import pytest

class TestFunction:
    def test_valid_input_returns_expected(self):
        assert function("valid") == "expected"
    
    def test_empty_input_returns_empty(self):
        assert function("") == ""
    
    def test_invalid_raises_error(self):
        with pytest.raises(ValueError):
            function(None)

describe('function', () => {
  it('returns expected for valid input', () => {
    expect(fn('valid')).toBe('expected');
  });

  it('handles empty input', () => {
    expect(fn('')).toBe('');
  });

  it('throws for invalid', () => {
    expect(() => fn(null)).toThrow();
  });
});

test_[what]_[condition]_[expected]

test_login_valid_credentials_returns_token
test_login_wrong_password_raises_error