Enable react linting and move test file to .jsx instead of .js.

package.json

@@ -140,7 +140,6 @@
     "setupFiles": [
       "<rootDir>/test/helpers/enzyme-setup.js"
     ],
-
     "moduleNameMapper": {
       "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/test/__mocks__/fileMock.js",
       "\\.(css|less|scss)$": "<rootDir>/test/__mocks__/styleMock.js"

test/.eslintrc.js

@@ -1,4 +1,5 @@
 module.exports = {
+    extends: ['scratch/react'],
     env: {
         jest: true
     }