diff --git a/py_gen/tests/of13.py b/py_gen/tests/of13.py
index 5689a94..55cd20f 100644
--- a/py_gen/tests/of13.py
+++ b/py_gen/tests/of13.py
@@ -26,6 +26,7 @@
 # EPL for the specific language governing permissions and limitations
 # under the EPL.
 import unittest
+import difflib
 
 try:
     import loxi.of13 as ofp
@@ -33,6 +34,35 @@
 except ImportError:
     exit("loxi package not found. Try setting PYTHONPATH.")
 
+# Human-friendly format for binary strings. 8 bytes per line.
+def format_binary(buf):
+    byts = map(ord, buf)
+    lines = [[]]
+    for byt in byts:
+        if len(lines[-1]) == 8:
+            lines.append([])
+        lines[-1].append(byt)
+    return '\n'.join([' '.join(['%02x' % y for y in x]) for x in lines])
+
+def diff(a, b):
+    return '\n'.join(difflib.ndiff(a.splitlines(), b.splitlines()))
+
+# Test serialization / deserialization of a sample object.
+# Depends on the __eq__ method being correct.
+def test_serialization(obj, buf):
+    packed = obj.pack()
+    if packed != buf:
+        a = format_binary(buf)
+        b = format_binary(packed)
+        raise AssertionError("Serialization of %s failed\nExpected:\n%s\nActual:\n%s\nDiff:\n%s" % \
+            (type(obj).__name__, a, b, diff(a, b)))
+    unpacked = type(obj).unpack(buf)
+    if obj != unpacked:
+        a = obj.show()
+        b = unpacked.show()
+        raise AssertionError("Deserialization of %s failed\nExpected:\n%s\nActual:\n%s\nDiff:\n%s" % \
+            (type(obj).__name__, a, b, diff(a, b)))
+
 class TestImports(unittest.TestCase):
     def test_toplevel(self):
         import loxi
@@ -86,6 +116,443 @@
         self.assertTrue(isinstance(l[0], ofp.hello_elem_versionbitmap))
         self.assertTrue(isinstance(l[1], ofp.hello_elem_versionbitmap))
 
+class TestMessages(unittest.TestCase):
+    def test_hello(self):
+        obj = ofp.message.hello(
+            xid=0x12345678,
+            elements=[
+                ofp.hello_elem_versionbitmap(
+                    bitmaps=[ofp.uint32(1), ofp.uint32(2)]),
+                ofp.hello_elem_versionbitmap(
+                    bitmaps=[ofp.uint32(3), ofp.uint32(4)])])
+        buf = ''.join([
+            '\x04', '\x00', # version, type
+            '\x00\x20', # length
+            '\x12\x34\x56\x78', # xid
+            '\x00\x01', # elements[0].type
+            '\x00\x0c', # elements[0].length
+            '\x00\x00\x00\x01', # elements[0].bitmaps[0]
+            '\x00\x00\x00\x02', # elements[0].bitmaps[1]
+            '\x00\x01', # elements[1].type
+            '\x00\x0c', # elements[1].length
+            '\x00\x00\x00\x03', # elements[1].bitmaps[0]
+            '\x00\x00\x00\x04', # elements[1].bitmaps[1]
+        ])
+        test_serialization(obj, buf)
+
+    def test_error(self):
+        obj = ofp.message.error_msg(
+            xid=0x12345678,
+            err_type=ofp.OFPET_BAD_MATCH,
+            code=ofp.OFPBMC_BAD_MASK,
+            data="abc")
+        buf = ''.join([
+            '\x04', '\x01', # version, type
+            '\x00\x0f', # length
+            '\x12\x34\x56\x78', # xid
+            '\x00\x04', # err_type
+            '\x00\x08', # code
+            'abc', # data
+        ])
+        test_serialization(obj, buf)
+
+    def test_echo_request(self):
+        obj = ofp.message.echo_request(
+            xid=0x12345678,
+            data="abc")
+        buf = ''.join([
+            '\x04', '\x02', # version, type
+            '\x00\x0b', # length
+            '\x12\x34\x56\x78', # xid
