What is the difference between a unit test and a component test in a React app?

A unit test checks a small, isolated piece of logic, like a single function that formats a price, completely on its own. A component test renders an actual React component and checks that it behaves correctly, often simulating user interactions like clicks and typing, giving you confidence that the component works as a whole.

// Unit test, testing a plain function
test('formats price correctly', () => {
  expect(formatPrice(9.5)).toBe('$9.50');
});

// Component test, testing a full rendered component
test('shows formatted price', () => {
  render(<PriceTag amount={9.5} />);
  expect(screen.getByText('$9.50')).toBeInTheDocument();
});