Add NetworkGraph persistence error test

Author: jurvis

lightning-background-processor/src/lib.rs

@@ -681,6 +681,46 @@ mod tests {
 		}
 	}
 
+	#[test]
+	fn test_network_graph_persist_error() {
+		// Test that if we encounter an error during network graph persistence, an error gets returned.
+		let nodes = create_nodes(2, "test_persist_network_graph_error".to_string());
+		open_channel!(nodes[0], nodes[1], 100000);
+
+		struct NetworkGraphErrorPersister {
+			data_dir: String,
+		}
+
+		impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L:Deref> super::Persister<Signer, M, T, K, F, L> for NetworkGraphErrorPersister where
+			M::Target: 'static + chain::Watch<Signer>,
+			T::Target: 'static + BroadcasterInterface,
+			K::Target: 'static + KeysInterface<Signer = Signer>,
+			F::Target: 'static + FeeEstimator,
+			L::Target: 'static + Logger,
+		{
+			fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error> {
+				FilesystemPersister::persist_manager(self.data_dir.clone(), channel_manager)
+			}
+
+			fn persist_graph(&self, _network_graph: &NetworkGraph) -> Result<(), std::io::Error> {
+				Err(std::io::Error::new(std::io::ErrorKind::Other, "test"))
+			}
+		}
+
+		let data_dir = nodes[0].persister.get_data_dir();
+		let persister = NetworkGraphErrorPersister { data_dir };
+		let event_handler = |_: &_| {};
+		let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].chain_monitor.clone(), nodes[0].node.clone(), nodes[0].net_graph_msg_handler.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
+
+		match bg_processor.stop() {
+			Ok(_) => panic!("Expected error persisting network graph"),
+			Err(e) => {
+				assert_eq!(e.kind(), std::io::ErrorKind::Other);
+				assert_eq!(e.get_ref().unwrap().to_string(), "test");
+			},
+		}
+	}
+
 	#[test]
 	fn test_background_event_handling() {
 		let mut nodes = create_nodes(2, "test_background_event_handling".to_string());