jest-resolve does not support requiring JSON files without an extension

[iffy]

Do you want to request a feature or report a bug? Bug

What is the current behavior? When I run jest, I get this error:

$ jest -c src/__tests__/jestconfig.json --no-cache
 FAIL  src/__tests__/test_foo.js
  ● Test suite failed to run

    Cannot find module '../package' from 'node-pre-gyp.js'

      at Resolver.resolveModule (node_modules/jest-resolve/build/index.js:179:17)
      at Object.<anonymous> (node_modules/sqlite3/node_modules/node-pre-gyp/lib/node-pre-gyp.js:60:17)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        0.753s
Ran all test suites.
^C

Steps to reproduce:

See this repo: https://github.com/iffy/sqlite-node-jest-bug

git clone https://github.com/iffy/sqlite-node-jest-bug
cd sqlite-node-jest-bug/
yarn
yarn test

What is the expected behavior? I expect sqlite to be found/required without error. I don't know enough about jest-require and node-pre-gyp to know which library has the error. I am able to use sqlite in my electron app (non-jest).

Please provide your exact Jest configuration and mention your Jest, node, yarn/npm version and operating system.

package.json:

{
  "dependencies": {
    "jest": "20.0.4",
    "sqlite3": "3.1.8"
  },
  "scripts": {
    "test": "jest -c src/__tests__/jestconfig.json"
  }
}

src/__tests__/jestconfig.json:

{
  "rootDir": "../../",
  "moduleFileExtensions": [
    "js"
  ],
  "testRegex": "test_.*\\.js$"
}

OS: macOS 10.12.4

$ yarn --version
0.24.6
$ node --version
v7.4.0
$ jest --version
v20.0.4

[iffy]

FWIW, if I change this line in jest-resolve/src/index.js from

const extensions = this._options.extensions.slice();

to

const extensions = this._options.extensions.slice().concat('.json');

I'm sure that's not the right place to support requiring .json, but that's the heart of the problem. Node's require supports loading .json files without an extension but jest-resolve doesn't.

[thymikee]

https://facebook.github.io/jest/docs/en/configuration.html#modulefileextensions-array-string

[iffy]

So you're saying I did this to myself :) Derp. Thank you!