Check offset separately for DateTimeOffset types

Author: mattjohnsonpint

src/System.Runtime.Serialization.Xml/tests/DataContractSerializer.cs

@@ -43,7 +43,10 @@ public static void DCS_DateTimeOffsetAsRoot()
         };
         for (int i = 0; i < objs.Length; ++i)
         {
-            Assert.StrictEqual(SerializeAndDeserialize<DateTimeOffset>(objs[i], serializedStrings[i]), objs[i]);
+            var actual = objs[i];
+            var expected = SerializeAndDeserialize<DateTimeOffset>(actual, serializedStrings[i]);
+            Assert.StrictEqual(expected, actual);
+            Assert.StrictEqual(expected.Offset, actual.Offset);
         }
     }
 
@@ -1360,16 +1363,19 @@ public static void DCS_TypeWithDatetimeOffsetTypeProperty()
         var value = new TypeWithDateTimeOffsetTypeProperty() { ModifiedTime = new DateTimeOffset(new DateTime(2013, 1, 2, 3, 4, 5, 6, DateTimeKind.Utc)) };
         var actual = SerializeAndDeserialize(value, "<TypeWithDateTimeOffsetTypeProperty xmlns=\"http://schemas.datacontract.org/2004/07/SerializationTypes\" xmlns:i=\"http://www.w3.org/2001/XMLSchema-instance\"><ModifiedTime xmlns:a=\"http://schemas.datacontract.org/2004/07/System\"><a:DateTime>2013-01-02T03:04:05.006Z</a:DateTime><a:OffsetMinutes>0</a:OffsetMinutes></ModifiedTime></TypeWithDateTimeOffsetTypeProperty>");
         Assert.StrictEqual(value.ModifiedTime, actual.ModifiedTime);
+        Assert.StrictEqual(value.ModifiedTime.Offset, actual.ModifiedTime.Offset);
 
         var offsetMinutes = TimeZoneInfo.Local.BaseUtcOffset.TotalMinutes;
         // Adding offsetMinutes to ModifiedTime property so the DateTime component in serialized strings are time-zone independent
         value = new TypeWithDateTimeOffsetTypeProperty() { ModifiedTime = new DateTimeOffset(new DateTime(2013, 1, 2, 3, 4, 5, 6).AddMinutes(offsetMinutes)) };
         actual = SerializeAndDeserialize(value, string.Format("<TypeWithDateTimeOffsetTypeProperty xmlns=\"http://schemas.datacontract.org/2004/07/SerializationTypes\" xmlns:i=\"http://www.w3.org/2001/XMLSchema-instance\"><ModifiedTime xmlns:a=\"http://schemas.datacontract.org/2004/07/System\"><a:DateTime>2013-01-02T03:04:05.006Z</a:DateTime><a:OffsetMinutes>{0}</a:OffsetMinutes></ModifiedTime></TypeWithDateTimeOffsetTypeProperty>", offsetMinutes));
         Assert.StrictEqual(value.ModifiedTime, actual.ModifiedTime);
+        Assert.StrictEqual(value.ModifiedTime.Offset, actual.ModifiedTime.Offset);
 
         value = new TypeWithDateTimeOffsetTypeProperty() { ModifiedTime = new DateTimeOffset(new DateTime(2013, 1, 2, 3, 4, 5, 6, DateTimeKind.Local).AddMinutes(offsetMinutes)) };
         actual = SerializeAndDeserialize(value, string.Format("<TypeWithDateTimeOffsetTypeProperty xmlns=\"http://schemas.datacontract.org/2004/07/SerializationTypes\" xmlns:i=\"http://www.w3.org/2001/XMLSchema-instance\"><ModifiedTime xmlns:a=\"http://schemas.datacontract.org/2004/07/System\"><a:DateTime>2013-01-02T03:04:05.006Z</a:DateTime><a:OffsetMinutes>{0}</a:OffsetMinutes></ModifiedTime></TypeWithDateTimeOffsetTypeProperty>", offsetMinutes));
         Assert.StrictEqual(value.ModifiedTime, actual.ModifiedTime);
+        Assert.StrictEqual(value.ModifiedTime.Offset, actual.ModifiedTime.Offset);
     }
 
     [Fact]