Setup a new Typescript project in Visual Studio Code with jest for testing. Inspiration from https://medium.com/@RupaniChirag/writing-unit-tests-in-typescript-d4719b8a0a40

typescript project with jest.md

Developer setup

Initialize with Google Typescript Style (gts)

npx gts init
npm i

Jest

npm i -D jest ts-jest @types/jest

In package.json add the scripts for test and coverage:

  "scripts": {
    "test": "jest",
    "coverage": "jest --coverage",
    ...
  }

Add a jest.config.js file:

module.exports = {
  transform: {'^.+\\.ts?$': 'ts-jest'},
  testEnvironment: 'node',
  testRegex: '/tests/.*\\.(test|spec)?\\.(ts|tsx)$',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node']
};

Visual Studio Code

In .vscode/launch.json add configuration to debug tests:

    {
      "type": "node",
      "request": "launch",
      "name": "Jest Current File",
      "program": "${workspaceFolder}/node_modules/.bin/jest",
      "args": ["${relativeFile}"],
      "console": "integratedTerminal",
      "internalConsoleOptions": "neverOpen",
      "windows": {
        "program": "${workspaceFolder}/node_modules/jest/bin/jest"
      }
    }

Optional (but worth it)

Add the Jest Text Explorer extension.

Add Coverage badge