Add a hop to rust-lightning test

gistfile1.txt

#[test]
fn test_onchain_to_onchain_claim() {
	// Test that in case of channel closure, we detect the state of output and claim HTLC
	// on downstream peer's remote commitment tx.
	// First, have C claim an HTLC against its own latest commitment transaction.
	// Then, broadcast these to B, which should update the monitor downstream on the A<->B
	// channel.
	// Finally, check that B will claim the HTLC output if A's latest commitment transaction
	// gets broadcast.

	let chanmon_cfgs = create_chanmon_cfgs(4);
	let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
	let nodes = create_network(4, &node_cfgs, &node_chanmgrs);

	// Create some initial channels
	let chan_1 = create_announced_chan_between_nodes(&nodes, 0, 1);
	let chan_2 = create_announced_chan_between_nodes(&nodes, 1, 2);
	let chan_3 = create_announced_chan_between_nodes(&nodes, 2, 3);

	// Ensure all nodes are at the same height
	let node_max_height = nodes.iter().map(|node| node.blocks.lock().unwrap().len()).max().unwrap() as u32;
	connect_blocks(&nodes[0], node_max_height - nodes[0].best_block_info().1);
	connect_blocks(&nodes[1], node_max_height - nodes[1].best_block_info().1);
	connect_blocks(&nodes[2], node_max_height - nodes[2].best_block_info().1);
	connect_blocks(&nodes[3], node_max_height - nodes[3].best_block_info().1);

	// Rebalance the network a bit by relaying one payment through all the channels ...
	send_payment(&nodes[0], &vec!(&nodes[1], &nodes[2], &nodes[3])[..], 8000000);
	send_payment(&nodes[0], &vec!(&nodes[1], &nodes[2], &nodes[3])[..], 8000000);

	let (payment_preimage, payment_hash, _payment_secret) = route_payment(&nodes[0], &[&nodes[1], &nodes[2], &nodes[3]], 3_000_000);
	let commitment_tx = get_local_commitment_txn!(nodes[3], chan_3.2);
	check_spends!(commitment_tx[0], chan_3.3);
	nodes[3].node.claim_funds(payment_preimage);
	expect_payment_claimed!(nodes[3], payment_hash, 3_000_000);
	check_added_monitors!(nodes[3], 1);
	let updates = get_htlc_update_msgs!(nodes[3], nodes[2].node.get_our_node_id());
	assert!(updates.update_add_htlcs.is_empty());
	assert!(updates.update_fail_htlcs.is_empty());
	assert_eq!(updates.update_fulfill_htlcs.len(), 1);
	assert!(updates.update_fail_malformed_htlcs.is_empty());

	mine_transaction(&nodes[3], &commitment_tx[0]);
	check_closed_broadcast!(nodes[3], true);
	check_added_monitors!(nodes[3], 1);
	check_closed_event!(nodes[3], 1, ClosureReason::CommitmentTxConfirmed);

	let c_txn = nodes[3].tx_broadcaster.txn_broadcasted.lock().unwrap().clone(); // ChannelMonitor: 1 (HTLC-Success tx)
	assert_eq!(c_txn.len(), 1);
	check_spends!(c_txn[0], commitment_tx[0]);
	assert_eq!(c_txn[0].input[0].witness.clone().last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT);
	assert!(c_txn[0].output[0].script_pubkey.is_v0_p2wsh()); // revokeable output
	assert_eq!(c_txn[0].lock_time.0, 0); // Success tx

	// So we broadcast C's commitment tx and HTLC-Success on B's chain, we should successfully be able to extract preimage and update downstream monitor
	let header = BlockHeader { version: 0x20000000, prev_blockhash: nodes[2].best_block_hash(), merkle_root: TxMerkleNode::all_zeros(), time: 42, bits: 42, nonce: 42};
	connect_block(&nodes[2], &Block { header, txdata: vec![commitment_tx[0].clone(), c_txn[0].clone()]});
	check_added_monitors!(nodes[2], 1);
	let events = nodes[2].node.get_and_clear_pending_events();
	assert_eq!(events.len(), 2);
	match events[0] {
		Event::ChannelClosed { reason: ClosureReason::CommitmentTxConfirmed, .. } => {}
		_ => panic!("Unexpected event"),
	}
	match events[1] {
		Event::PaymentForwarded { fee_earned_msat, prev_channel_id, claim_from_onchain_tx, next_channel_id } => {
			assert_eq!(fee_earned_msat, Some(1000));
			assert_eq!(prev_channel_id, Some(chan_2.2));
			assert_eq!(claim_from_onchain_tx, true);
			assert_eq!(next_channel_id, Some(chan_3.2));
		},
		_ => panic!("Unexpected event"),
	}
	check_added_monitors!(nodes[2], 1);
	let mut msg_events = nodes[2].node.get_and_clear_pending_msg_events();
	assert_eq!(msg_events.len(), 3);
	let nodes_3_event = remove_first_msg_event_to_node(&nodes[3].node.get_our_node_id(), &mut msg_events);
	let nodes_1_event = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut msg_events);

	match nodes_3_event {
		MessageSendEvent::HandleError { action: ErrorAction::SendErrorMessage { .. }, node_id: _ } => {},
		_ => panic!("Unexpected event"),
	}

	match nodes_1_event {
		MessageSendEvent::UpdateHTLCs { ref node_id, updates: msgs::CommitmentUpdate { ref update_add_htlcs, ref update_fulfill_htlcs, ref update_fail_htlcs, ref update_fail_malformed_htlcs, .. } } => {
			assert!(update_add_htlcs.is_empty());
			assert!(update_fail_htlcs.is_empty());
			assert_eq!(update_fulfill_htlcs.len(), 1);
			assert!(update_fail_malformed_htlcs.is_empty());
			assert_eq!(nodes[1].node.get_our_node_id(), *node_id);
		},
		_ => panic!("Unexpected event"),
	};

	// Ensure that the last remaining message event is the BroadcastChannelUpdate msg for chan_2
	match msg_events[0] {
		MessageSendEvent::BroadcastChannelUpdate { .. } => {},
		_ => panic!("Unexpected event"),
	}

	// Broadcast A's commitment tx on B's chain to see if we are able to claim inbound HTLC with our HTLC-Success tx
	let commitment_tx = get_local_commitment_txn!(nodes[1], chan_2.2);
	mine_transaction(&nodes[2], &commitment_tx[0]);
	check_closed_event!(nodes[2], 1, ClosureReason::CommitmentTxConfirmed);
	let b_txn = nodes[2].tx_broadcaster.txn_broadcasted.lock().unwrap().clone();
	// ChannelMonitor: HTLC-Success tx
	assert_eq!(b_txn.len(), 1);
	check_spends!(b_txn[0], commitment_tx[0]);
	assert_eq!(b_txn[0].input[0].witness.clone().last().unwrap().len(), OFFERED_HTLC_SCRIPT_WEIGHT);
	assert!(b_txn[0].output[0].script_pubkey.is_v0_p2wpkh()); // direct payment
	assert_eq!(b_txn[0].lock_time.0, 0); // Success tx

	check_closed_broadcast!(nodes[2], true);
	check_added_monitors!(nodes[2], 1);
}