.
   • Ensuring tests wait for asynchronous code to complete using Jest's done callback.

7. Code Coverage:

   • Measuring code coverage and understanding metrics like statement, branch, function, and line coverage.
   • Collecting coverage statistics using Jest and configuring thresholds to enforce code quality.