[Refactor] Test: Create Setup File for Jest

Configure Jest with Enzyme and export shallow function globally.

Signed-off-by: Progyan Bhattacharya <[email protected]>

jest.setup.js

@@ -0,0 +1,7 @@
+import Adapter from 'enzyme-adapter-react-16';
+import { shallow, configure } from 'enzyme';
+import { SynchronousPromise } from 'synchronous-promise';
+
+configure({ adapter: new Adapter() });
+
+global.shallow = shallow;

package.json

@@ -39,5 +39,8 @@
   },
   "dependencies": {
     "@babel/runtime": "^7.4.3"
+  },
+  "jest": {
+    "setupFilesAfterEnv": [ "<rootDir>/jest.setup.js" ]
   }
 }

src/OptimisticToggle.test.js

@@ -1,13 +1,8 @@
 import React from 'react';
-import Adapter from 'enzyme-adapter-react-16';
-import { shallow, configure } from 'enzyme';
 import { SynchronousPromise } from 'synchronous-promise';
 
 import OptimisticToggle from './OptimisticToggle';
 
-configure({ adapter: new Adapter() });
-
-
 describe('Test <OptimisticToggle />', () => {
   /**
    * Ap: promiseA pending
@@ -18,6 +13,7 @@ describe('Test <OptimisticToggle />', () => {
    * x: checked
    */
   let wrapper, promise;
+
   beforeEach(() => {
     const action = () => {
       // promise will be overwritten everytime we simulate click

src/useOptimisticToggle.test.js

@@ -1,13 +1,8 @@
 import React from 'react';
-import Adapter from 'enzyme-adapter-react-16';
-import { shallow, configure } from 'enzyme';
 import { SynchronousPromise } from 'synchronous-promise';
 
 import useOptimisticToggle from './useOptimisticToggle';
 
-configure({ adapter: new Adapter() });
-
-
 describe('Test useOptimisticToggle()', () => {
   /**
    * Ap: promiseA pending
@@ -18,6 +13,7 @@ describe('Test useOptimisticToggle()', () => {
    * x: checked
    */
   let wrapper, promise;
+
   beforeEach(() => {
     const action = () => {
       // promise will be overwritten everytime we simulate click