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

Question

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.

Answer 1

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.