hsl(from rebeccapurple none none none)`,                         `rgb(0, 0, 0)`);
    test_valid_value(`color`, `hsl(from rebeccapurple none none none / none)`,                  `rgba(0, 0, 0, 0)`);
    test_valid_value(`color`, `hsl(from rebeccapurple h s none)`,                               `rgb(0, 0, 0)`);
    test_valid_value(`color`, `hsl(from rebeccapurple h s none / alpha)`,                       `rgb(0, 0, 0)`);
    test_valid_value(`color`, `hsl(from rebeccapurple h s l / none)`,                  