[dotnet] Serialize command parameters directly to UTF-8

dotnet/src/webdriver/Command.cs

@@ -101,13 +101,29 @@ public string ParametersAsJsonString
             }
         }
 
+        /// <summary>
+        /// Serializes the parameters of the comand to JSON as UTF-8 bytes.
+        /// </summary>
+        /// <returns></returns>
+        public byte[] GetParametersAsUtf8Bytes()
+        {
+            if (this.Parameters != null && this.Parameters.Count > 0)
+            {
+                return JsonSerializer.SerializeToUtf8Bytes(this.Parameters, s_jsonSerializerOptions);
+            }
+            else
+            {
+                return "{}"u8.ToArray();
+            }
+        }
+
         /// <summary>
         /// Returns a string of the Command object
         /// </summary>
         /// <returns>A string representation of the Command Object</returns>
         public override string ToString()
         {
-            return string.Concat("[", this.SessionId, "]: ", this.Name, " ", this.ParametersAsJsonString);
+            return $"[{this.SessionId}]: {this.Name} {this.ParametersAsJsonString}";
         }
 
         /// <summary>

dotnet/src/webdriver/Remote/HttpCommandExecutor.cs

@@ -280,7 +280,7 @@ private async Task<HttpResponseInfo> MakeHttpRequest(HttpRequestInfo requestInfo
                     acceptHeader.CharSet = Utf8CharsetType;
                     requestMessage.Headers.Accept.Add(acceptHeader);
 
-                    byte[] bytes = Encoding.UTF8.GetBytes(requestInfo.RequestBody);
+                    byte[] bytes = requestInfo.RequestBody;
                     requestMessage.Content = new ByteArrayContent(bytes, 0, bytes.Length);
 
                     MediaTypeHeaderValue contentTypeHeader = new MediaTypeHeaderValue(JsonMimeType);
@@ -370,12 +370,12 @@ public HttpRequestInfo(Uri serverUri, Command commandToExecute, HttpCommandInfo
 
                 this.FullUri = commandInfo.CreateCommandUri(serverUri, commandToExecute);
                 this.HttpMethod = commandInfo.Method;
-                this.RequestBody = commandToExecute.ParametersAsJsonString;
+                this.RequestBody = commandToExecute.GetParametersAsUtf8Bytes();
             }
 
             public Uri FullUri { get; set; }
             public string HttpMethod { get; set; }
-            public string RequestBody { get; set; }
+            public byte[] RequestBody { get; set; }
         }
 
         private class HttpResponseInfo

dotnet/src/webdriver/Remote/SendingRemoteHttpRequestEventArgs.cs

@@ -19,6 +19,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Text;
 
 #nullable enable
 
@@ -29,6 +30,8 @@ namespace OpenQA.Selenium.Remote
     /// </summary>
     public class SendingRemoteHttpRequestEventArgs : EventArgs
     {
+        private string? _requestBody;
+        private readonly byte[]? _utf8RequestBody;
         private readonly Dictionary<string, string> headers = new Dictionary<string, string>();
 
         /// <summary>
@@ -42,7 +45,21 @@ public SendingRemoteHttpRequestEventArgs(string method, string fullUrl, string?
         {
             this.Method = method ?? throw new ArgumentNullException(nameof(method));
             this.FullUrl = fullUrl ?? throw new ArgumentNullException(nameof(fullUrl));
-            this.RequestBody = requestBody;
+            _utf8RequestBody = requestBody is null ? null : Encoding.UTF8.GetBytes(requestBody);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SendingRemoteHttpRequestEventArgs"/> class.
+        /// </summary>
+        /// <param name="method">The HTTP method of the request being sent.</param>
+        /// <param name="fullUrl">The full URL of the request being sent.</param>
+        /// <param name="requestBody">The body of the request.</param>
+        /// <exception cref="ArgumentNullException">If <paramref name="method"/>, <paramref name="fullUrl"/> are null.</exception>
+        public SendingRemoteHttpRequestEventArgs(string method, string fullUrl, byte[]? requestBody)
+        {
+            this.Method = method ?? throw new ArgumentNullException(nameof(method));
+            this.FullUrl = fullUrl ?? throw new ArgumentNullException(nameof(fullUrl));
+            _utf8RequestBody = requestBody;
         }
 
         /// <summary>
@@ -58,7 +75,18 @@ public SendingRemoteHttpRequestEventArgs(string method, string fullUrl, string?
         /// <summary>
         /// Gets the body of the HTTP request as a string.
         /// </summary>
-        public string? RequestBody { get; }
+        public string? RequestBody
+        {
+            get
+            {
+                if (_requestBody is not null)
+                {
+                    return _requestBody;
+                }
+
+                return _requestBody = _utf8RequestBody is null ? null : Encoding.UTF8.GetString(_utf8RequestBody);
+            }
+        }
 
         /// <summary>
         /// Gets a read-only dictionary of the headers of the HTTP request.

dotnet/test/common/CommandTests.cs

@@ -25,6 +25,22 @@ namespace OpenQA.Selenium
     [TestFixture]
     public class CommandTests
     {
+        [Test]
+        public void CommandSerializesNullParameters()
+        {
+            var command = new Command(new SessionId("session"), "test command", parameters: null);
+
+            Assert.That(command.GetParametersAsUtf8Bytes(), Is.EqualTo("{}"u8.ToArray()));
+        }
+
+        [Test]
+        public void CommandSerializesEmptyParameters()
+        {
+            var command = new Command(new SessionId("session"), "test command", parameters: new Dictionary<string, object>());
+
+            Assert.That(command.GetParametersAsUtf8Bytes(), Is.EqualTo("{}"u8.ToArray()));
+        }
+
         [Test]
         public void CommandSerializesAnonymousType()
         {
@@ -35,7 +51,7 @@ public void CommandSerializesAnonymousType()
 
             var command = new Command(new SessionId("session"), "test command", parameters);
 
-            Assert.That(command.ParametersAsJsonString, Is.EqualTo("""{"arg":{"param1":true,"param2":false}}"""));
+            Assert.That(command.GetParametersAsUtf8Bytes(), Is.EqualTo("""{"arg":{"param1":true,"param2":false}}"""u8.ToArray()));
         }
     }
 }