export default function countVowels(str) {
  // TODO: Return how many vowels (a, e, i, o, u) are in the string
  throw new Error('Not implemented');
}

import countVowels from './countVowels';

describe('countVowels', () => {
  test('counts lowercase vowels', () => {
    expect(countVowels('hello')).toBe(2);
    expect(countVowels('rhythm')).toBe(0);
  });

  test('counts uppercase vowels', () => {
    expect(countVowels('AEIOU')).toBe(5);
  });

  test('counts vowels in mixed case and spaces', () => {
    expect(countVowels('A quick brown fox')).toBe(5);
  });

  test('handles empty string', () => {
    expect(countVowels('')).toBe(0);
  });
});