Extend test with old serialized updates

We now also check that the serialization format has not changed and
suceed/fail to read the updates depending on whether `htlc_maximum_msat`
is present.

lightning/src/routing/gossip.rs

@@ -2953,7 +2953,6 @@ mod tests {
 		let node_chanmgrs = ::ln::functional_test_utils::create_node_chanmgrs(2, &node_cfgs, &[None, None, None, None]);
 		let nodes = ::ln::functional_test_utils::create_network(2, &node_cfgs, &node_chanmgrs);
 
-		// First make sure we can encode/decode ChannelUpdateInfo.
 		let chan_update_info = ChannelUpdateInfo {
 			last_update: 23,
 			enabled: true,
@@ -2964,17 +2963,23 @@ mod tests {
 			last_update_message: None,
 		};
 
-		let mut buf: Vec<u8> = Vec::new();
-		assert!(chan_update_info.write(&mut buf).is_ok());
+		let mut encoded_chan_update_info: Vec<u8> = Vec::new();
+		assert!(chan_update_info.write(&mut encoded_chan_update_info).is_ok());
 
-		let read_chan_update_info_result: Option<ChannelUpdateInfo> = ::util::ser::MaybeReadable::read(&mut buf.as_slice()).unwrap();
-		if let Some(read_chan_update_info) = read_chan_update_info_result {
-			assert_eq!(chan_update_info, read_chan_update_info);
-		} else {
-			panic!();
-		}
+		// First make sure we can read ChannelUpdateInfos we just wrote
+		let read_chan_update_info: ChannelUpdateInfo = ::util::ser::Readable::read(&mut encoded_chan_update_info.as_slice()).unwrap();
+		assert_eq!(chan_update_info, read_chan_update_info);
+
+		// Check the serialization hasn't changed.
+		let old_chan_update_info_with_some: Vec<u8> = hex::decode("340004000000170201010402002a060800000000000004d2080909000000000000162e0a0d0c00040000000902040000000a0c0100").unwrap();
+		assert_eq!(encoded_chan_update_info, old_chan_update_info_with_some);
 
-		// Then check we can encode/decode ChannelInfo without ChannelUpdateInfo fields present.
+		// Check we fail if htlc_maximum_msat is not present.
+		let old_chan_update_info_with_none: Vec<u8> = hex::decode("2c0004000000170201010402002a060800000000000004d20801000a0d0c00040000000902040000000a0c0100").unwrap();
+		let read_chan_update_info_res: Result<ChannelUpdateInfo, ::ln::msgs::DecodeError> = ::util::ser::Readable::read(&mut old_chan_update_info_with_none.as_slice());
+		assert!(read_chan_update_info_res.is_err());
+
+		// Check we can encode/decode ChannelInfo without ChannelUpdateInfo fields present.
 		let chan_info_none_updates = ChannelInfo {
 			features: ChannelFeatures::known(),
 			node_one: NodeId::from_pubkey(&nodes[0].node.get_our_node_id()),
@@ -2986,10 +2991,10 @@ mod tests {
 			announcement_received_time: 87654,
 		};
 
-		let mut buf: Vec<u8> = Vec::new();
-		assert!(chan_info_none_updates.write(&mut buf).is_ok());
+		let mut encoded_chan_info: Vec<u8> = Vec::new();
+		assert!(chan_info_none_updates.write(&mut encoded_chan_info).is_ok());
 
-		let read_chan_info: ChannelInfo = ::util::ser::Readable::read(&mut buf.as_slice()).unwrap();
+		let read_chan_info: ChannelInfo = ::util::ser::Readable::read(&mut encoded_chan_info.as_slice()).unwrap();
 		assert_eq!(chan_info_none_updates, read_chan_info);
 
 		// Finally check we can encode/decode ChannelInfo with ChannelUpdateInfo fields present.
@@ -3004,10 +3009,10 @@ mod tests {
 			announcement_received_time: 87654,
 		};
 
-		let mut buf: Vec<u8> = Vec::new();
-		assert!(chan_info_some_updates.write(&mut buf).is_ok());
+		let mut encoded_chan_info: Vec<u8> = Vec::new();
+		assert!(chan_info_some_updates.write(&mut encoded_chan_info).is_ok());
 
-		let read_chan_info: ChannelInfo = ::util::ser::Readable::read(&mut buf.as_slice()).unwrap();
+		let read_chan_info: ChannelInfo = ::util::ser::Readable::read(&mut encoded_chan_info.as_slice()).unwrap();
 		assert_eq!(chan_info_some_updates, read_chan_info);
 	}
 }