+            'abc', # data
+        ])
+        test_serialization(obj, buf)
+
+    def test_echo_reply(self):
+        obj = ofp.message.echo_reply(
+            xid=0x12345678,
+            data="abc")
+        buf = ''.join([
+            '\x04', '\x03', # version, type
+            '\x00\x0b', # length
+            '\x12\x34\x56\x78', # xid
+            'abc', # data
+        ])
+        test_serialization(obj, buf)
+
+    def test_features_request(self):
+        obj = ofp.message.features_request(xid=0x12345678)
+        buf = ''.join([
+            '\x04', '\x05', # version, type
+            '\x00\x08', # length
+            '\x12\x34\x56\x78', # xid
+        ])
+        test_serialization(obj, buf)
+
+    def test_features_reply(self):
+        obj = ofp.message.features_reply(
+            xid=0x12345678,
+            datapath_id=0xFEDCBA9876543210,
+            n_buffers=64,
+            n_tables=200,
+            auxiliary_id=5,
+            capabilities=ofp.OFPC_FLOW_STATS|ofp.OFPC_PORT_BLOCKED,
+            reserved=0)
+        buf = ''.join([
+            '\x04', '\x06', # version, type
+            '\x00\x20', # length
+            '\x12\x34\x56\x78', # xid
+            '\xfe\xdc\xba\x98\x76\x54\x32\x10', # datapath_id
+            '\x00\x00\x00\x40', # n_buffers
+            '\xc8', # n_tables
+            '\x05', # auxiliary_id
+            '\x00\x00', # pad
+            '\x00\x00\x01\x01', # capabilities
+            '\x00\x00\x00\x00', # reserved
+        ])
+        test_serialization(obj, buf)
+
+    def test_get_config_request(self):
+        obj = ofp.message.get_config_request(xid=0x12345678)
+        buf = ''.join([
+            '\x04', '\x07', # version, type
+            '\x00\x08', # length
+            '\x12\x34\x56\x78', # xid
+        ])
+        test_serialization(obj, buf)
+
+    def test_get_config_reply(self):
+        obj = ofp.message.get_config_reply(
+            xid=0x12345678,
+            flags=ofp.OFPC_FRAG_REASM,
+            miss_send_len=0xffff)
+        buf = ''.join([
+            '\x04', '\x08', # version, type
+            '\x00\x0c', # length
+            '\x12\x34\x56\x78', # xid
+            '\x00\x02', # flags
+            '\xff\xff', # miss_send_len
+        ])
+        test_serialization(obj, buf)
+
+    def test_set_config(self):
+        obj = ofp.message.set_config(
+            xid=0x12345678,
+            flags=ofp.OFPC_FRAG_REASM,
+            miss_send_len=0xffff)
+        buf = ''.join([
+            '\x04', '\x09', # version, type
+            '\x00\x0c', # length
+            '\x12\x34\x56\x78', # xid
+            '\x00\x02', # flags
+            '\xff\xff', # miss_send_len
+        ])
+        test_serialization(obj, buf)
+
+    def test_packet_in(self):
+        obj = ofp.message.packet_in(
+            xid=0x12345678,
+            buffer_id=100,
+            total_len=17000,
+            reason=ofp.OFPR_ACTION,
+            table_id=20,
+            cookie=0xFEDCBA9876543210,
+            match=ofp.match(oxm_list=[
+                ofp.oxm.arp_op(value=1),
+                ofp.oxm.in_port_masked(value=4, value_mask=5)]),
+            data="abc")
+        buf = ''.join([
+            '\x04', '\x0a', # version, type
+            '\x00\x35', # length
+            '\x12\x34\x56\x78', # xid
+            '\x00\x00\x00\x64', # buffer_id
+            '\x42\x68', # total_len
+            '\x01', # reason
+            '\x14', # table_id
+            '\xfe\xdc\xba\x98\x76\x54\x32\x10', # cookie
