Core - Automatically merge enable-features/disable-features command-line arguments with existing values (#5245)

* Core - Automatically merge `enable-features/disable-features` command-line arguments with existing values

Author: SLT-World

CefSharp.Core.Runtime/Internals/CefSharpApp.h

@@ -209,10 +209,30 @@ namespace CefSharp
 
                         if (kvp->Key == "disable-features" || kvp->Key == "enable-features")
                         {
-                            //Temp workaround so we can set the disable-features/enable-features command line argument
-                            // See https://github.com/cefsharp/CefSharp/issues/2408
-                            commandLine->AppendSwitchWithValue(name, value);
+                            if (CefSharpSettings::MergeFeaturesCommandLineArgs)
+                            {
+                                CefString existingValue = commandLine->GetSwitchValue(name);
+                                if (existingValue.empty())
+                                {
+                                    commandLine->AppendSwitchWithValue(name, value);
+                                }
+                                else
+                                {
+                                    String^ merged = CommandLineArgsMerger::MergeFeatures(StringUtils::ToClr(existingValue), kvp->Value);
+
+                                    commandLine->RemoveSwitch(name);
+                                    commandLine->AppendSwitchWithValue(name, StringUtils::ToNative(merged));
+                                }
+                            }
+                            else
+                            {
+                                //Temp workaround so we can set the disable-features/enable-features command line argument
+                                // See https://github.com/cefsharp/CefSharp/issues/2408
+                                commandLine->RemoveSwitch(name);
+                                commandLine->AppendSwitchWithValue(name, value);
+                            }
                         }
+
                         // Right now the command line args handed to the application (global command line) have higher
                         // precedence than command line args provided by the app
                         else if (!commandLine->HasSwitch(name))

CefSharp.Test/Framework/CommandLineArgsMergerTests.cs

@@ -0,0 +1,63 @@
+// Copyright © 2022 The CefSharp Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+
+using CefSharp.Internals;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace CefSharp.Test.Framework
+{
+    /// <summary>
+    /// CommandLineArgsMergerTests - Test the merging of command line features
+    /// </summary>
+    public class CommandLineArgsMergerTests
+    {
+        private readonly ITestOutputHelper output;
+
+        public CommandLineArgsMergerTests(ITestOutputHelper output)
+        {
+            this.output = output;
+        }
+
+        [Fact]
+        public void ShouldMergeFeatures()
+        {
+            var expected = "A,B,C";
+
+            var actual = CommandLineArgsMerger.MergeFeatures("A,B", "C");
+
+            Assert.Equal(expected, actual);
+        }
+
+        [Fact]
+        public void ShouldAvoidDuplicates()
+        {
+            var expected = "A,B,C";
+
+            var actual = CommandLineArgsMerger.MergeFeatures("A,B", "B,C");
+
+            Assert.Equal(expected, actual);
+        }
+
+        [Fact]
+        public void ShouldTrimWhitespace()
+        {
+            var expected = "A,B,C";
+
+            var actual = CommandLineArgsMerger.MergeFeatures("A, B", " C ");
+
+            Assert.Equal(expected, actual);
+        }
+
+        [Fact]
+        public void ShouldHandleNull()
+        {
+            var expected = "A,B";
+
+            var actual = CommandLineArgsMerger.MergeFeatures("A,B", null);
+
+            Assert.Equal(expected, actual);
+        }
+    }
+}

CefSharp/CefSharpSettings.cs

@@ -21,6 +21,7 @@ static CefSharpSettings()
             WcfTimeout = TimeSpan.FromSeconds(2);
 #endif
             SubprocessExitIfParentProcessClosed = true;
+            MergeFeaturesCommandLineArgs = true;
         }
 
 #if !NETCOREAPP
@@ -82,6 +83,12 @@ static CefSharpSettings()
         /// </summary>
         public static bool FocusedNodeChangedEnabled { get; set; }
 
+        /// <summary>
+        /// Any enable-features/disable-features command line arguments will be automatically merged with existing values if supplied.
+        /// This currently defaults to true.
+        /// </summary>
+        public static bool MergeFeaturesCommandLineArgs { get; set; }
+
         /// <summary>
         /// CefSharp.WinForms and CefSharp.Wpf.HwndHost ONLY!
         /// The default is to create <see cref="CefRuntimeStyle.Alloy"/>

CefSharp/Internals/CommandLineArgsMerger.cs

@@ -0,0 +1,45 @@
+// Copyright © 2015 The CefSharp Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace CefSharp.Internals
+{
+    /// <summary>
+    /// Use this static class to merge command line arguments.
+    /// </summary>
+    public sealed class CommandLineArgsMerger
+    {
+        /// <summary>
+        /// Returns the merged command line features.
+        /// </summary>
+        /// <param name="existing">The existing features.</param>
+        /// <param name="incoming">The features that should be merged.</param>
+        /// <returns> the merged command line features. </returns>
+        public static string MergeFeatures(string existing, string incoming)
+        {
+            var features = new HashSet<string>();
+
+            AddFeatures(features, existing);
+            AddFeatures(features, incoming);
+
+            return string.Join(",", features.OrderBy(i => i));
+        }
+
+        private static void AddFeatures(HashSet<string> features, string value)
+        {
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                return;
+            }
+
+            foreach (var item in value.Split(','))
+            {
+                features.Add(item.Trim());
+            }
+        }
+    }
+}