-Refactor

Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs

@@ -1341,6 +1341,11 @@ namespace Newtonsoft.Json.Tests.Serialization
             serializer.SerializationBinder = customBinder;
             Assert.AreEqual(customBinder, serializer.SerializationBinder);
 
+#pragma warning disable CS0618 // Type or member is obsolete
+            // can still fetch because DefaultSerializationBinder inherits from SerializationBinder
+            Assert.AreEqual(customBinder, serializer.Binder);
+#pragma warning restore CS0618 // Type or member is obsolete
+
             serializer.CheckAdditionalContent = true;
             Assert.AreEqual(true, serializer.CheckAdditionalContent);
 
@@ -1570,6 +1575,12 @@ namespace Newtonsoft.Json.Tests.Serialization
             serializerProxy.SerializationBinder = customBinder;
             Assert.AreEqual(customBinder, serializerProxy.SerializationBinder);
 
+#pragma warning disable CS0618 // Type or member is obsolete
+            // can still fetch because DefaultSerializationBinder inherits from SerializationBinder
+            Assert.AreEqual(customBinder, serializerProxy.Binder);
+#pragma warning restore CS0618 // Type or member is obsolete
+
+
             serializerProxy.CheckAdditionalContent = true;
             Assert.AreEqual(true, serializerProxy.CheckAdditionalContent);
 

Src/Newtonsoft.Json.Tests/Serialization/TypeNameHandlingTests.cs

@@ -884,7 +884,7 @@ namespace Newtonsoft.Json.Tests.Serialization
             }
         }
 #endif
-        
+
         [Test]
         public void NewSerializeUsingCustomBinder()
         {
@@ -1318,7 +1318,6 @@ namespace Newtonsoft.Json.Tests.Serialization
 #endif
 
 #if !(NET20 || NET35)
-
         [Test]
         public void SerializationBinderWithFullName()
         {
@@ -2125,38 +2124,41 @@ namespace Newtonsoft.Json.Tests.Serialization
         }
 #endif
 
-
 #if !(NET20 || NET35)
-
         [Test]
         public void SerializerWithDefaultBinder()
         {
             var serializer = JsonSerializer.Create();
 #pragma warning disable CS0618
             Assert.NotNull(serializer.Binder);
-            StringAssert.Equals(typeof(DefaultSerializationBinder).FullName, serializer.Binder.GetType().FullName);
+            Assert.IsInstanceOf(typeof(DefaultSerializationBinder), serializer.Binder);
 #pragma warning restore CS0618 // Type or member is obsolete
-            StringAssert.Equals(typeof(DefaultSerializationBinder).FullName, serializer.SerializationBinder.GetType().FullName);
-        }
-        
-        [Test]
-        public void ObsoleteBinderThrowsIfISerializationBinderSet()
-        {   
-            var serializer = JsonSerializer.Create(new JsonSerializerSettings() { SerializationBinder = new FancyBinder() });
-#pragma warning disable CS0618
-            Assert.Throws<InvalidOperationException>(() => { var foo = serializer.Binder; });
-#pragma warning restore CS0618 // Type or member is obsolete
-            StringAssert.Equals(typeof(FancyBinder).Name, serializer.SerializationBinder.GetType().Name);
+            Assert.IsInstanceOf(typeof(DefaultSerializationBinder), serializer.SerializationBinder);
         }
 
+        [Test]
+        public void ObsoleteBinderThrowsIfISerializationBinderSet()
+        {
+            var serializer = JsonSerializer.Create(new JsonSerializerSettings() { SerializationBinder = new FancyBinder() });
+            ExceptionAssert.Throws<InvalidOperationException>(() =>
+            {
+#pragma warning disable CS0618 // Type or member is obsolete
+                var serializationBinder = serializer.Binder;
+#pragma warning restore CS0618 // Type or member is obsolete
+                serializationBinder.ToString();
+            }, "Cannot get SerializationBinder because an ISerializationBinder was previously set.");
+
+            Assert.IsInstanceOf(typeof(FancyBinder), serializer.SerializationBinder);
+        }
 
         public class FancyBinder : ISerializationBinder
         {
-            string annotate = new string(':', 3);
+            private static readonly string Annotate = new string(':', 3);
+
             public void BindToName(Type serializedType, out string assemblyName, out string typeName)
             {
                 assemblyName = string.Format("FancyAssemblyName=>{0}", Assembly.GetAssembly(serializedType)?.GetName().Name);
-                typeName = string.Format("{0}{1}{0}", annotate, serializedType.Name);
+                typeName = string.Format("{0}{1}{0}", Annotate, serializedType.Name);
             }
 
             public Type BindToType(string assemblyName, string typeName)
@@ -2165,7 +2167,6 @@ namespace Newtonsoft.Json.Tests.Serialization
             }
         }
 #endif
-
     }
 
     public struct Message2

Src/Newtonsoft.Json/JsonSerializer.cs

@@ -111,23 +111,18 @@ namespace Newtonsoft.Json
                     return null;
                 }
 
+                SerializationBinder legacySerializationBinder = _serializationBinder as SerializationBinder;
+                if (legacySerializationBinder != null)
+                {
+                    return legacySerializationBinder;
+                }
+
                 SerializationBinderAdapter adapter = _serializationBinder as SerializationBinderAdapter;
                 if (adapter != null)
                 {
                     return adapter.SerializationBinder;
                 }
 
-                //Check if Default Binder was set
-                if (_serializationBinder.GetType().IsAssignableFrom(typeof(DefaultSerializationBinder)))
-                {
-                    adapter = new SerializationBinderAdapter(_serializationBinder as DefaultSerializationBinder);
-                }
-
-                if (adapter != null)
-                {
-                    return adapter.SerializationBinder;
-                }
-
                 throw new InvalidOperationException("Cannot get SerializationBinder because an ISerializationBinder was previously set.");
             }
             set