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

Question

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)

Answer 1

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

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

Answer 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