From c5554b910415a868406e11da9b5f3dd11d08f2ef Mon Sep 17 00:00:00 2001
From: Sarah Oslund <sfoslund@microsoft.com>
Date: Tue, 6 Jul 2021 11:30:13 -0700
Subject: [PATCH] Show help on command parsing error

---
 .../CommandLineValidation/CommandParsingException.cs       | 7 ++++---
 src/Cli/dotnet/ParseResultExtensions.cs                    | 3 ++-
 src/Cli/dotnet/Program.cs                                  | 4 ++--
 .../dotnet-add-reference.Tests/GivenDotnetAddReference.cs  | 1 +
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/Cli/dotnet/CommandLineValidation/CommandParsingException.cs b/src/Cli/dotnet/CommandLineValidation/CommandParsingException.cs
index 7a7361055821..352468b4e576 100644
--- a/src/Cli/dotnet/CommandLineValidation/CommandParsingException.cs
+++ b/src/Cli/dotnet/CommandLineValidation/CommandParsingException.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System;
+using System.CommandLine.Parsing;
 
 namespace Microsoft.DotNet.Cli
 {
@@ -9,12 +10,12 @@ internal class CommandParsingException : Exception
     {
         public CommandParsingException(
             string message, 
-            string helpText = null) : base(message)
+            ParseResult parseResult = null) : base(message)
         {
-            HelpText = helpText ?? "";
+            ParseResult = parseResult;
             Data.Add("CLI_User_Displayed_Exception", true);
         }
 
-        public string HelpText { get; } = "";
+        public ParseResult ParseResult;
     }
 }
diff --git a/src/Cli/dotnet/ParseResultExtensions.cs b/src/Cli/dotnet/ParseResultExtensions.cs
index e3851bdac1ae..7292d9995461 100644
--- a/src/Cli/dotnet/ParseResultExtensions.cs
+++ b/src/Cli/dotnet/ParseResultExtensions.cs
@@ -26,7 +26,8 @@ public static void ShowHelpOrErrorIfAppropriate(this ParseResult parseResult)
                 {
                     throw new CommandParsingException(
                         message: string.Join(Environment.NewLine,
-                                             parseResult.Errors.Select(e => e.Message)));
+                                             parseResult.Errors.Select(e => e.Message)), 
+                        parseResult: parseResult);
                 }
             }
             else if (parseResult.HasOption("--help"))
diff --git a/src/Cli/dotnet/Program.cs b/src/Cli/dotnet/Program.cs
index eb8613a36728..b470461eb6eb 100644
--- a/src/Cli/dotnet/Program.cs
+++ b/src/Cli/dotnet/Program.cs
@@ -70,9 +70,9 @@ public static int Main(string[] args)
                         : e.Message.Red().Bold());
 
                     var commandParsingException = e as CommandParsingException;
-                    if (commandParsingException != null)
+                    if (commandParsingException != null && commandParsingException.ParseResult != null)
                     {
-                        Reporter.Output.WriteLine(commandParsingException.HelpText);
+                        commandParsingException.ParseResult.ShowHelp();
                     }
 
                     return 1;
diff --git a/src/Tests/dotnet-add-reference.Tests/GivenDotnetAddReference.cs b/src/Tests/dotnet-add-reference.Tests/GivenDotnetAddReference.cs
index 7cd4aaf58135..26141b5e0b3f 100644
--- a/src/Tests/dotnet-add-reference.Tests/GivenDotnetAddReference.cs
+++ b/src/Tests/dotnet-add-reference.Tests/GivenDotnetAddReference.cs
@@ -127,6 +127,7 @@ public void WhenNoCommandIsPassedItPrintsError(string commandName)
                 .Execute($"add", commandName);
             cmd.Should().Fail();
             cmd.StdErr.Should().Be(CommonLocalizableStrings.RequiredCommandNotPassed);
+            cmd.StdOut.Should().BeVisuallyEquivalentToIfNotLocalized(AddCommandHelpText(Directory.GetCurrentDirectory()));
         }
 
         [Fact]