, `oklch(from oklch(0.7 0.45 30 / 40%) 0.5 1.2 400deg / 500)`, `oklch(0.5 1.2 40)`);
    test_valid_value(`color`, `oklch(from oklch(0.7 0.45 30 / 40%) 0.5 1.2 -400deg / -500)`, `oklch(0.5 1.2 320 / 0)`);

    // Testing valid permutation (types match).
    // NOTE: 'c' is a vaild hue, as hue is <angle>|<number>.
    test_valid_value(`color`, `oklch(from oklch(.7 0.45 30) l c c / alpha)`, `oklch(0.7 0.45 0.45)`);
    test_valid_value(`color`, `oklch(from oklch(.7 0.45 30 / 40%) l c c / alpha)`, `oklch(0.7 0