class-notes.md

Class notes Chapter-13 Time for the test (05/02/2023)

How to test react applications ? Jest & React Testing Library (alternative to enzyme)

How to setup test for our app ?

Why test cases ?

1. New code should not old code
2. Not breaking existing code - Maintainability

TDD - test Driven Development ? Test cases even before writing code, development becomes very slow.

Types of tesing :

1. Manual testing -> human testing the code

2. Automated testing -> code testing the code Eg: Selenium

3. E2E tetsing -> test the whole flow by stimulating . Eg:cypress This is offloaded to QA team. Headless browser -> browser does not have to do teh work of laoding UI in browser. It makes testing faster.

4. Unit testing -> core job of developers -> testing small unit of code

5. Integration testing -> Data flow between components

6. Performance, Regression and Smoke testing

React-Testing-library

1. Install React Testing library - npm install --save-dev @testing-library/react @testing-library/jest-dom

2. Install Jest - npm install -D jest

3. Configure Jest -> npx jest --init

4. Typescript -> N

5. environment -> jsdom (broswer-like)

6. code coverage -> y

7. provider for coverage -> babel

8. automatically clear before test -> y

9. Creates jest.config.js

10. scripts -> test : jest

11. npm install -D jest-environment-jsdom

12. jest is trying to find test cases in the app under tests folder

13. Create first test -> sum.test.js under tests folder

14. test("testcase name ", () => { })

15. Every test case should have some assertion - expect to return - toBe expeect(sum(2,3)).toBe(5)

16. import sum.js (component) inside sum.test.js

17. npm install --save-dev babel-jest @babel/core @babel/preset-env - why ? because jest does not understand import statement.

18. to configure babel -> babelrc file or babel.config.js

19. package.json ->in scripts watch test : "test --watch"