module that imports module can't solve path.

[matart15]

I have following structure

backend
    /shared_code/nodejs/node_modules/@shared_code/auth.ts
    /external_libraries/nodejs/package.json
    /lambdas/Query/doors/index.ts
    /lambdas/Query/doors/index.test.ts
    /tsconfig.json
    /jest.config.unit.js

When I run jest -c backend/jest.config.unit.js backend/lambdas/Query/doors/index.test.ts I get this error

    backend/shared_code/nodejs/node_modules/@shared_code/auth.ts:5
    import * as AWS from 'aws-sdk';
    ^^^^^^

    SyntaxError: Cannot use import statement outside a module

    > 5 | import { getCognitoUsername } from '@shared_code/auth';
        | ^

Problem

jest can solve '@shared_code/auth' path. but inside '@shared_code/auth' it can't solve aws-sdk path.

code details

Details

// tsconfig.json

{
  ...
    "paths": {
      "@prisma/*": [
        "../database/node_modules/@prisma/*"
      ],
      "@shared_code/*": [
        "shared_code/nodejs/node_modules/@shared_code/*"
      ],
      "@prisma_code/*": [
        "./create_prisma_client/nodejs/node_modules/@prisma_code/*"
      ],
      "aws-sdk": [
        "./external_libraries/nodejs/node_modules/aws-sdk"
      ],
      "aws-lambda": [
        "./external_libraries/nodejs/node_modules/aws-lambda"
      ],
    },
    ...
}

// jest.config.unit.js

   ...
  moduleNameMapper: {
    '^@prisma/(.*)$': '<rootDir>/../database/node_modules/@prisma/$1',
    '^@shared_code/(.*)$': '<rootDir>/shared_code/nodejs/node_modules/@shared_code/$1',
    '^@prisma_code/(.*)$': '<rootDir>/create_prisma_client/nodejs/node_modules/@prisma_code/$1',
    '^@aws-sdk$': '<rootDir>/external_libraries/nodejs/node_modules/aws-sdk',
    '^@aws-lambda$': '<rootDir>/external_libraries/nodejs/node_modules/aws-lambda',
  }
  ...

// shared_code/nodejs/node_modules/@shared_code/auth.ts

import * as AWS from 'aws-sdk';
import { AppSyncIdentityCognito, AppSyncResolverEvent } from 'aws-lambda';

export const getCognitoUserGroups = (event: AppSyncResolverEvent<any, Record<string, any> | null>): string[] => {
  const identity = getCognitoIdentity(event)
  const { claims } = identity;
  const userGroups: string[] = claims['cognito:groups']
  return userGroups;
}
...

// /lambdas/Query/doors/index.ts

import { getCognitoUsername } from '@shared_code/auth';
...
  const cognitoUsername = getCognitoUsername(event)
...

// /lambdas/Query/doors/index.test.ts

import { handler } from './index';

...

[AnderssonPeter]

I have the exact same error message but for import { register } from 'ol/proj/proj4';
The only pattern I can see is that the proj4 file is a js file without a .d.ts file, when I import a file that has a .d.ts file then it works as expected.

@matart15 did you manage to solve this issue?

[AnderssonPeter]

@kulshekhar I have recreated the issue here https://github.com/AnderssonPeter/jest-ts-issue
To recreate it just checkout the code and run npx jest and you will get the following output

 FAIL  ./test.spec.ts
  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    D:\Projects\jest-ts-issue\node_modules\ol\proj\proj4.js:4
    import Projection from './Projection.js';
    ^^^^^^

    SyntaxError: Cannot use import statement outside a module

      1 | import proj4 from 'proj4';
    > 2 | import { register } from 'ol/proj/proj4';
        | ^
      3 |
      4 | export default function setupProj4() {
      5 |     console.log('registering proj4')

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1728:14)
      at Object.<anonymous> (jest/proj4.ts:2:1)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        1.114 s
Ran all test suites.

The import of import proj4 from 'proj4'; works but import { register } from 'ol/proj/proj4'; does not.

Do you have any idea why? the only difference I can find is that proj4 has a ts definition file and ol/proj/proj4 does not.

[ahnpnl]

The error is about Jest runtime which doesn't resolve the module. ts-jest cannot do anything about it. You would need to:

• Either configure moduleNameMapper
• Or create a custom jest-resolve to workaround it.

[matart15]

@AnderssonPeter No I could not solve it.

I ended up mocking inner file.

[AnderssonPeter]

I'm not 100% sure but I added
jest.config.js
transformIgnorePatterns: ['/node_modules/(?!ol)/'] and
tsconfig.spec.json

    "ts-node": {
      "compilerOptions": {
        "module": "commonjs"
      }
    }

And it seems to be working now.