one none) h w b)`,                            `rgb(255, 0, 0)`);
    test_valid_value(`color`, `hwb(from hwb(none none none / none) h w b / alpha)`,             `rgba(255, 0, 0, 0)`);
    test_valid_value(`color`, `hwb(from hwb(120deg none 50% / .5) h w b)`,                      `rgba(0, 128, 0, 0.5)`);
    test_valid_value(`color`, `hwb(from hwb(120deg 20% 50% / none) h w b / alpha)`,             `rgba(51, 128, 51, 0)`);
    test_valid_value(`color`, `hwb(from hwb(none 20% 50% / .5) h w b / alpha)`,       