1 files changed, 19 insertions, 1 deletions
diff --git a/csharp/src/ProtocolBuffers.Test/GeneratedMessageTest.cs b/csharp/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
index e21d904d..26165428 100644
--- a/csharp/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
+++ b/csharp/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
@@ -1,4 +1,5 @@
-using Google.Protobuf.TestProtos;
+using System;
+using Google.Protobuf.TestProtos;
 using NUnit.Framework;
 
 namespace Google.Protobuf
@@ -257,5 +258,22 @@ namespace Google.Protobuf
             original.OneofNestedMessage.Bb = 30;
             Assert.AreNotEqual(original, clone);
         }
+
+        [Test]
+        public void Freeze()
+        {
+            var frozen = new TestAllTypes();
+            frozen.Freeze();
+            Assert.IsTrue(frozen.IsFrozen);
+
+            Assert.Throws<InvalidOperationException>(() => frozen.ClearOneofField());
+            Assert.Throws<InvalidOperationException>(() => frozen.SingleInt32 = 0);
+            Assert.Throws<InvalidOperationException>(() => frozen.SingleNestedMessage = null);
+            Assert.Throws<InvalidOperationException>(() => frozen.SingleNestedEnum = 0);
+            Assert.Throws<InvalidOperationException>(() => frozen.OneofString = null);
+            Assert.Throws<InvalidOperationException>(() => frozen.OneofUint32 = 0U);
+            Assert.Throws<InvalidOperationException>(() => frozen.RepeatedDouble.Add(0.0));
+            Assert.Throws<InvalidOperationException>(() => frozen.RepeatedNestedMessage.Add(new TestAllTypes.Types.NestedMessage()));
+        }
     }
 }