         `rgba(102, 51, 153, 0)`);
    test_valid_value(`color`, `hsl(from rebeccapurple none s l / alpha)`,                       `rgb(153, 51, 51)`);
    test_valid_value(`color`, `hsl(from hsl(120deg 20% 50% / .5) h s none / alpha)`,            `rgba(0, 0, 0, 0.5)`);
    test_valid_value(`color`, `hsl(from hsl(120deg 20% 50% / .5) h s l / none)`,                `rgba(102, 153, 102, 0)`);
    test_valid_value(`color`, `hsl(from hsl(120deg 20% 50% / .5) none s l / alpha)`,            `rgba(153, 102, 102, 0