Require non-empty Argument of collection type

[Rast1234]

If i specify an Argument like this:

private readonly Argument<List<string>> inputArg = new("input", "Files to process");

I don't get any validation if the list is empty, as with single-token arguments. Right now i'm doing this to check for emptiness and print help to replicate default behavior which is not straightforward too:

private async Task<int> Handle(InvocationContext context, CancellationToken token)
    {
        var input = context.ParseResult.GetValueForArgument(inputArg);
        if (!input.Any())
        {
            var name = GetType().Name.ToLowerInvariant();
            await using var sw = new StringWriter();
            await sw.WriteLineAsync($"Required argument missing for command: '{name}'.\n");
            context.HelpBuilder.Write(this, sw);
            context.Console.Write(sw.ToString());
            return 0;
        }
        // rest of the handler
    }

• Is there a way to specify that collection-type argument should be not empty?
• Is there a way to trigger validation failure, simpler than HelpBuilder.Write?

[baronfel]

What happens if you set the Arity property on inputArg to ArgumentArity.OneOrMore?

[Rast1234]

Thanks, this works! Totally missed it. Was searching for something like "system.commandline list|collection not empty|required".

Anyway, any validation and help output tips? Maybe i missed something too