Omit empty description from help output

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

@@ -466,7 +466,6 @@ public void Help_default_sections_can_be_wrapped()
             command.Parse("test -h").Invoke(new() { Output = output });
 
             output.ToString().Should().Be(
-                $"Description:{NewLine}{NewLine}" +
                 $"Usage:{NewLine}  test [options]{NewLine}{NewLine}" +
                 $"Options:{NewLine}" +
                 $"  --option   option {NewLine}" +
@@ -534,4 +533,4 @@ private string GetDefaultHelp(Command command, bool trimOneNewline = true)
             return output;
         }
     }
-}
+}

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

@@ -74,6 +74,21 @@ public void Synopsis_section_properly_wraps_description()
             _console.ToString().Should().Contain(expected);
         }
 
+        [Theory]
+        [InlineData(null)]
+        [InlineData("")]
+        [InlineData(" ")]
+        public void Synopsis_section_is_omitted_when_description_is_missing(string? description)
+        {
+            var command = new RootCommand(description);
+
+            _helpBuilder.Write(command, _console);
+
+            _console.ToString().Should()
+                .NotContain(LocalizationResources.HelpDescriptionTitle())
+                .And.Contain(LocalizationResources.HelpUsageTitle());
+        }
+
         [Fact]
         public void Command_name_in_synopsis_can_be_specified()
         {

src/System.CommandLine.Tests/HelpOptionTests.cs

@@ -57,7 +57,7 @@ public async Task Help_option_interrupts_execution_of_the_specified_command()
     [InlineData("/?")]
     public async Task Help_option_accepts_default_values(string value)
     {
-        var command = new Command("command")
+        var command = new Command("command", "command description")
         {
             new HelpOption()
         };
@@ -72,7 +72,7 @@ public async Task Help_option_accepts_default_values(string value)
     [Fact]
     public async Task Help_option_does_not_display_when_option_defined_with_same_alias()
     {
-        var command = new Command("command");
+        var command = new Command("command", "command description");
         command.Options.Add(new Option<bool>("-h"));
 
         var output = new StringWriter();
@@ -143,7 +143,7 @@ public void There_are_no_parse_errors_when_help_is_invoked_on_a_command_with_req
     [InlineData("--confused")]
     public async Task HelpOption_with_custom_aliases_uses_aliases(string helpAlias)
     {
-        RootCommand command = new()
+        RootCommand command = new("root description")
         {
             new HelpOption("/lost", "--confused")
         };
@@ -385,4 +385,4 @@ public override int Invoke(ParseResult parseResult)
             return 0;
         }
     }
-}
+}

src/System.CommandLine.Tests/ParseErrorReportingTests.cs

@@ -17,7 +17,7 @@ public class ParseErrorReportingTests
     [Fact] // https://github.com/dotnet/command-line-api/issues/817
     public void Help_is_shown_when_required_subcommand_is_missing()
     {
-        var root = new RootCommand
+        var root = new RootCommand("root description")
         {
             new Command("inner"),
             new HelpOption()
@@ -37,7 +37,7 @@ public void Help_is_shown_when_required_subcommand_is_missing()
     [Fact]
     public void Help_display_can_be_disabled()
     {
-        RootCommand rootCommand = new()
+        RootCommand rootCommand = new("root description")
         {
             new Option<bool>("--verbose")
         };
@@ -104,7 +104,7 @@ public async Task When_there_are_parse_errors_then_customized_help_action_on_anc
     [Fact]
     public void When_no_help_option_is_present_then_help_is_not_shown_for_parse_errors()
     {
-        RootCommand rootCommand = new();
+        RootCommand rootCommand = new("root description");
         rootCommand.Options.Clear();
         var output = new StringWriter();
 
@@ -172,4 +172,4 @@ public void Pre_actions_cannot_clear_parse_errors()
 
         result.Errors.Should().NotBeEmpty();
     }
-}
+}

src/System.CommandLine.Tests/Utility/AssertionExtensions.cs

@@ -46,9 +46,9 @@ public static AndConstraint<StringCollectionAssertions<IEnumerable<string>>> BeE
         return assertions.BeEquivalentTo(expectedValues, c => c.WithStrictOrderingFor(s => s));
     }
 
-    public static AndConstraint<StringAssertions> ShowHelp(this StringAssertions output) => 
+    public static AndConstraint<StringAssertions> ShowHelp(this StringAssertions output) =>
         output.Subject.Should().Match("*Description:*Usage:*");
 
-    public static AndConstraint<StringAssertions> NotShowHelp(this StringAssertions output) => 
+    public static AndConstraint<StringAssertions> NotShowHelp(this StringAssertions output) =>
         output.Subject.Should().NotMatch("*Description:*Usage:*");
-}
+}

src/System.CommandLine/Help/HelpBuilder.Default.cs

@@ -185,7 +185,13 @@ public static IEnumerable<Func<HelpContext, bool>> GetLayout()
         public static Func<HelpContext, bool> SynopsisSection() =>
             ctx =>
             {
-                ctx.HelpBuilder.WriteHeading(LocalizationResources.HelpDescriptionTitle(), ctx.Command.Description, ctx.Output);
+                string? description = ctx.Command.Description;
+                if (string.IsNullOrWhiteSpace(description))
+                {
+                    return false;
+                }
+
+                ctx.HelpBuilder.WriteHeading(LocalizationResources.HelpDescriptionTitle(), description, ctx.Output);
                 return true;
             };