'TypeError: Jest: a transform must export a `process` function jest

When running 'npm test' getting the following error:

 FAIL  __tests__/unit/domain/services/demo-service.ts
  ● Test suite failed to run

    TypeError: Jest: a transform must export a `process` function.

      at ScriptTransformer._getTransformer (node_modules/@jest/transform/build/ScriptTransformer.js:357:15)
      at ScriptTransformer.transformSource (node_modules/@jest/transform/build/ScriptTransformer.js:419:28)
      at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:523:40)
      at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)
typescriptnpmjestjs


Solution 1:[1]

ts-jest major version must match jest major version; e.g.

{
  "devDependencies": {
    "jest": "^26.4.2",
    "ts-jest": "^26.3.0"
  }
}

Solution 2:[2]

Might be the issue with the version of jest, I tried to use 26.5.5 which worked for me.

If you are using npm, there are some packages you could install:

npm install [email protected] --save-dev
npm install ts-jest --save-dev
npm install ts-node --save-dev
npm install ts-loader --save-dev

Solution 3:[3]

In my case, the config uses babel-jest + @babel/preset-typescript instead of ts-jest.

Therefore, I had to make sure babel-jest and jest had the same major version.

{
  "devDependencies": {
    "@babel/preset-typescript": "7.16.7",
    "babel-jest": "26.6.3",
    "jest": "26.6.3"
  }
}

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 bozdoz
Solution 2 Kobe24
Solution 3 Antony

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