test utils: add optional PaymentPreimage param to pass_along_path

This will allow keysend tests to assert that the PaymentReceived payment preimage is
as expected in upcoming commits.

Author: valentinewallace

lightning/src/ln/chanmon_update_fail_tests.rs

@@ -2039,15 +2039,15 @@ fn test_path_paused_mpp() {
 	// Pass the first HTLC of the payment along to nodes[3].
 	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 	assert_eq!(events.len(), 1);
-	pass_along_path(&nodes[0], &[&nodes[1], &nodes[3]], 0, payment_hash.clone(), payment_secret, events.pop().unwrap(), false);
+	pass_along_path(&nodes[0], &[&nodes[1], &nodes[3]], 0, payment_hash.clone(), payment_secret, events.pop().unwrap(), false, None);
 
 	// And check that, after we successfully update the monitor for chan_2 we can pass the second
 	// HTLC along to nodes[3] and claim the whole payment back to nodes[0].
 	let (outpoint, latest_update) = nodes[0].chain_monitor.latest_monitor_update_id.lock().unwrap().get(&chan_2_id).unwrap().clone();
 	nodes[0].node.channel_monitor_updated(&outpoint, latest_update);
 	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 	assert_eq!(events.len(), 1);
-	pass_along_path(&nodes[0], &[&nodes[2], &nodes[3]], 200_000, payment_hash.clone(), payment_secret, events.pop().unwrap(), true);
+	pass_along_path(&nodes[0], &[&nodes[2], &nodes[3]], 200_000, payment_hash.clone(), payment_secret, events.pop().unwrap(), true, None);
 
 	claim_payment_along_route(&nodes[0], &[&[&nodes[1], &nodes[3]], &[&nodes[2], &nodes[3]]], false, payment_preimage);
 }

lightning/src/ln/functional_test_utils.rs

@@ -1056,7 +1056,7 @@ pub fn send_along_route_with_secret<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>,
 	pass_along_route(origin_node, expected_paths, recv_value, our_payment_hash, our_payment_secret);
 }
 
-pub fn pass_along_path<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_path: &[&Node<'a, 'b, 'c>], recv_value: u64, our_payment_hash: PaymentHash, our_payment_secret: PaymentSecret, ev: MessageSendEvent, payment_received_expected: bool) {
+pub fn pass_along_path<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_path: &[&Node<'a, 'b, 'c>], recv_value: u64, our_payment_hash: PaymentHash, our_payment_secret: PaymentSecret, ev: MessageSendEvent, payment_received_expected: bool, expected_preimage: Option<PaymentPreimage>) {
 	let mut payment_event = SendEvent::from_event(ev);
 	let mut prev_node = origin_node;
 
@@ -1078,7 +1078,7 @@ pub fn pass_along_path<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_path
 						assert_eq!(our_payment_hash, *payment_hash);
 						match &purpose {
 							PaymentPurpose::InvoicePayment { payment_preimage, payment_secret, .. } => {
-								assert!(payment_preimage.is_none());
+								assert_eq!(expected_preimage, *payment_preimage);
 								assert_eq!(our_payment_secret, *payment_secret);
 							},
 							_ => {},
@@ -1109,7 +1109,7 @@ pub fn pass_along_route<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_rou
 		// Once we've gotten through all the HTLCs, the last one should result in a
 		// PaymentReceived (but each previous one should not!), .
 		let expect_payment = path_idx == expected_route.len() - 1;
-		pass_along_path(origin_node, expected_path, recv_value, our_payment_hash.clone(), our_payment_secret, ev, expect_payment);
+		pass_along_path(origin_node, expected_path, recv_value, our_payment_hash.clone(), our_payment_secret, ev, expect_payment, None);
 	}
 }
 

lightning/src/ln/functional_tests.rs

@@ -4197,7 +4197,7 @@ fn do_test_htlc_timeout(send_partial_mpp: bool) {
 		assert_eq!(events.len(), 1);
 		// Now do the relevant commitment_signed/RAA dances along the path, noting that the final
 		// hop should *not* yet generate any PaymentReceived event(s).
-		pass_along_path(&nodes[0], &[&nodes[1]], 100000, our_payment_hash, payment_secret, events.drain(..).next().unwrap(), false);
+		pass_along_path(&nodes[0], &[&nodes[1]], 100000, our_payment_hash, payment_secret, events.drain(..).next().unwrap(), false, None);
 		our_payment_hash
 	} else {
 		route_payment(&nodes[0], &[&nodes[1]], 100000).1