+            '\x00\x01', # match.type
+            '\x00\x16', # match.length
+            '\x80\x00\x2A\x02', # match.oxm_list[0].type_len
+            '\x00\x01', # match.oxm_list[0].value
+            '\x80\x00\x01\x08', # match.oxm_list[1].type_len
+            '\x00\x00\x00\x04', # match.oxm_list[1].value
+            '\x00\x00\x00\x05', # match.oxm_list[1].mask
+            '\x00\x00', # match.pad
+            '\x00\x00', # pad
+            'abc', # data
+        ])
+        test_serialization(obj, buf)
+
+    def test_flow_removed(self):
+        obj = ofp.message.flow_removed(
+            xid=0x12345678,
+            cookie=0xFEDCBA9876543210,
+            priority=17000,
+            reason=ofp.OFPRR_DELETE,
+            table_id=20,
+            duration_sec=10,
+            duration_nsec=1000,
+            idle_timeout=5,
+            hard_timeout=30,
+            packet_count=1,
+            byte_count=2,
+            match=ofp.match(oxm_list=[
+                ofp.oxm.arp_op(value=1),
+                ofp.oxm.in_port_masked(value=4, value_mask=5)]))
+        buf = ''.join([
+            '\x04', '\x0b', # version, type
+            '\x00\x48', # length
+            '\x12\x34\x56\x78', # xid
+            '\xfe\xdc\xba\x98\x76\x54\x32\x10', # cookie
+            '\x42\x68', # priority
+            '\x02', # reason
+            '\x14', # table_id
+            '\x00\x00\x00\x0a', # duration_sec
+            '\x00\x00\x03\xe8', # duration_nsec
+            '\x00\x05', # idle_timeout
+            '\x00\x1e', # hard_timeout
+            '\x00\x00\x00\x00\x00\x00\x00\x01', # packet_count
+            '\x00\x00\x00\x00\x00\x00\x00\x02', # byte_count
+            '\x00\x01', # match.type
+            '\x00\x16', # match.length
+            '\x80\x00\x2A\x02', # match.oxm_list[0].type_len
+            '\x00\x01', # match.oxm_list[0].value
+            '\x80\x00\x01\x08', # match.oxm_list[1].type_len
+            '\x00\x00\x00\x04', # match.oxm_list[1].value
+            '\x00\x00\x00\x05', # match.oxm_list[1].mask
+            '\x00\x00', # match.pad
+        ])
+        test_serialization(obj, buf)
+
+    def test_port_status(self):
+        obj = ofp.message.port_status(
+            xid=0x12345678,
+            reason=ofp.OFPPR_MODIFY,
+            desc=ofp.port_desc(
+                port_no=4,
+                hw_addr=[1,2,3,4,5,6],
+                name="foo",
+                config=ofp.OFPPC_NO_FWD|ofp.OFPPC_NO_RECV,
+                state=ofp.OFPPS_BLOCKED,
+                curr=ofp.OFPPF_10MB_HD,
+                advertised=ofp.OFPPF_10MB_FD,
+                supported=ofp.OFPPF_100MB_HD,
+                peer=ofp.OFPPF_100MB_FD,
+                curr_speed=10,
+                max_speed=20))
+        buf = ''.join([
+            '\x04', '\x0c', # version, type
+            '\x00\x50', # length
+            '\x12\x34\x56\x78', # xid
+            '\x02', # reason
+            '\x00' * 7, # pad
+            '\x00\x00\x00\x04', # port_no
+            '\x00' * 4, # pad
+            '\x01\x02\x03\x04\x05\x06', # hw_addr
+            '\x00' * 2, # pad
+            'foo' + '\x00' * 13, # name
+            '\x00\x00\x00\x24', # config
+            '\x00\x00\x00\x02', # state
+            '\x00\x00\x00\x01', # curr
+            '\x00\x00\x00\x02', # advertised
+            '\x00\x00\x00\x04', # supported
+            '\x00\x00\x00\x08', # peer
+            '\x00\x00\x00\x0a', # curr_speed
+            '\x00\x00\x00\x14', # max_speed
