Fix deserializing read-only empty collection

Author: mythz

src/ServiceStack.Text/Common/DeserializeListWithElements.cs

@@ -128,7 +128,8 @@ public static ICollection<T> ParseGenericList(string value, Type createListType,
                 ? new List<T>()
                 : (ICollection<T>)createListType.CreateInstance();
 
-            if (value == string.Empty) return to;
+            if (value == string.Empty)
+                return isReadOnly ? (ICollection<T>)Activator.CreateInstance(createListType, to) : to;
 
             var tryToParseItemsAsPrimitiveTypes =
                 JsConfig.TryToParsePrimitiveTypeValues && typeof(T) == typeof(object);

tests/ServiceStack.Text.Tests/JsonTests/JsonEnnumerableTests.cs

@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using NUnit.Framework;
+using ServiceStack;
+using ServiceStack.Text;
+using System.Collections.ObjectModel;
+
+namespace ServiceStack.Text.Tests.JsonTests
+{
+    public class JsonEnnumerableTests
+    {
+        public class ModelWithReadOnlyCollection
+        {
+            public ReadOnlyCollection<string> Results { get; set; }
+        }
+
+        [Test]
+        public void Does_deserialize_Empty_ReadOnlyCollection()
+        {
+            var dto = "{\"Results\":[]}".FromJson<ModelWithReadOnlyCollection>();
+            Assert.That(dto.Results.Count, Is.EqualTo(0));
+        }
+
+        public class ModelWithList
+        {
+            public List<string> Results { get; set; }
+        }
+
+        [Test]
+        public void Does_deserialize_Empty_List()
+        {
+            var dto = "{\"Results\":[]}".FromJson<ModelWithList>();
+            Assert.That(dto.Results.Count, Is.EqualTo(0));
+        }
+    }
+}

tests/ServiceStack.Text.Tests/ServiceStack.Text.Tests.csproj

@@ -196,6 +196,7 @@
     <Compile Include="JsonTests\InheritAbstractTests.cs" />
     <Compile Include="JsonTests\InheritanceTests.cs" />
     <Compile Include="JsonTests\JsonDecimalTests.cs" />
+    <Compile Include="JsonTests\JsonEnnumerableTests.cs" />
     <Compile Include="JsonTests\JsonEnumTests.cs" />
     <Compile Include="JsonTests\InvalidJsonTests.cs" />
     <Compile Include="JsonTests\OnDeserializationErrorTests.cs" />