r(display-p3 0 0 0) l c h / alpha)`, `oklch(0 0 0)`);
    // TODO: redo conversion with oklab(0.7 0.45 0.3)
    test_valid_value(`color`, `oklch(from oklab(0.7 45 30) l c h / alpha)`, `oklch(0.7 54.08327 33.690067)`);

    // Testing replacement with 0.
    test_valid_value(`color`, `oklch(from oklch(0.7 0.45 30) 0 0 0)`, `oklch(0 0 0)`);
    test_valid_value(`color`, `oklch(from oklch(0.7 0.45 30) 0 0 0deg)`, `oklch(0 0 0)`);
    test_valid_value(`color`, `oklch(from oklch(0.7 0.45 30) 0 0 0 / 0)`, `oklch(