globalSetup doesn't process styleMocks / moduleNameMappers

🐛 Bug Report

globalSetup does not work with moduleNameMappers. In most setups this would be ok, but there are situations such as SSR where you want to setup a server once, you can run into issues with this.

Related to: https://github.com/facebook/jest/issues/5164

To Reproduce

• Set up a styleMock and a globalSetup file
• import a React component that imports a stylesheet in a globalSetup file

Expected behavior

globalSetup processes moduleNameMappers. The idea that globalSetup runs before “everything” is not practical. Setup will generally require some configuration options for things to work.

Run npx envinfo --preset jest

Paste the results here:

  System:
    OS: macOS Sierra 10.12.6
    CPU: x64 Intel(R) Core(TM) i7-3615QM CPU @ 2.30GHz
  Binaries:
    Node: 8.9.4 - ~/.nvm/versions/node/v8.9.4/bin/node
    Yarn: 1.5.1 - /usr/local/bin/yarn
    npm: 6.0.0 - /Users/Shared/java/projects/react/projects/mobile-minds/node_modules/.bin/npm
  npmPackages:
    jest: 22.4.3 => 22.4.3 

The workaround I currently use for both this issue and the related babel-transpile issue:

require('babel-register');
require('babel-polyfill');
['.css', '.eot', '.woff', '.ttf'].forEach(ext => {
  require.extensions[ext] = () => ({});
});

['.svg', '.png', '.jpg'].forEach(ext => {
  require.extensions[ext] = () => '';
});

[Akryum]

Here is a runnable reproduction of the bug:

https://codesandbox.io/s/boring-wilbur-ibkmj

Reproduction steps

1 - Un-comment globalSetup line in jest.config.js:

globalSetup: './tests/globalSetup.js'

2 - Run the following in the terminal:

yarn test

Error output:

Error: Cannot find module '@/utils'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:690:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (/sandbox/tests/globalSetup.js:3:5)
    at Module._compile (internal/modules/cjs/loader.js:776:30)
    at Module._compile (/sandbox/node_modules/pirates/lib/index.js:99:24)
    at Module._extensions..js (internal/modules/cjs/loader.js:787:10)
    at Object.newLoader [as .js] (/sandbox/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:653:32)

[wanton7]

I had to do my own monkey patching of require in globalSetup to make tsconfig “paths” work. I hope this code helps someone else. I run this code top of global setup JavaScript file. It doesn’t support all kinds of paths supported in tsconfig but works in cases we have.

const Mod = require('module');
const { compilerOptions } = require('../../tsconfig');
var path = require('path');

const currentDir = process.cwd();

const req = Mod.prototype.require;

Mod.prototype.require = function () {
  const modulePath = arguments[0];
  for (const fromPath of Object.keys(compilerOptions.paths)) {
    let toPath = compilerOptions.paths[fromPath][0];
    if (!fromPath || !fromPath.endsWith('/*') || !toPath || !toPath.endsWith('/*')) {
      throw Error('Only /* suffix supported');
    }
    if (!toPath.startsWith('./')) throw Error('Only destination prefix ./ supported');

    if (modulePath.startsWith(fromPath.slice(0, -1))) {
      arguments[0] = path.join(currentDir, toPath.slice(2, -1), modulePath.slice(fromPath.length - 1));
    }
  }

  return req.apply(this, arguments);
};