Jest with tyescript in monorepo doesn't work with dependency out of the root folder

Question

I use Jest with Typescript. I want to create a monorepo. My folders structure is:

fe
|-app1
|--.jest.config.ts
|--tsconfig.json
|-shared
|--dummyData.ts

I want a unit test from app1 to access some data from shared folder.

fe/app1/demo.spec.ts:

import { someData } from '@shared/dummyData' //<--HERE: the alias is works, but jest can not understand "export" keyword

descrube('demo' () => {
  it('demo test', () => {
    expect(someData).toBe('DUMMY'));
  })
})

fe/shared/dummyData.ts:

export const someData = 'DUMMY';

The problem is that jest throws an error:

Jest encountered an unexpected token
{"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){export const someData = 'DUMMY';
                                                                                        ^^^^^^

As I understand it cannot parse typescript or es6 modules that were produced by ts and babel. The thing that it works fine while shared folder is inside app1, but once it's outside (and outside the root folder, i.g '<rootDir>/../shared/$1') it start throwing that error.

---

Here is my configs:

I described alias in fe/app1/tsconfig.json:

{
  ...
  "compilerOptions": {
    "target": "esnext",
    "module": "esnext", 
    "paths": {
      "@/*": ["app/src/*"],
      "@shared/*": ["shared/*"]
    }
  }
}

And in fe/app1/.jest.config.ts:

module.exports = {
...
  transform: {
    '^.+\\.js$': '<rootDir>/node_modules/babel-jest',
    '^.+\\.(jsx?|tsx?)$': 'ts-jest'
  },
  moduleNameMapper: {
    '^@/(.*)$': '<rootDir>/src/$1',
    '^@shared/(.*)$': '<rootDir>/../shared/$1',
  }
}

---

Some thoughts:

• As I understand I have to tell to jest to apply same parsers (babel, etc) for the code outside of the rootDir.
• I guess it's possible to create a tsconfig in the root folder(fe), but I want to launch unit tests from fe/app1 folder...
• Maybe it's possible to configure the things with such properties as projects, roots and etc, but I'm out of luck so far.

Answer 1

Okay, I found the solution:

For monorepo it is important to have babel config as a JS file

So, simply rename .babelrc to babel.config.js (in the folder you called jest from, in my case it is fe/app1)

For more info you could check this comment (and maybe this thread)