Import Absolute Paths in Typescript Jest Tests

In order to avoid this:

// project/__tests__/stuff/someDistantCousin.test.ts
import { thing } from '../../src/stuff/someDistantCousin'
import { wrapFunction } from '../testUtils/firebase'

And to write this instead:

import { thing } from 'src/stuff/someDistantCousin'
import { wrapFunction } from 'tests/testUtils/firebase'

There are 2 things to configure:

1. Jest Config (i.e. jest.config.js, package.json, etc...)
2. Typscript Config: tsconfig.json

jest.config.js

module.exports = {
  moduleNameMapper: {
    'src/(.*)': '<rootDir>/src/$1',
    'tests/(.*)': '<rootDir>/__tests__/$1',
  },
}

tsconfig.json

{
  "compilerOptions": {
    "baseUrl": "./",
    "paths": {
      "src/*": ["src/*"],
      "tests/*": ["__tests__/*"]
    }
  }
}