How to use at modules imports (@) in Jest's globalSetup function with TypeScript?

Using JS hook to invoke TS setupGlobal function (which is using at modules imports, e.g @app/blablabla.ts), I'm getting an error Cannot find module '@config/config'. I've described moduleNameMapper and it's working in tests, but seems it is not in setupGlobal function. How can I fix that?

As I wrote, the moduleNameMapper is described and Jest can understand those (at modules) imports in tests.

jest.config.js

module.exports = {
  roots: ['<rootDir>/src'],
  transform: {
    '^.+\\.tsx?$': 'ts-jest',
  },
  testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
  moduleDirectories: ['node_modules', 'src'],
  moduleNameMapper: {
    '@tests-suite/(.*)': '<rootDir>/src/tests/tests-suite/$1',
    '@config/(.*)': '<rootDir>/config/$1',
    '@tests/(.*)': '<rootDir>/src/tests/$1',
    '@src/(.*)': '<rootDir>/src/$1',
  },
  globalSetup: "<rootDir>/src/tests/unit/jestGlobalSetup.js"
}

jestGlobalSetup.js

require("ts-node/register");
module.exports = require('./setupTestEnvironment').default;

setupTestEnvironment.ts

import { dbConnectionManager } from '@src/dbConnectionManager'

// tslint:disable-next-line:no-default-export
export default async () => {
  if (process.env.NODE_ENV === 'test') {
    setupTestEnvironment()
  }
}

const setupTestEnvironment = async () => {
  await dbConnectionManager.awaitConnection()
}

I'm expecting that "at module" imports would be executed in setupGlobal function, but it throws the error.

Solution

Okay. The problem is we were using absolute paths got solved by installing ts-jest and adding the next jest.config.js:

    module.exports = {
  roots: [
    '<rootDir>/src',
  ],
  testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$',
  moduleFileExtensions: [
    'js',
    'json',
    'jsx',
    'node',
    'ts',
    'tsx',
  ],
  moduleDirectories: [
    'node_modules',
    'src',
  ],
  moduleNameMapper: {
    '^@tests\\-suite/(.*)$': '<rootDir>/src/tests/tests-suite/$1',
    '^@admin/(.*)$': '<rootDir>/src/admin/$1',
    '^@common/(.*)$': '<rootDir>/src/common/$1',
    '^@app/(.*)$': '<rootDir>/src/app/$1',
    '^@partners/(.*)$': '<rootDir>/src/partners/$1',
    '^@config/(.*)$': '<rootDir>/config/$1',
    '^@tests/(.*)$': '<rootDir>/src/tests/$1',
    '^@src/(.*)$': '<rootDir>/src/$1',
  },
  setupFilesAfterEnv: [`<rootDir>/src/tests/setup/GlobalSetup.ts`],
  preset: 'ts-jest',
  testMatch: null,
};

And our run script looks like this "test:jest": "NODE_ENV=test yarn ts-node -r tsconfig-paths/register ./src/tests/setup/testInit.ts"

And testInit looks like this;

import { runCLI } from 'jest'

// globalSetup
async function init() {
  console.log('Initialization')

  await runCLI({ config: './jest.config.js', watch: true } as any, [__dirname])

  // Do all your initialization stuff
  // I use a setTimeout to simulate true async
  return new Promise<void>((resolve, _reject) => {
    setTimeout(() => {
      console.log('Init finished')
      resolve()
    }, 1000)
  })
}

// globalTeardown
async function afterTests(): Promise<void> {
  console.log('End of tests - Execute something')
}

init()
  .then(() => {
    afterTests()
  })
  // tslint:disable-next-line:no-console
  .catch(e => console.error(e))

GlobalSetup.ts looks like this:

import { DBConnectionManager } from '@src/DBConnectionManager'

beforeAll(async () => {
  await DBConnectionManager
  .awaitConnection()
})

So the DBConnectionManager is just a wrapper around TypeORM, which gives us a connection. It is get connected before each test to hit the real test DB. It works for now.