Science Knowings: JavaScript Course For Social Media

Unit Testing with Jest

Unit Testing with Jest

Welcome to Unit Testing with Jest!
In this session, we'll explore the power of Jest, a popular JavaScript testing framework, to ensure the quality and reliability of your code.

Getting Started with Jest

  • Install Jest using npm (npm install --save-dev jest)
  • Create a new test file with a .test.js extension
  • Follow the Jest syntax and conventions
  • Creating Test Suites and Test Cases

  • Group related tests into test suites (describe())
  • Define individual test cases using it()
  • Use descriptive names for test cases
  • Writing Assertions

    • Use Jest's built-in assertions like expect() and toBe()
    • Verify the expected output matches the actual results
    • Assertions help you detect and debug errors

    Mocking Functions with Jest

    • Replace real functions with mock functions (jest.fn())
    • Control the behavior of mocked functions
    • Verify if mocked functions were called with the expected arguments

    Testing Asynchronous Code

    • Use Jest's async and await keywords
    • Handle promises and callbacks in your tests
    • Ensure your tests run in a controlled environment

    Debugging Tests

    • Use Jest's debugging tools (debugger, console.log())
    • Inspect variables and values during test execution
    • Identify and fix errors quickly

    Organizing and Scaling Your Tests

    • Create a dedicated test directory
    • Use a consistent naming convention for test files
    • Break down large tests into smaller modules

    Best Practices for Unit Testing

    • Test small units of code (functions, classes)
    • Write atomic tests that focus on a specific behavior
    • Keep tests independent and avoid shared state
    • Use version control for your tests

    Next Topic: End-to-End Testing with Cypress

    In our next session, we'll explore Cypress, a powerful tool for End-to-End testing of your web applications. Follow us to learn more!