jest-resolve can't handle "exports"

🐛 Bug Report

“exports” field seems to be ignored by jest-resolve, resulting with unexpected “Cannot find module …” error thrown even though Node is capable of resolving the paths.

https://nodejs.org/api/esm.html#esm_package_entry_points

To Reproduce

Steps to reproduce the behavior:

I have a simple utils package in my workspace, that’s shaped like this:

/dist
  array.js
  … 
/src
  array.js
  …
package.json

package.json:

{
  "name": "@my-org/utils",
  "version": "1.0.0",
  "exports": {
    "./array": "./dist/array.js",
    "./boolean": "./dist/boolean.js",
    "./math": "./dist/math.js",
    "./number": "./dist/number.js",
    "./object": "./dist/object.js",
    "./promise": "./dist/promise.js",
    "./string": "./dist/string.js"
  }
}

This allows me to use it in my main project by importing utils like this:

import { min } from '@my-org/utils/math'

This works both in native ES modules environment in Node 14, and in code transpiled by Babel. But this code crashes in Jest tests.

Expected behavior

“exports” to be respected and understood by jest-resolve

Link to repl or repo (highly encouraged)

https://github.com/wojtekmaj/resolve-exports-issue

envinfo

  System:
    OS: macOS 11.0
    CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
  Binaries:
    Node: 14.5.0 - /usr/local/bin/node
    Yarn: 2.1.1 - /usr/local/bin/yarn
    npm: 6.14.5 - /usr/local/bin/npm
  npmPackages:
    jest: ^26.4.0 => 26.4.0 

[guilleflmpeya]

I found this post after the same happened to me. I´m using node 12.22.1 Client project dependencies

"devDependencies": {
    "@babel/cli": "^7.13.14",
    "@babel/core": "^7.13.15",
    "@babel/node": "^7.13.13",
    "@babel/preset-env": "^7.13.15",
    "@types/jest": "^26.0.22",
    "babel-jest": "^26.6.3",
    "babel-loader": "^8.2.2",
    "circular-dependency-plugin": "^5.2.2",
    "enhanced-resolve": "^5.8.0",
    "jest": "^26.6.3",
    "jest-sonar-reporter": "^2.0.0",
    "npm-run-all": "^4.1.5",
    "sonarqube-scanner": "^2.8.0",
    "webpack": "^5.33.1",
    "webpack-bundle-analyzer": "^4.4.1",
    "webpack-cli": "^4.6.0"
  }

exporter lib config

"main": "./lib/main.js",
  "exports": {
    ".": "./lib/main.js",
    "./*": "./lib/*.js"
  },
  "files": [
    "lib"
  ],

I found an easy way to implemente a workaround. Hope it can help someone until Jest add support for this case. In my case, inside my package, I had globalHeaders.js with some named exports. So I was importing like this.

import {
  GLOBAL_HEADERS,
} from "@domain/package-name/globalHeaders";

but I got, can’t find module error. Since Jest does not supports “exports”: { “.”: “./lib/main.js”, “./": "./lib/.js” },

I try change my import to

import {
  GLOBAL_HEADERS,
} from "@domain/package-name/lib/globalHeaders";

It worked, but still far from elegant, so I also added this to my Jest config file

moduleNameMapper: {
    "^@domain/package-name/(.*)$": "@appscore/package-name/lib/$1",
  },

And now I can do this as it supposed to be from start

import {
  GLOBAL_HEADERS,
} from "@domain/package-name/globalHeaders";

[github-actions[bot]]

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