Merge pull request #6128 from jonsequitur/fix-subcommand-help-regression

check for help in DotNetTopLevelCommandBase

src/dotnet/DotNetTopLevelCommandBase.cs

@@ -28,6 +28,8 @@ namespace Microsoft.DotNet.Cli
 
             ParseResult = parser.ParseFrom($"dotnet {CommandName}", args);
 
+            ParseResult.ShowHelpIfRequested();
+
             var subcommandName = ParseResult.Command().Name;
 
             try

src/dotnet/ParseResultExtensions.cs

@@ -13,6 +13,19 @@ namespace Microsoft.DotNet.Cli
             Console.WriteLine(parseResult.Command().HelpView());
 
         public static void ShowHelpOrErrorIfAppropriate(this ParseResult parseResult)
+        {
+            parseResult.ShowHelpIfRequested();
+
+            if (parseResult.Errors.Any())
+            {
+                throw new CommandParsingException(
+                    message: string.Join(Environment.NewLine,
+                                         parseResult.Errors.Select(e => e.Message)),
+                    helpText: parseResult?.Command()?.HelpView());
+            }
+        }
+
+        public static void ShowHelpIfRequested(this ParseResult parseResult)
         {
             var appliedCommand = parseResult.AppliedCommand();
 
@@ -23,14 +36,6 @@ namespace Microsoft.DotNet.Cli
                 // NOTE: this is a temporary stage in refactoring toward the ClicCommandLineParser being used at the CLI entry point. 
                 throw new HelpException(parseResult.Command().HelpView());
             }
-
-            if (parseResult.Errors.Any())
-            {
-                throw new CommandParsingException(
-                    message: string.Join(Environment.NewLine,
-                                parseResult.Errors.Select(e => e.Message)),
-                    helpText: parseResult?.Command()?.HelpView());
-            }
         }
     }
 }

test/dotnet.Tests/GivenThatTheUserRequestsHelp.cs

@@ -0,0 +1,44 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using FluentAssertions;
+using Microsoft.DotNet.Tools.Test.Utilities;
+using Xunit;
+
+namespace dotnet.Tests
+{
+    public class GivenThatTheUserRequestsHelp
+    {
+        [Theory]
+        [InlineData("-h")]
+        [InlineData("add -h")]
+        [InlineData("add package -h")]
+        [InlineData("add reference -h")]
+        [InlineData("build -h")]
+        [InlineData("cache -h")]
+        [InlineData("clean -h")]
+        [InlineData("list -h")]
+        [InlineData("migrate -h")]
+        [InlineData("msbuild -h")]
+        [InlineData("new -h")]
+        [InlineData("nuget -h")]
+        [InlineData("pack -h")]
+        [InlineData("publish -h")]
+        [InlineData("remove -h")]
+        [InlineData("restore -h")]
+        [InlineData("run -h")]
+        [InlineData("sln -h")]
+        [InlineData("sln add -h")]
+        [InlineData("sln list -h")]
+        [InlineData("sln remove -h")]
+        [InlineData("test -h")]
+        public void TheResponseIsNotAnError(string commandLine)
+        {
+            var result = new DotnetCommand()
+                .ExecuteWithCapturedOutput(commandLine);
+
+            result.ExitCode.Should().Be(0);
+        }
+    }
+}