Add a test to ensure the rendering

Author: Duc Le

src/App.test.js

@@ -0,0 +1,9 @@
+import React from 'react';
+import { render } from '@testing-library/react';
+import Todo from './Todo';
+
+test('renders add todo input', () => {
+ const { getByPlaceholderText } = render(<Todo />);
+ const addTodoInputElement = getByPlaceholderText(/What needs to be done?/i);
+ expect(addTodoInputElement).toBeInTheDocument();
+});