Do not use static JsonConvert

Consul.Test/BaseFixture.cs

@@ -4,6 +4,8 @@
 using System.Runtime.ExceptionServices;
 using System.Threading;
 using System.Threading.Tasks;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
 using NuGet.Versioning;
 using Xunit;
 
@@ -85,6 +87,14 @@ public class BaseFixture : IAsyncLifetime
 
         static BaseFixture()
         {
+#if !NETFRAMEWORK // It will not compile for .NET Framework due to ambiguity of Newtonsoft.Json types
+            // We use invalid settings here to make sure that our library doesn't depend on default settings
+            JsonConvert.DefaultSettings = () => new JsonSerializerSettings
+            {
+                TypeNameHandling = TypeNameHandling.Objects,
+            };
+#endif
+
             // Some Consul object (e.g. semaphores) use multiple http connections,
             // but on .NETFramework the default limit is sometimes very low (2) so we need to bump it to higher value.
             // E.g. https://github.com/microsoft/referencesource/blob/5697c29004a34d80acdaf5742d7e699022c64ecd/System.Web/HttpRuntime.cs#L1200

Consul/Client_Request.cs

@@ -57,7 +57,7 @@ public abstract class ConsulRequest
         internal Stream ResponseStream { get; set; }
         internal string Endpoint { get; set; }
 
-        internal readonly JsonSerializer _serializer = new JsonSerializer();
+        private readonly JsonSerializer _serializer = new JsonSerializer();
 
         internal ConsulRequest(ConsulClient client, string url, HttpMethod method)
         {
@@ -120,6 +120,13 @@ protected TOut Deserialize<TOut>(Stream stream)
             }
         }
 
-        protected static byte[] Serialize(object value) => Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(value));
+        protected byte[] Serialize(object value)
+        {
+            using (var sw = new StringWriter())
+            {
+                _serializer.Serialize(sw, value);
+                return Encoding.UTF8.GetBytes(sw.ToString());
+            }
+        }
     }
 }

Consul/Semaphore.cs

@@ -19,6 +19,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.IO;
 using System.Linq;
 using System.Text;
 using System.Threading;
@@ -267,6 +268,7 @@ internal SemaphoreLock()
         private Task _sessionRenewTask;
         private Task _monitorTask;
 
+        private readonly JsonSerializer _serializer = new JsonSerializer();
         internal SemaphoreOptions Opts { get; set; }
 
         public bool IsHeld
@@ -721,14 +723,17 @@ private SemaphoreLock DecodeLock(KVPair pair)
         /// <returns>A K/V pair with the lock data encoded in the Value field</returns>
         private KVPair EncodeLock(SemaphoreLock l, ulong oldIndex)
         {
-            var jsonValue = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(l));
-
-            return new KVPair(string.Join("/", Opts.Prefix, DefaultSemaphoreKey))
+            using (var sw = new StringWriter())
             {
-                Value = jsonValue,
-                Flags = SemaphoreFlagValue,
-                ModifyIndex = oldIndex
-            };
+                _serializer.Serialize(sw, l);
+                var jsonValue = Encoding.UTF8.GetBytes(sw.ToString());
+                return new KVPair(string.Join("/", Opts.Prefix, DefaultSemaphoreKey))
+                {
+                    Value = jsonValue,
+                    Flags = SemaphoreFlagValue,
+                    ModifyIndex = oldIndex
+                };
+            }
         }
 
         /// <summary>