+        ])
+        test_serialization(obj, buf)
+
+    def test_packet_out(self):
+        # TODO
+        pass
+
+
+    ## Flow-mods
+
+    def test_flow_add(self):
+        # TODO
+        pass
+
+    def test_flow_modify(self):
+        # TODO
+        pass
+
+    def test_flow_modify_strict(self):
+        # TODO
+        pass
+
+    def test_flow_delete(self):
+        # TODO
+        pass
+
+    def test_flow_delete_strict(self):
+        # TODO
+        pass
+
+
+    def test_group_mod(self):
+        # TODO
+        pass
+
+    def test_port_mod(self):
+        # TODO
+        pass
+
+    def test_table_mod(self):
+        # TODO
+        pass
+
+
+    ## Multipart messages
+
+    def test_desc_stats_request(self):
+        # TODO
+        pass
+
+    def test_desc_stats_reply(self):
+        # TODO
+        pass
+
+    def test_flow_stats_request(self):
+        # TODO
+        pass
+
+    def test_flow_stats_reply(self):
+        # TODO
+        pass
+
+    def test_aggregate_stats_request(self):
+        # TODO
+        pass
+
+    def test_aggregate_stats_reply(self):
+        # TODO
+        pass
+
+    def test_port_stats_request(self):
+        # TODO
+        pass
+
+    def test_port_stats_reply(self):
+        # TODO
+        pass
+
+    def test_queue_stats_request(self):
+        # TODO
+        pass
+
+    def test_queue_stats_reply(self):
+        # TODO
+        pass
+
+    def test_group_stats_request(self):
+        # TODO
+        pass
+
+    def test_group_stats_reply(self):
+        # TODO
+        pass
+
+    def test_group_desc_stats_request(self):
+        # TODO
+        pass
+
+    def test_group_desc_stats_reply(self):
+        # TODO
+        pass
+
+    def test_group_features_stats_request(self):
+        # TODO
+        pass
+
+    def test_group_features_stats_reply(self):
+        # TODO
+        pass
+
+    def test_meter_stats_request(self):
+        # TODO
+        pass
+
+    def test_meter_stats_reply(self):
+        # TODO
+        pass
+
+    def test_meter_config_stats_request(self):
+        # TODO
+        pass
+
+    def test_meter_config_stats_reply(self):
+        # TODO
+        pass
+
+    def test_meter_features_stats_request(self):
+        # TODO
+        pass
+
+    def test_meter_features_stats_reply(self):
+        # TODO
+        pass
+
+    def test_table_features_stats_request(self):
+        # TODO
+        pass
+
+    def test_table_features_stats_reply(self):
+        # TODO
+        pass
+
+    def test_port_desc_stats_request(self):
+        # TODO
+        pass
+
+    def test_port_desc_stats_reply(self):
+        # TODO
+        pass
+
+
+    def test_barrier_request(self):
+        # TODO
+        pass
+
+    def test_barrier_reply(self):
+        # TODO
+        pass
+
+    def test_queue_get_config_request(self):
+        # TODO
+        pass
+
+    def test_queue_get_config_reply(self):
+        # TODO
+        pass
+
+    def test_role_request(self):
+        # TODO
+        pass
+
+    def test_role_reply(self):
+        # TODO
+        pass
+
+    def test_get_async_request(self):
+        # TODO
+        pass
+
+    def test_get_async_reply(self):
+        # TODO
+        pass
+
+    def test_set_async(self):
+        # TODO
+        pass
+
+    def test_meter_mod(self):
+        # TODO
+        pass
+
+    # TODO test experimenter messages
+
+
 class TestOXM(unittest.TestCase):
     def test_oxm_in_phy_port_pack(self):
         import loxi.of13 as ofp