[pixel shader]
float4 main() : SV_target
{
    float4 ret = float4(0.1, 0.2, 0.3, 0.4);
    ret.wyz.yx = float2(0.5, 0.6).yx;
    return ret;
}

[test]
draw quad
probe all rgba (0.1, 0.6, 0.3, 0.5)