Update require to import for test files

test/unit/components/button.test.jsx

 /* eslint-env jest */
-const React = require('react'); // eslint-disable-line no-unused-vars
-const {shallow} = require('enzyme');
-const ButtonComponent = require('../../../src/components/button/button'); // eslint-disable-line no-unused-vars
-const renderer = require('react-test-renderer');
+import React from 'react'; // eslint-disable-line no-unused-vars
+import {shallow} from 'enzyme';
+import ButtonComponent from '../../../src/components/button/button'; // eslint-disable-line no-unused-vars
+import renderer from 'react-test-renderer';
 
 describe('ButtonComponent', () => {
     test('matches snapshot', () => {

test/unit/components/sprite-selector-item.test.jsx

 /* eslint-env jest */
-const React = require('react'); // eslint-disable-line no-unused-vars
-const {shallow} = require('enzyme');
-const SpriteSelectorItemComponent = require( // eslint-disable-line no-unused-vars
-    '../../../src/components/sprite-selector-item/sprite-selector-item');
-const CostumeCanvas = require( // eslint-disable-line no-unused-vars
-    '../../../src/components/costume-canvas/costume-canvas');
-const CloseButton = require('../../../src/components/close-button/close-button'); // eslint-disable-line no-unused-vars
-const renderer = require('react-test-renderer');
+import React from 'react'; // eslint-disable-line no-unused-vars
+import {shallow} from 'enzyme';
+// eslint-disable-next-line no-unused-vars
+import SpriteSelectorItemComponent from '../../../src/components/sprite-selector-item/sprite-selector-item';
+import CostumeCanvas from '../../../src/components/costume-canvas/costume-canvas';
+import CloseButton from '../../../src/components/close-button/close-button'; // eslint-disable-line no-unused-vars
+import renderer from 'react-test-renderer';
 
 describe('SpriteSelectorItemComponent', () => {
     let className;

test/unit/containers/green-flag.test.jsx

 /* eslint-env jest */
-const React = require('react'); // eslint-disable-line no-unused-vars
-const {shallow} = require('enzyme');
-const GreenFlag = require('../../../src/containers/green-flag'); // eslint-disable-line no-unused-vars
-const renderer = require('react-test-renderer');
-const VM = require('scratch-vm');
+import React from 'react'; // eslint-disable-line no-unused-vars
+import {shallow} from 'enzyme';
+import GreenFlag from '../../../src/containers/green-flag'; // eslint-disable-line no-unused-vars
+import renderer from 'react-test-renderer';
+import VM from 'scratch-vm';
 
 describe('GreenFlag Container', () => {
     let vm;

test/unit/containers/sprite-selector-item.test.jsx

 /* eslint-env jest */
-const React = require('react'); // eslint-disable-line no-unused-vars
-const {mount} = require('enzyme');
+import React from 'react'; // eslint-disable-line no-unused-vars
+import {mount} from 'enzyme';
 import configureStore from 'redux-mock-store';
 import {Provider} from 'react-redux'; // eslint-disable-line no-unused-vars
 
-const SpriteSelectorItem = require( // eslint-disable-line no-unused-vars
-    '../../../src/containers/sprite-selector-item');
-const CloseButton = require('../../../src/components/close-button/close-button'); // eslint-disable-line no-unused-vars
+import SpriteSelectorItem from '../../../src/containers/sprite-selector-item'; // eslint-disable-line no-unused-vars
+import CloseButton from '../../../src/components/close-button/close-button'; // eslint-disable-line no-unused-vars
 
 describe('SpriteSelectorItem Container', () => {
     const mockStore = configureStore();