Clean up duplicate options in dotnet test

src/Cli/dotnet/Commands/Test/TestingPlatformCommand.Help.cs

@@ -29,7 +29,7 @@ public IEnumerable<Action<HelpContext>> CustomHelpLayout()
                 return;
             }
 
-            Dictionary<bool, List<CommandLineOption>> allOptions = GetAllOptions();
+            Dictionary<bool, List<CommandLineOption>> allOptions = GetAllOptions(context.Command.Options);
             allOptions.TryGetValue(true, out List<CommandLineOption> builtInOptions);
             allOptions.TryGetValue(false, out List<CommandLineOption> nonBuiltInOptions);
 
@@ -128,29 +128,36 @@ private void OnHelpRequested(object sender, HelpEventArgs args)
            (isBuiltIn, value) => [.. value, (moduleName, nonBuiltInOptions.ToArray())]);
     }
 
-    private Dictionary<bool, List<CommandLineOption>> GetAllOptions()
+    private Dictionary<bool, List<CommandLineOption>> GetAllOptions(IList<Option> commandOptions)
     {
-        Dictionary<bool, List<CommandLineOption>> builtInToOptions = [];
+        Dictionary<bool, List<CommandLineOption>> filteredOptions = [];
+
+        // Create a set of option names from the command's options for efficient lookup
+        var commandOptionNames = commandOptions.Select(o => o.Name.TrimStart('-')).ToHashSet(StringComparer.OrdinalIgnoreCase);
 
         foreach (KeyValuePair<string, CommandLineOption> option in _commandLineOptionNameToModuleNames)
         {
-            if (!builtInToOptions.TryGetValue(option.Value.IsBuiltIn.Value, out List<CommandLineOption> value))
-            {
-                builtInToOptions.Add(option.Value.IsBuiltIn.Value, [option.Value]);
-            }
-            else
+            // Only include options that are NOT already present in the command's options
+            if (!commandOptionNames.Contains(option.Value.Name))
             {
-                value.Add(option.Value);
+                if (!filteredOptions.TryGetValue(option.Value.IsBuiltIn.Value, out List<CommandLineOption> value))
+                {
+                    filteredOptions.Add(option.Value.IsBuiltIn.Value, [option.Value]);
+                }
+                else
+                {
+                    value.Add(option.Value);
+                }
             }
         }
 
         // Sort options alphabetically by name
-        foreach (var optionsList in builtInToOptions.Values)
+        foreach (var optionsList in filteredOptions.Values)
         {
             optionsList.Sort((x, y) => string.Compare(x.Name, y.Name, StringComparison.OrdinalIgnoreCase));
         }
 
-        return builtInToOptions;
+        return filteredOptions;
     }
 
     private static Dictionary<bool, List<(string[], string[])>> GetModulesToMissingOptions(

test/dotnet.Tests/CommandTests/Test/GivenDotnetTestBuildsAndRunsHelp.cs

@@ -62,5 +62,55 @@ public void RunHelpOnMultipleTestProjects_ShouldReturnExitCodeSuccess(string con
 
             result.ExitCode.Should().Be(ExitCodes.Success);
         }
+
+        [InlineData(TestingConstants.Debug)]
+        [InlineData(TestingConstants.Release)]
+        [Theory]
+        public void RunHelpCommand_ShouldNotShowDuplicateOptions(string configuration)
+        {
+            TestAsset testInstance = _testAssetsManager.CopyTestAsset("TestProjectSolutionWithTestsAndArtifacts", Guid.NewGuid().ToString()).WithSource();
+
+            CommandResult result = new DotnetTestCommand(Log, disableNewOutput: false)
+                                    .WithWorkingDirectory(testInstance.Path)
+                                    .Execute(TestingPlatformOptions.HelpOption.Name, TestingPlatformOptions.ConfigurationOption.Name, configuration);
+
+            // Parse the help output to extract option names
+            var helpOutput = result.StdOut;
+
+            // Check for specific options we care about
+            string outputOptionName = TestingPlatformOptions.OutputOption.Name; // --output
+            string noAnsiOptionName = TestingPlatformOptions.NoAnsiOption.Name; // --no-ansi
+
+            // Count occurrences of each option in the help output
+            int outputOptionCount = CountOptionOccurrences(helpOutput!, outputOptionName);
+            int noAnsiOptionCount = CountOptionOccurrences(helpOutput!, noAnsiOptionName);
+
+            // Assert that each option appears only once
+            outputOptionCount.Should().Be(1, $"Option '{outputOptionName}' should not appear more than once in help output");
+            noAnsiOptionCount.Should().Be(1, $"Option '{noAnsiOptionName}' should not appear more than once in help output");
+
+            result.ExitCode.Should().Be(ExitCodes.Success);
+        }
+
+        private static int CountOptionOccurrences(string helpOutput, string optionName)
+        {
+            // Split by lines and look for lines that start with the option (accounting for indentation)
+            var lines = helpOutput.Split('\n', StringSplitOptions.RemoveEmptyEntries);
+            int count = 0;
+
+            foreach (var line in lines)
+            {
+                var trimmedLine = line.Trim();
+                // Look for lines that start with the option name (e.g., "--output" or "--no-ansi")
+                if (trimmedLine.StartsWith(optionName, StringComparison.OrdinalIgnoreCase))
+                {
+                    count++;
+                }
+            }
+
+            return count;
+        }
+
+
     }
 }