Add correct yarn test:watchAll command in package.json, and remove unnecessary App.test.tsx

package.json

@@ -18,6 +18,7 @@
     "start": "react-scripts start",
     "build": "react-scripts build",
     "test": "react-scripts test",
+    "test:watchAll": "react-scripts test --watchAll",
     "eject": "react-scripts eject",
     "prettier": "prettier \"src/**/*.{js,jsx,ts,tsx,css,scss,md}\" --write",
     "format:check": "npm run prettier -- --check",

src/App.test.tsx

@@ -1,9 +0,0 @@
-import React from 'react';
-import { render, screen } from '@testing-library/react';
-import App from './App';
-
-test('renders learn react link', () => {
-  render(<App />);
-  const linkElement = screen.getByText(/learn react/i);
-  expect(linkElement).toBeInTheDocument();
-});