Update JsonSerializerOptionsTests.cs

Add basic test

Author: networkfusion

nanoFramework.Json.Test/JsonSerializerOptionsTests.cs

@@ -119,6 +119,19 @@ public void Can_serialize_and_deserialize_arrays_of_class_objects()
             OutputHelper.WriteLine("");
         }
 
+        [TestMethod]
+        public void Can_deserialize_string_starting_with_unicode_escape()
+        {
+            // escaped JSON: "Product":"\u00315 litres" -> Product = "5 liters"
+            var json = "{\"Product\":\"\\u00315 litres\",\"Count\":10}";
+
+            var item = JsonConvert.DeserializeObject(json, typeof(Item)) as Item;
+
+            Assert.NotNull(item);
+            Assert.Equal("5 liters", item.Product);
+            Assert.Equal(10, item.Count);
+        }
+
         [TestMethod]
         public void Can_serialize_and_deserialize_arrays_of_class_objects_when_array_items_may_be_null()
         {