Adds JSX extension support (#563)

* Adds JSX extension support

* PR changes

* Add testRegex

* Add note about not recommending JSX, link to issue

scripts/utils/createJestConfig.js

@@ -19,6 +19,7 @@ module.exports = (resolve, rootDir) => {
   }
 
   const config = {
+    moduleFileExtensions: ['jsx', 'js', 'json'],
     moduleNameMapper: {
       '^[./a-zA-Z0-9$_-]+\\.(jpg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm)$': resolve('config/jest/FileStub.js'),
       '^[./a-zA-Z0-9$_-]+\\.css$': resolve('config/jest/CSSStub.js')
@@ -26,7 +27,8 @@ module.exports = (resolve, rootDir) => {
     scriptPreprocessor: resolve('config/jest/transform.js'),
     setupFiles: setupFiles,
     testPathIgnorePatterns: ['<rootDir>/(build|docs|node_modules)/'],
-    testEnvironment: 'node'
+    testEnvironment: 'node',
+    testRegex: '(/__tests__/.*|\\.(test|spec))\\.(js|jsx)$',
   };
   if (rootDir) {
     config.rootDir = rootDir;