Show ArgumentHelpName in help if explicitly set by user

Author: sfoslund

src/System.CommandLine.Tests/Help/HelpBuilderTests.Approval.cs

@@ -53,12 +53,10 @@ public void Help_describes_default_values_for_complex_root_command_scenario()
                 new Option<FileAccess>(aliases: new string[] {"--the-root-option-enum-arg", "-troea"}, () => FileAccess.Read) 
                 {
                     Description = "the-root-option-description",
-                    ArgumentHelpName = "the-root-option-arg",
                 },
                 new Option<FileAccess>(aliases: new string[] {"--the-root-option-required-enum-arg", "-trorea"}, () => FileAccess.Read) 
                 {
                     Description = "the-root-option-description",
-                    ArgumentHelpName = "the-root-option-arg",
                     IsRequired = true
                 },
                 new Option(aliases: new string[] {"--the-root-option-multi-line-description", "-tromld"}) {

src/System.CommandLine.Tests/Help/HelpBuilderTests.cs

@@ -469,6 +469,32 @@ public void Arguments_section_includes_configured_argument_aliases()
             help.Should().Contain("Sets the verbosity.");
         }
 
+
+        private enum VerbosityOptions
+        {
+            q,
+            m,
+            n,
+            d,
+        }
+
+        [Fact]
+        public void Arguments_section_uses_name_over_suggestions_if_specified()
+        {
+            var command = new Command("the-command")
+            {
+                new Option<VerbosityOptions>(new[] { "-v", "--verbosity" })
+                {
+                    ArgumentHelpName = "LEVEL"
+                }
+            };
+
+            _helpBuilder.Write(command);
+
+            var help = _console.Out.ToString();
+            help.Should().Contain("-v, --verbosity <LEVEL>");
+        }
+
         [Fact]
         public void Arguments_section_uses_description_if_provided()
         {
@@ -1240,7 +1266,7 @@ public void Help_describes_default_value_for_option_with_argument_having_default
 
             help.Should().Contain($"[default: the-arg-value]");
         }
-
+        
         [Fact]
         public void Option_arguments_with_default_values_that_are_enumerable_display_pipe_delimited_list()
         {

src/System.CommandLine/Argument.cs

@@ -17,6 +17,7 @@ public class Argument : Symbol, IArgument
     {
         private Func<ArgumentResult, object?>? _defaultValueFactory;
         private IArgumentArity? _arity;
+        private bool _isHelpNameSpecified;
         private TryConvertArgument? _convertArguments;
         private Type _argumentType = typeof(string);
         private SuggestionSourceList? _suggestions = null;
@@ -65,6 +66,16 @@ public IArgumentArity? Arity
             set => _arity = value;
         }
 
+
+        /// <summary>
+        /// Gets or sets if the ArgumentHelpName is specified by the user.
+        /// </summary>
+        public bool IsHelpNameSpecified
+        {
+            get => _isHelpNameSpecified;
+            set => _isHelpNameSpecified = value;
+        }
+
         internal TryConvertArgument? ConvertArguments
         {
             get

src/System.CommandLine/Help/HelpBuilder.cs

@@ -522,7 +522,7 @@ protected string GetArgumentDescriptor(IArgument argument)
 
             string descriptor;
             var suggestions = argument.GetSuggestions().ToArray();
-            if (suggestions.Length > 0)
+            if (suggestions.Length > 0 && UseSuggestionsInHelp(argument))
             {
                 descriptor = string.Join("|", suggestions);
             }
@@ -538,6 +538,12 @@ protected string GetArgumentDescriptor(IArgument argument)
             return descriptor;
         }
 
+        private bool UseSuggestionsInHelp(IArgument argument)
+        {
+            var arg = argument as Argument;
+            return arg == null || !arg.IsHelpNameSpecified;
+        }
+
         private class Customization
         {
             public Customization(Func<string?>? getDescriptor,

src/System.CommandLine/Option.cs

@@ -134,7 +134,11 @@ internal virtual Argument Argument
         public string ArgumentHelpName
         {
             get => Argument.Name;
-            set => Argument.Name = value;
+            set
+            {
+                Argument.Name = value;
+                Argument.IsHelpNameSpecified = true;
+            }
         }
 
         /// <summary>