alue(`color`, `oklch(from oklch(2 3 400 / 500%) l c h / alpha)`, `oklch(1 3 40)`);
    test_valid_value(`color`, `oklch(from oklch(-2 -3 -400 / -500%) l c h / alpha)`, `oklch(0 0 320 / 0)`);

    // Test nesting relative colors.
    test_valid_value(`color`, `oklch(from oklch(from oklch(0.7 0.45 30) l c h) l c h)`, `oklch(0.7 0.45 30)`);

    // Testing non-sRGB origin colors (no gamut mapping will happen since the destination is not a bounded RGB color space).
    test_valid_value(`color`, `oklch(from colo