Enable src/node_modules

Created by: modernserf

[HOLD] not particularly useful without changes in Jest

Partially fixes https://github.com/facebookincubator/create-react-app/issues/607

These are the necessary changes in react-scripts to allow code to live in src/node_modules and allow Jest to run tests in that directory.

However, Jest cannot find these tests on its own -- all files in any node_modules are filtered out even before the file matching patterns are applied. See issue https://github.com/facebook/jest/issues/2145.

Without changes in Jest, there are a few workarounds:

Import the package tests into a file that jest can find

// src/node_modules/Foo/Foo.test.js
it("does a thing", ()=> {
  expect(true).toBe(true)
})

// src/index.js
import "Foo/Foo.test.js"

Whitelist the directories you want to test with the haste.providesModuleNodeModules option

This is not the intended use for this option, but its used as a whitelist for the haste module resolution, and therefore Jest can find tests in these directories.

TODO

• get related issue in facebook/jest resolved
• figure out how to test this
• rebase, clean up etc

packages/react-scripts/template/gitignore

 # See http://help.github.com/ignore-files/ for more about ignoring files.
 
 # dependencies
-node_modules
+/node_modules
 
 # testing
 coverage

packages/react-scripts/utils/createJestConfig.js

@@ -28,6 +28,10 @@ module.exports = (resolve, rootDir, isEjecting) => {
     setupTestFrameworkScriptFile: setupTestsFile,
     testPathIgnorePatterns: ['<rootDir>/(build|docs|node_modules)/'],
     testEnvironment: 'node',
+    preprocessorIgnorePatterns: ["<rootDir>/node_modules"],
+    haste: {
+        providesModuleNodeModules: [".*"],
+    },
   };
   if (rootDir) {
     config.rootDir = rootDir;