From 7d46b3008a5a4002fd12a13b2f94a83a02975e76 Mon Sep 17 00:00:00 2001
From: gnovack <50467879+gnovack@users.noreply.github.com>
Date: Thu, 16 May 2019 19:35:08 -0400
Subject: [PATCH] Fixed deserialization of null arrays for issue
 dotnet/corefx#37606 (dotnet/corefx#37616)

* Fixed deserialization of null root arrays.

* Used reader.CurrentDepth to catch root level nulls.


Commit migrated from https://github.com/dotnet/corefx/commit/026fa6a6889ab1c9c8f14f55d414d2940fc59805
---
 .../JsonSerializer.Read.HandleNull.cs              |  4 +--
 .../tests/Serialization/Null.ReadTests.cs          | 38 +++++++++++++++++++++-
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Read.HandleNull.cs b/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Read.HandleNull.cs
index 80abfc4..7f7ecb1 100644
--- a/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Read.HandleNull.cs
+++ b/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Read.HandleNull.cs
@@ -16,8 +16,8 @@ namespace System.Text.Json.Serialization
                 return false;
             }
 
-            // If we don't have a valid property, that means we read "null" for a root object so just return.
-            if (state.Current.JsonPropertyInfo == null)
+            // If null is read at the top level and the type is nullable, then the root is "null" so just return.
+            if (reader.CurrentDepth == 0 && (state.Current.JsonPropertyInfo == null || state.Current.JsonPropertyInfo.CanBeNull))
             {
                 Debug.Assert(state.IsLastFrame);
                 Debug.Assert(state.Current.ReturnValue == null);
diff --git a/src/libraries/System.Text.Json/tests/Serialization/Null.ReadTests.cs b/src/libraries/System.Text.Json/tests/Serialization/Null.ReadTests.cs
index ce12143..34f6cae 100644
--- a/src/libraries/System.Text.Json/tests/Serialization/Null.ReadTests.cs
+++ b/src/libraries/System.Text.Json/tests/Serialization/Null.ReadTests.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using Xunit;
 
 namespace System.Text.Json.Serialization.Tests
@@ -17,7 +18,7 @@ namespace System.Text.Json.Serialization.Tests
 
         [Fact]
         public static void RootObjectIsNull()
-        {
+        { 
             {
                 TestClassWithNull obj = JsonSerializer.Parse<TestClassWithNull>("null");
                 Assert.Null(obj);
@@ -27,6 +28,41 @@ namespace System.Text.Json.Serialization.Tests
                 object obj = JsonSerializer.Parse<object>("null");
                 Assert.Null(obj);
             }
+
+            {
+                string obj = JsonSerializer.Parse<string>("null");
+                Assert.Null(obj);
+            }
+
+            {
+                IEnumerable<int> obj = JsonSerializer.Parse<IEnumerable<int>>("null");
+                Assert.Null(obj);
+            }
+
+            {
+                Dictionary<string, object> obj = JsonSerializer.Parse<Dictionary<string, object>>("null");
+                Assert.Null(obj);
+            }
+
+        }
+
+        [Fact]
+        public static void RootArrayIsNull()
+        {
+            {
+                int[] obj = JsonSerializer.Parse<int[]>("null");
+                Assert.Null(obj);
+            }
+
+            {
+                object[] obj = JsonSerializer.Parse<object[]>("null");
+                Assert.Null(obj);
+            }
+
+            {
+                TestClassWithNull[] obj = JsonSerializer.Parse<TestClassWithNull[]>("null");
+                Assert.Null(obj);
+            }
         }
 
         [Fact]
-- 
2.7.4