test(index): add tests for super string

index.test.js

@@ -1,4 +1,4 @@
-import { newFeature } from './index';
+import { newFeature, superString } from './index';
 
 test('should pass', () => {
   expect(3).toBe(3);
@@ -11,3 +11,7 @@ test('new Feature text', () => {
 test('extra new Feature text', () => {
   expect(typeof newFeature).toBe('string');
 });
+
+test('super string', () => {
+  expect(superString).toBe('this is a superb string');
+});