)`);
    test_valid_value(`color`, `oklch(from oklch(0.7 0.45 30 / 40%) l c none / alpha)`,                           `oklch(0.7 0.45 none / 0.4)`);
    test_valid_value(`color`, `oklch(from oklch(0.7 0.45 30 / 40%) l c h / none)`,                               `oklch(0.7 0.45 30 / none)`);
    // FIXME: Clarify with spec editors if 'none' should pass through to the constants.
    test_valid_value(`color`, `oklch(from oklch(none none none) l c h)`,                                       `oklch(0 0 0)`);
    