Fix Issue 1340. Bring back default behavior for JsonSerializer.Binder if not set. Added tests.

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

@@ -1341,14 +1341,6 @@ namespace Newtonsoft.Json.Tests.Serialization
             serializer.SerializationBinder = customBinder;
             Assert.AreEqual(customBinder, serializer.SerializationBinder);
 
-            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-#pragma warning disable CS0618 // Type or member is obsolete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-#pragma warning restore CS0618 // Type or member is obsolete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.");
-
             serializer.CheckAdditionalContent = true;
             Assert.AreEqual(true, serializer.CheckAdditionalContent);
 
@@ -1578,14 +1570,6 @@ namespace Newtonsoft.Json.Tests.Serialization
             serializerProxy.SerializationBinder = customBinder;
             Assert.AreEqual(customBinder, serializerProxy.SerializationBinder);
 
-            ExceptionAssert.Throws<InvalidOperationException>(() =>
-            {
-#pragma warning disable CS0618 // Type or member is obsolete
-                var serializationBinder = serializerProxy.Binder;
-#pragma warning restore CS0618 // Type or member is obsolete
-                serializationBinder.ToString();
-            }, "Cannot get SerializationBinder because an ISerializationBinder was previously set.");
-
             serializerProxy.CheckAdditionalContent = true;
             Assert.AreEqual(true, serializerProxy.CheckAdditionalContent);
 

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

@@ -55,6 +55,7 @@ using Newtonsoft.Json.Utilities;
 using System.Net;
 using System.Runtime.Serialization;
 using System.IO;
+using System.Reflection;
 
 namespace Newtonsoft.Json.Tests.Serialization
 {
@@ -883,7 +884,7 @@ namespace Newtonsoft.Json.Tests.Serialization
             }
         }
 #endif
-
+        
         [Test]
         public void NewSerializeUsingCustomBinder()
         {
@@ -1317,6 +1318,7 @@ namespace Newtonsoft.Json.Tests.Serialization
 #endif
 
 #if !(NET20 || NET35)
+
         [Test]
         public void SerializationBinderWithFullName()
         {
@@ -2122,6 +2124,48 @@ namespace Newtonsoft.Json.Tests.Serialization
             StringAssert.AreEqual("Hello!", objWithMessage.Message.Value.Value);
         }
 #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);
+#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);
+        }
+
+
+        public class FancyBinder : ISerializationBinder
+        {
+            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);
+            }
+
+            public Type BindToType(string assemblyName, string typeName)
+            {
+                return null;
+            }
+        }
+#endif
+
     }
 
     public struct Message2

Src/Newtonsoft.Json/JsonSerializer.cs

@@ -117,6 +117,17 @@ namespace Newtonsoft.Json
                     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