ts-jest: After upgrading to ts-jest 27: SyntaxError: Cannot use import statement outside a module

I was getting this error, but not using next/babel. I managed to get my tests to work with this config:

/** @type {import('@ts-jest/dist/types').InitialOptionsTsJest} */
module.exports = {
  preset: "ts-jest",
  testEnvironment: "node",
  globals: {
    "ts-jest": {
      isolatedModules: true,
    },
  },
  transform: {
    "^.+\\.jsx?$": "babel-jest",
  },
  moduleNameMapper: {

  },
  moduleDirectories: ["js", ".", "node_modules"],
}

In my case jest would stumle on .js files from one of the dependencies in node_modules with SyntaxError: Cannot use import statement outside a module.

I had to make sure, that ts-jest wouldn’t ignore (when transforming) .js files in troublesome dependency.

After reading carefully about presets, I realized, that it leaves them ‘as-is’ with preset: 'ts-jest'. I changed it to preset: 'ts-jest/presets/js-with-ts' and set "allowJs": true in tsconfig.json.

To not mess up my project’s tsconfig.json, I have a separate one for jest.

In the end, my jest.config.js looks mainly like this:

module.exports = {
	preset: 'ts-jest/presets/js-with-ts',
	testEnvironment: "node",
	globals: {
		'ts-jest': {
			tsconfig: '<rootDir>/test/tsconfig.json',
		},
	},
	transformIgnorePatterns: [
		"node_modules/(?!troublesome-dependency/.*)",
	],
}

P.S. I didn’t need a transform field, since the preset is already on it.

P.P.S. I didn’t need to introduce any babel configuration

This should be fixed already, you can try clearing jest cache.

Adding

  globals: {
    'ts-jest': {
      isolatedModules: true,
    },
  },

works.

My setup:

jest.config.js

/* eslint-disable unicorn/prefer-module */
/** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */
module.exports = {
  preset: 'ts-jest',
  transform: {
    '\\.[jt]sx?$': 'ts-jest',
  },
  testEnvironment: 'node',
  setupFilesAfterEnv: ['./test/jest.setup.ts'],
  extensionsToTreatAsEsm: ['.ts'],
  globals: {
    'ts-jest': {
      useESM: true,
      isolatedModules: true,
    },
  },
};

package.json

  "scripts": {
    "test": "NODE_OPTIONS=--experimental-vm-modules jest --config=jest.config.js",

Before the change, I get lots of error, or just hang there stops running:

 FAIL  test/wikiast-util-to-wikitext.test.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:

    slate-write/node_modules/unist-util-parents/index.js:16
    export function parents(tree) {
    ^^^^^^

    SyntaxError: Unexpected token 'export'

      1 | import cloneDeep from 'lodash/cloneDeep';
      2 | import type { IParseTreeNode } from 'tiddlywiki';
    > 3 | import { parents } from 'unist-util-parents';

And now "ts-jest": "28.0.2", works very well.

UPDATED

ts-jest doesn’t understand the tsconfig compilerOptions setting for jsx of “preserve”, but this is required for next. Therefore the best thing to do is override it just for jest in your jest config:

module.exports = {
  globals: {
    // This is necessary because next.js forces { "jsx": "preserve" }, but ts-jest requires { "jsx": "react-jsx" }
    'ts-jest': {
      tsconfig: {
        jsx: 'react-jsx',
      },
    },
  },
  //...
};

For me what works;

module.exports = {
  preset: "ts-jest/presets/default-esm",
  testEnvironment: "node",
  extensionsToTreatAsEsm: [".ts"],
};

And run with; "test": "NODE_OPTIONS=--experimental-vm-modules jest",

No other changes to the default installation, thanks @linonetwo

@JeanJPNM This one works for me:

jest.config.json

{
  "preset": "ts-jest",
  "testEnvironment": "jsdom",
  "moduleFileExtensions": ["ts", "tsx", "js", "jsx", "json", "node"],
  "roots": [
    "src"
  ],
  "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(tsx)$",
  "transform": {
    "^.+\\.tsx$": "ts-jest"
  },
  "moduleNameMapper": {
    "src/(.*)": "<rootDir>/src/$1"
  }
}

package.json

{
  // ...
  "devDependencies": {
   "@types/jest": "^27.4.0",
    "jest": "^27.5.1",
    "ts-jest": "^27.1.3",
    // ...
  }
}

same issue here, an simple ts project without babel with default config

module.exports = {
    preset: 'ts-jest',
    testEnvironment: 'node',
};

the error

SyntaxError: Cannot use import statement outside a module