The return value from Option actions is discarded #2772

using System.CommandLine;
using System.CommandLine.Invocation;

namespace CommandLineTest
{
    [TestClass]
    public sealed class CommandLineTests
    {
        [TestMethod]
        public void OptionActionReturnValuePropagates()
        {
            RootCommand root = new("CommandLine Test");

            Option<bool> option = new("--arg");
            option.Action = new CustomAction(_ => 42);
            root.Options.Add(option);
            root.SetAction(r => { });

            ParseResult parsedArgs = root.Parse(["--arg"]);
            int result = parsedArgs.Invoke();

            Assert.AreEqual(42, result);
        }

        class CustomAction : SynchronousCommandLineAction
        {
            private readonly Func<ParseResult, int> _callback;

            internal CustomAction(Func<ParseResult, int> callback) => _callback = callback;
            public override int Invoke(ParseResult parseResult) => _callback(parseResult);
            public override bool Terminating => false;
        }
    }
}