Importing json files result in SyntaxError: Unexpected token m in JSON at position 0

💥 Regression Report

After upgrade of jest-runtime to 24.8.0 the json file import stopped working because the json file is not imported but transformed into following string

module.exports = "permanentComponentConfigurations.json";

As a workaround I provided a json transformation like so

package.json

    "transform": {
      ".+\\.(js|jsx|ts|tsx)$": "<rootDir>/node_modules/babel-jest",
      ".+\\.css$": "<rootDir>/config/jest/cssTransform.js",
      ".+\\.json": "<rootDir>/config/jest/jsonTransform.js",
      "(?!.*\\.(js|jsx|ts|tsx|css|json)$)": "<rootDir>/config/jest/fileTransform.js"
    },

(The configuration from package.json is based on Create-React-App)

jsonTransform.js

module.exports = {
  process(src) {
    return src;
  }
};

Last working version

Worked up to version: 24.7.1

Stopped working in version: 24.8.0

To Reproduce

Import a json file in js like

import PERMANENT_CONFIGURATIONS from 'core/service/config/permanentComponentConfigurations.json';

With 24.8.0 json files are transformed as well. But the resulting json file import results to following content

module.exports = "permanentComponentConfigurations.json";

Expected behavior

The imported json file should be JSON.parsed like before with 24.7.1 per default. If someone needs custom transformation, providing a transformation file is fine, but it should not be a requirement.

Link to repl or repo (highly encouraged)

Please provide either a repl.it demo or a minimal repository on GitHub.

Issues without a reproduction link are likely to stall.

Run npx envinfo --preset jest

  System:
    OS: Windows 10
    CPU: (4) x64 Intel(R) Xeon(R) CPU E3-1226 v3 @ 3.30GHz
  Binaries:
    Node: 10.15.3 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.15.2 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 6.4.1 - C:\Program Files\nodejs\npm.CMD

[sakulstra]

just a small addition for people accidentally stepping over this:

if you’ve been using

transform: {
    ...,
    '*.': 'babel-jest'
}

28.8 was a breaking change as it will break your json imports. You might want to e.g. restrict the transform to only transform js files.

transform: {
   ...,
    '^.+\\.(js)$': 'babel-jest'
}

[FlaviooLima]

@sakulstra After 3 hours of debugging, I must say… You saved my day! I’m almost in tears !!!