TypeScript tests using jest

index.test.ts

import * as lib from './'

test('test', async () => {
  expect(await lib.hello()).toBe('world')
})

index.ts

export const hello = async ():string => {
  return 'world'
}

install.sh

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

jest.config.js

module.exports = {
  "roots": [
    "src"
  ],
  "transform": {
    "^.+\\.tsx?$": "ts-jest"
  },
}

package.json

{
  "scripts": {
    "test": "jest"
  }
}