Add test to count comments on a movie

__mocks__/commentsCount.js

@@ -0,0 +1,9 @@
+const comments = (commentList) => {
+  let counter;
+  commentList.forEach((comment, index) => {
+    counter = index + 1;
+  });
+  return counter;
+};
+
+export default comments;

commentsCount.test.js

@@ -0,0 +1,132 @@
+import comments from './__mocks__/commentsCount.js';
+
+const listOne = [
+  {
+    username: 'Jane',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Sam',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'John',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Ruth',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Mary',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'James',
+    comment: 'Nice movie',
+  },
+];
+
+const listTwo = [
+  {
+    username: 'John',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Ruth',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Mary',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'James',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Sam',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'John',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Ruth',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Mary',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Natasha',
+    comment: 'Nice movie',
+  },
+];
+
+const listThree = [
+  {
+    username: 'Jane',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Ruth',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Mary',
+    comment: 'Nice movie',
+  },
+];
+
+const listFour = [
+  {
+    username: 'Josh',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'John',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Ruth',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Mary',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'James',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Sam',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'John',
+    comment: 'Nice movie',
+  },
+  {
+    username: 'Ruth',
+    comment: 'Nice movie',
+  },
+];
+
+describe('Should test the number of comments on each movie', () => {
+  test('Test the number of comments', () => {
+    expect(comments(listOne)).toBe(6);
+  });
+  test('Test the number of comments', () => {
+    expect(comments(listTwo)).toBe(9);
+  });
+  test('Test the number of comments', () => {
+    expect(comments(listThree)).toBe(3);
+  });
+  test('Test the number of comments', () => {
+    expect(comments(listFour)).toBe(8);
+  });
+});