12^th Practical Class:
Unit Testing

Unit Testing: Jest

• Jest is JavaScript Testing Framework
• https://jestjs.io/
• already part of Create React App

Simple Unit Test

/sum.js:

/__tests__/sum.js:

• run yarn test

  • it will find all tests in your project

• docs for describe(), it(), and others

• docs for expect(), toBe(), and others

React Testing Library

• https://testing-library.com/docs/react-testing-library/intro
• How to use React Testing Library Tutorial

change package.json > "scripts" > "test" to:

src/organisms/__tests__/SingUpForm.js:

Game Of Life

For more information visit the Conway's Game of Life page at Wikipedia.

Rule # 1

Any live cell with fewer than two live neighbors dies, as if by underpopulation.

generation x + 1

Rule # 2

Any live cell with two or three live neighbors lives on to the next generation.

generation x (n = 2,3)

generation x + 1

Rule # 3

Any live cell with more than three live neighbors dies, as if by overpopulation.

generation x (n > 3)

generation x + 1

Rule # 4

Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction.

generation x (n = 3)

generation x + 1

All Rules:

Test Drivend Deveopment (TDD)

1. Write Failing Test
2. Fix Tests
3. Refactor
   repeat!

TDD Cycle

1. Write Failing Test

2. Fix Failing Test
(as fast as possible)

• change code so all tests passes

3. Refactor

• refactor code (or tests too)
• all tests must pass

5. Write Failing Test
(repeat!)