TypeError: Jest: a transform must export a process function. (upgrading from 26.5.6 to 27.0.2)

[danbee]

Dependabot has opened a PR to upgrade ts-jest for us, from 26.5.6 to 27.0.2 and all our front end tests are currently failing with the following error message:

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

      at ScriptTransformer._getTransformer (node_modules/@jest/transform/build/ScriptTransformer.js:360:13)
      at ScriptTransformer.transformSource (node_modules/@jest/transform/build/ScriptTransformer.js:427:28)
      at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:569:40)
      at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:607:25)

I'm not sufficiently familiar with Jest and ts-jest to be able to diagnose this, and searching the Internet has not turned up anything useful so far. Has anybody seen this before, or can give me some pointers on where to start looking?

Our Jest config looks like this:

{
  "configs": [
    {
      "automock": false,
      "cache": true,
      "cacheDirectory": "/private/var/folders/n7/qd07sw750nb5107xy97ftt880000gn/T/jest_dx",
      "clearMocks": true,
      "coveragePathIgnorePatterns": [
        "/node_modules/"
      ],
      "cwd": "/Volumes/Projects/BuoyRails",
      "detectLeaks": false,
      "detectOpenHandles": false,
      "errorOnDeprecated": false,
      "extraGlobals": [],
      "forceCoverageMatch": [],
      "globals": {
        "ts-jest": {
          "tsconfig": "spec/javascript/tsconfig.json"
        }
      },
      "haste": {
        "computeSha1": false,
        "throwOnModuleCollision": false
      },
      "injectGlobals": true,
      "moduleDirectories": [
        "app/javascript",
        "node_modules",
        "spec/javascript"
      ],
      "moduleFileExtensions": [
        "js",
        "json",
        "jsx",
        "ts",
        "tsx",
        "node"
      ],
      "moduleNameMapper": [
        [
          "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$",
          "/Volumes/Projects/BuoyRails/spec/javascript/__mocks__/fileMock.ts"
        ]
      ],
      "modulePathIgnorePatterns": [],
      "name": "b9a7b608a34caa040a8e1f9f1e8c3f4b",
      "prettierPath": "prettier",
      "resetMocks": false,
      "resetModules": false,
      "restoreMocks": true,
      "rootDir": "/Volumes/Projects/BuoyRails",
      "roots": [
        "/Volumes/Projects/BuoyRails/spec/javascript"
      ],
      "runner": "jest-runner",
      "setupFiles": [
        "/Volumes/Projects/BuoyRails/node_modules/jest-plugin-context/setup.js"
      ],
      "setupFilesAfterEnv": [
        "/Volumes/Projects/BuoyRails/jest.setup.ts"
      ],
      "skipFilter": false,
      "slowTestThreshold": 5,
      "snapshotSerializers": [],
      "testEnvironment": "/Volumes/Projects/BuoyRails/node_modules/jest-environment-jsdom/build/index.js",
      "testEnvironmentOptions": {},
      "testLocationInResults": false,
      "testMatch": [
        "**/__tests__/**/*.[jt]s?(x)",
        "**/?(*.)+(spec|test).[tj]s?(x)"
      ],
      "testPathIgnorePatterns": [
        "/node_modules/"
      ],
      "testRegex": [],
      "testRunner": "/Volumes/Projects/BuoyRails/node_modules/jest-jasmine2/build/index.js",
      "testURL": "http://localhost",
      "timers": "real",
      "transform": [
        [
          "^.+\\.[tj]sx?$",
          "/Volumes/Projects/BuoyRails/node_modules/ts-jest/dist/index.js",
          {}
        ]
      ],
      "transformIgnorePatterns": [
        "/node_modules/",
        "\\.pnp\\.[^\\/]+$"
      ],
      "watchPathIgnorePatterns": []
    }
  ],
  "globalConfig": {
    "bail": 0,
    "changedFilesWithAncestor": false,
    "collectCoverage": false,
    "collectCoverageFrom": [],
    "coverageDirectory": "/Volumes/Projects/BuoyRails/coverage",
    "coverageProvider": "babel",
    "coverageReporters": [
      "json",
      "text",
      "lcov",
      "clover"
    ],
    "detectLeaks": false,
    "detectOpenHandles": false,
    "errorOnDeprecated": false,
    "expand": false,
    "findRelatedTests": false,
    "forceExit": false,
    "json": false,
    "lastCommit": false,
    "listTests": false,
    "logHeapUsage": false,
    "maxConcurrency": 5,
    "maxWorkers": 15,
    "noStackTrace": false,
    "nonFlagArgs": [],
    "notify": false,
    "notifyMode": "failure-change",
    "onlyChanged": false,
    "onlyFailures": false,
    "passWithNoTests": false,
    "projects": [],
    "rootDir": "/Volumes/Projects/BuoyRails",
    "runTestsByPath": false,
    "skipFilter": false,
    "testFailureExitCode": 1,
    "testPathPattern": "",
    "testSequencer": "/Volumes/Projects/BuoyRails/node_modules/@jest/test-sequencer/build/index.js",
    "updateSnapshot": "new",
    "useStderr": false,
    "watch": false,
    "watchAll": false,
    "watchman": true
  },
  "version": "26.6.3"
}

[ahnpnl]

ts-jest 27 goes with jest 27, you can check related discussion here #2612

[danbee]

Thanks! I didn't know that... 🤦🏼

[DaYesahh]

thanks so much! I fixed this problem by this way!

[imzubair10]

worked for me too, thanks!