-Changed ISerializable serialization to require SerializableAttribute

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

@@ -125,6 +125,15 @@ namespace Newtonsoft.Json.Tests.Serialization
             Assert.AreEqual(JsonContractType.Serializable, contract.ContractType);
         }
 
+        [Test]
+        public void ResolveSerializableWithoutAttributeContract()
+        {
+            DefaultContractResolver contractResolver = new DefaultContractResolver();
+            JsonContract contract = contractResolver.ResolveContract(typeof(ISerializableWithoutAttributeTestObject));
+
+            Assert.AreEqual(JsonContractType.Object, contract.ContractType);
+        }
+
         [Test]
         public void ResolveObjectContractWithFieldsSerialization()
         {

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

@@ -152,6 +152,7 @@ namespace Newtonsoft.Json.Tests.Serialization
         }
 
 #if !(PORTABLE || DNXCORE50 || PORTABLE40) || NETSTANDARD1_3 || NETSTANDARD2_0
+        [Serializable]
         public class MainClass : ISerializable
         {
             public ChildClass Child { get; set; }
@@ -162,6 +163,7 @@ namespace Newtonsoft.Json.Tests.Serialization
             }
         }
 
+        [Serializable]
         public class ChildClass : ISerializable
         {
             public string Name { get; set; }

Src/Newtonsoft.Json.Tests/TestObjects/ISerializableTestObject.cs

@@ -29,6 +29,7 @@ using Newtonsoft.Json.Tests.TestObjects.Organization;
 
 namespace Newtonsoft.Json.Tests.TestObjects
 {
+    [Serializable]
     public class ISerializableTestObject : ISerializable
     {
         internal string _stringValue;

Src/Newtonsoft.Json.Tests/TestObjects/ISerializableWithoutAttributeTestObject.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Runtime.Serialization;
+
+namespace Newtonsoft.Json.Tests.TestObjects
+{
+    public class ISerializableWithoutAttributeTestObject : ISerializable
+    {
+        public void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

Src/Newtonsoft.Json.Tests/TestObjects/PreserveReferencesCallbackTestObject.cs

@@ -23,11 +23,13 @@
 // OTHER DEALINGS IN THE SOFTWARE.
 #endregion
 
+using System;
 using System.Runtime.Serialization;
 
 namespace Newtonsoft.Json.Tests.TestObjects
 {
 #if !(PORTABLE || PORTABLE40 || DNXCORE50) || NETSTANDARD1_3 || NETSTANDARD2_0
+    [Serializable]
     public class PreserveReferencesCallbackTestObject : ISerializable
     {
         internal string _stringValue;

Src/Newtonsoft.Json.Tests/TestObjects/Ratio.cs

@@ -30,6 +30,7 @@ using System.Runtime.Serialization;
 namespace Newtonsoft.Json.Tests.TestObjects
 {
 #if !(DNXCORE50) || NETSTANDARD1_3 || NETSTANDARD2_0
+    [Serializable]
     public struct Ratio : IConvertible, IFormattable, ISerializable
     {
         private readonly int _numerator;

Src/Newtonsoft.Json/Serialization/DefaultContractResolver.cs

@@ -1171,7 +1171,7 @@ namespace Newtonsoft.Json.Serialization
             }
 
 #if HAVE_BINARY_SERIALIZATION
-            if (!IgnoreSerializableInterface && typeof(ISerializable).IsAssignableFrom(t))
+            if (!IgnoreSerializableInterface && typeof(ISerializable).IsAssignableFrom(t) && JsonTypeReflector.IsSerializable(t))
             {
                 return CreateISerializableContract(objectType);
             }

Src/Newtonsoft.Json/Serialization/JsonTypeReflector.cs

@@ -383,7 +383,8 @@ namespace Newtonsoft.Json.Serialization
         public static bool IsNonSerializable(object provider)
         {
 #if HAVE_FULL_REFLECTION
-            return (GetCachedAttribute<NonSerializedAttribute>(provider) != null);
+            // no inheritance
+            return (ReflectionUtils.GetAttribute<NonSerializedAttribute>(provider, false) != null);
 #else
             FieldInfo fieldInfo = provider as FieldInfo;
             if (fieldInfo != null && (fieldInfo.Attributes & FieldAttributes.NotSerialized) == FieldAttributes.NotSerialized)
@@ -400,7 +401,8 @@ namespace Newtonsoft.Json.Serialization
         public static bool IsSerializable(object provider)
         {
 #if HAVE_FULL_REFLECTION
-            return (GetCachedAttribute<SerializableAttribute>(provider) != null);
+            // no inheritance
+            return (ReflectionUtils.GetAttribute<SerializableAttribute>(provider, false) != null);
 #else
             Type type = provider as Type;
             if (type != null && (type.GetTypeInfo().Attributes & TypeAttributes.Serializable) == TypeAttributes.Serializable)