Why Jest failing on node-fetch giving syntax error on import

Question

I'm trying to understand how to fix the following error using Jest in my unit tests in NodeJS.

The test run with this command "test": "NODE_ENV=test jest spec/* -i --coverage --passWithNoTests",

I'm also using babel and this is my config

{
  "presets": [["@babel/env", { "targets": { "node": "current" } }]],
  "plugins": [
    "@babel/plugin-syntax-dynamic-import",
    ["babel-plugin-inline-import", { "extensions": [".gql"] }],
    ["@babel/plugin-proposal-decorators", { "legacy": true }]
  ]
}

In package.json I have this

"jest": {
    "verbose": true,
    "collectCoverageFrom": [
      "spec/**/*.js"
    ]
  },

I tried several guides online but cannot find a solution to this

Add `"type": "module"` to `package.json`. – code Mar 08 '22 at 21:45 — code, Mar 08 '22 at 21:45
This not working already tried same error happen – Jakub Mar 08 '22 at 21:48 — Jakub, Mar 08 '22 at 21:48
Is the code being executed on browser or Node? – code Mar 08 '22 at 21:52 — code, Mar 08 '22 at 21:52
What version of Node are you using? – code Mar 08 '22 at 21:52 — code, Mar 08 '22 at 21:52
This is NodeJS and the version is ~14.17.6 – Jakub Mar 08 '22 at 22:41 — Jakub, Mar 08 '22 at 22:41

score 0 · Answer 1 · answered Nov 06 '22 at 21:58

You've got Jest successfully configured to transform your code, but it is not transforming modules that you're importing—in this case node-fetch, which has the import keyword in its source code (as seen in your error). This is because, by default, Jest is configured not to transform files in node_modules:

transformIgnorePatterns [array]

Default: ["/node_modules/", "\.pnp\.[^\/]+$"]

An array of regexp pattern strings that are matched against all source file paths before transformation. If the file path matches any of the patterns, it will not be transformed.

You can set transformIgnorePatterns to exclude certain packages in node_modules with a jest.config.js like this:

const esModules = [
  'node-fetch',
  'data-uri-to-buffer',
  'fetch-blob',
  'formdata-polyfill',
].join('|');

module.exports = {
  transformIgnorePatterns: [
    `/node_modules/(?!${esModules})`,
    '\\.pnp\\.[^\\/]+$',
  ],
};

(see https://github.com/nrwl/nx/issues/812#issuecomment-429420861)

score -1 · Answer 2 · answered Mar 08 '22 at 23:36

-1

If you have .babelrc try to rename it to babel.config.js

Source: https://babeljs.io/docs/en/configuration#whats-your-use-case

but also this (there's more in the discussion) Jest won't transform the module - SyntaxError: Cannot use import statement outside a module

answered Mar 08 '22 at 23:36

Gianluigi Trontini

1

The problem is that the error is inside the node-fetch as you see the screenshot is regarding inside the module – Jakub Mar 09 '22 at 10:32
I read that by renaming it (if you didn't already), Babel will parse also the node_modules folder – Gianluigi Trontini Mar 10 '22 at 11:04

Why Jest failing on node-fetch giving syntax error on import

2 Answers2