Add integration test for InvoicePayerretry on an immediate failure

Author: TheBlueMatt

lightning-invoice/src/payment.rs

@@ -1246,4 +1246,50 @@ mod tests {
 		check_added_monitors!(nodes[0], 2);
 		assert!(!*event_handled.borrow());
 	}
+
+	#[test]
+	fn immediate_retry_on_failure() {
+		// Tests that we can/will retry immediately after a failure
+		let chanmon_cfgs = create_chanmon_cfgs(2);
+		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
+		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+		create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
+		create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
+		let chans = nodes[0].node.list_usable_channels();
+		let mut route = Route {
+			paths: vec![
+				vec![RouteHop {
+					pubkey: nodes[1].node.get_our_node_id(),
+					node_features: NodeFeatures::known(),
+					short_channel_id: chans[0].short_channel_id.unwrap(),
+					channel_features: ChannelFeatures::known(),
+					fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value
+					cltv_expiry_delta: 100,
+				}],
+			],
+			payee: Some(Payee::new(nodes[1].node.get_our_node_id())),
+		};
+		let mut routes = LinkedList::new();
+		routes.push_back(Ok(route.clone()));
+		// On retry, split the payment across both channels.
+		route.paths.push(route.paths[0].clone());
+		route.paths[0][0].short_channel_id = chans[1].short_channel_id.unwrap();
+		route.paths[0][0].fee_msat = 50_000_000;
+		route.paths[1][0].fee_msat = 50_000_001;
+		routes.push_back(Ok(route.clone()));
+		let route_res = ManualRouter(Mutex::new(routes));
+
+		let event_handled = core::cell::RefCell::new(false);
+		let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
+		let invoice_payer = InvoicePayer::new(nodes[0].node, route_res, nodes[0].logger, event_handler, RetryAttempts(1));
+
+		invoice_payer.pay_invoice(&create_invoice_from_channelmanager(
+			&nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string()).unwrap()).unwrap();
+		let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
+		assert_eq!(htlc_msgs.len(), 2);
+		check_added_monitors!(nodes[0], 2);
+		assert!(!*event_handled.borrow());
+	}
 }