public void Execute(CreateCategoryCommand command)
{
if (!command.Id.HasValue)
{
throw new ArgumentNullException("Id", "Category must have a id");
}
if (string.IsNullOrWhiteSpace(command.Name))
{
throw new ArgumentOutOfRangeException("Name", "Category must have a name");
}
if (persistence.FindByName(command.Name) != null)
{
throw new ArgumentException();
}
persistence.Create(new Category(id: command.Id.Value, name: command.Name));
}