public void ShouldThrowWhenParameterUsedIsNull()
{
_httpActionContext.ActionArguments.Add("dummy", null);
var attribute = new PreventCrossUserManipulationAttribute { UsersResource = _userResource.Object };
var result = Assert.Throws<HttpResponseException>(() => attribute.OnActionExecuting(_httpActionContext));
Assert.AreEqual(HttpStatusCode.InternalServerError, result.Response.StatusCode);
}