Fix deserializing empty string to empty byte array (#1787)

Src/Newtonsoft.Json.Tests/Issues/Issue1752.cs

@@ -0,0 +1,84 @@
+#region License
+// Copyright (c) 2007 James Newton-King
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Reflection.Emit;
+using System.Runtime.Serialization;
+#if !(NET20 || NET35 || NET40 || PORTABLE40)
+using System.Threading.Tasks;
+#endif
+using Newtonsoft.Json.Converters;
+using Newtonsoft.Json.Linq;
+using Newtonsoft.Json.Serialization;
+using Newtonsoft.Json.Utilities;
+#if DNXCORE50
+using Xunit;
+using Test = Xunit.FactAttribute;
+using Assert = Newtonsoft.Json.Tests.XUnitAssert;
+#else
+using NUnit.Framework;
+#endif
+
+namespace Newtonsoft.Json.Tests.Issues
+{
+    [TestFixture]
+    public class Issue1752 : TestFixtureBase
+    {
+        [Test]
+        public void Test_EmptyString()
+        {
+            JsonSerializerSettings settings = new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.Auto };
+
+            string s1 = JsonConvert.SerializeObject(new TestObject() { Obj = new byte[] { } }, settings);
+
+            TestObject t1 = JsonConvert.DeserializeObject<TestObject>(s1, settings);
+            Assert.IsNotNull(t1.Obj);
+
+            byte[] data = (byte[])t1.Obj;
+            Assert.AreEqual(0, data.Length);
+        }
+
+        [Test]
+        public void Test_Null()
+        {
+            TestObject1 t1 = JsonConvert.DeserializeObject<TestObject1>("{'Obj':null}");
+            Assert.IsNull(t1.Obj);
+        }
+
+        class TestObject
+        {
+            public object Obj { get; set; }
+        }
+
+        class TestObject1
+        {
+            public byte[] Obj { get; set; }
+        }
+    }
+}

Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs

@@ -303,18 +303,18 @@ namespace Newtonsoft.Json.Serialization
                     case JsonToken.String:
                         string s = (string)reader.Value;
 
-                        // convert empty string to null automatically for nullable types
-                        if (CoerceEmptyStringToNull(objectType, contract, s))
-                        {
-                            return null;
-                        }
-
                         // string that needs to be returned as a byte array should be base 64 decoded
                         if (objectType == typeof(byte[]))
                         {
                             return Convert.FromBase64String(s);
                         }
 
+                        // convert empty string to null automatically for nullable types
+                        if (CoerceEmptyStringToNull(objectType, contract, s))
+                        {
+                            return null;
+                        }
+
                         return EnsureType(reader, s, CultureInfo.InvariantCulture, contract, objectType);
                     case JsonToken.StartConstructor:
                         string constructorName = reader.Value.ToString();