Index: R/serialize.R
===================================================================
--- R/serialize.R	(revision 453)
+++ R/serialize.R	(working copy)
@@ -7,7 +7,7 @@
 setGeneric( "serialize" )
 setMethod( "serialize", c( object = "Message" ) , 
 	function( object, connection, ascii = FALSE, refhook = NULL){
-		
+                stopifnot(object$isInitialized())
 		iscon <- inherits(connection, "connection")
 		isnull <- is.null( connection )
 		
@@ -42,4 +42,3 @@
 		}
 	}
 )
-
Index: inst/unitTests/runit.serialize.R
===================================================================
--- inst/unitTests/runit.serialize.R	(revision 0)
+++ inst/unitTests/runit.serialize.R	(revision 0)
@@ -0,0 +1,41 @@
+# Copyright 2012 Google Inc. All Rights Reserved.
+# Author: Murray Stokely
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+
+# this is executed before each test function
+.setUp <- function(){
+	if( !exists("tutorial.Person", "RProtoBuf:DescriptorPool") ) {
+		unitest.proto.file <- system.file("proto", "addressbook.proto",
+                                                  package = "RProtoBuf" )
+		readProtoFiles(file = unitest.proto.file)
+	}
+}
+
+test.serialize <- function() {
+        person <- new(tutorial.Person)
+
+        checkTrue(!person$isInitialized())
+        checkException(serialize(person, NULL),
+                "Uninitialized object should fail to serialize.")
+        person$id <- 1
+        checkException(serialize(person, NULL),
+                "Uninitialized object should fail to serialize.")
+        person$name <- "Murray"
+
+        checkTrue(person$isInitialized())
+        checkTrue(length(serialize(person, NULL)) > 1)
+}