[wip] Add multihop correctness test for correct_inflight_map_from_path

lightning-invoice/src/payment.rs

@@ -682,8 +682,8 @@ where
 				// hardcoded with an inflight value of 0 so that we can correctly represent the first hop
 				// in our sliding window of two.
 				let our_node_id: PublicKey = self.payer.node_id();
-				let reversed_hops_with_payer = core::iter::once((0u64, our_node_id)).chain(
-					path.split_last().unwrap().1.iter().map(|hop| (hop.fee_msat, hop.pubkey))).rev();
+				let reversed_hops_with_payer: Vec<(u64, PublicKey)> = core::iter::once((0u64, our_node_id)).chain(
+					path.split_last().unwrap().1.iter().map(|hop| (hop.fee_msat, hop.pubkey))).rev().collect();
 				let mut cumulative_msat = path.last().unwrap().fee_msat;
 
 				// Taking the reversed vector from above, we zip it with just the reversed hops list to
@@ -1555,6 +1555,32 @@ mod tests {
 		invoice_payer.handle_event(&event);
 	}
 
+	#[test]
+	fn correct_inflight_map_from_path() {
+		let event_handled = core::cell::RefCell::new(false);
+		let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
+
+		let final_value_msat = 128u64;
+		let payer = TestPayer::new()
+			.expect_send(Amount::ForInvoice(final_value_msat));
+		let router = TestMultiHopRouter {};
+		let scorer = RefCell::new(TestScorer::new());
+		let logger = TestLogger::new();
+		let invoice_payer =
+			InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, Retry::Attempts(2));
+
+		let payment_preimage = PaymentPreimage([1; 32]);
+		let invoice = invoice(payment_preimage);
+		let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
+
+		let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
+
+		let inflight_map = invoice_payer.create_inflight_map(&payment_hash);
+		assert_eq!(inflight_map.get(&(0u64, true)).unwrap().clone(), 158u64);
+		assert_eq!(inflight_map.get(&(1u64, true)).unwrap().clone(), 148u64);
+		assert_eq!(inflight_map.get(&(2u64, true)).unwrap().clone(), 128u64);
+	}
+
 	struct TestRouter;
 
 	impl TestRouter {
@@ -1620,6 +1646,55 @@ mod tests {
 		}
 	}
 
+	struct TestMultiHopRouter;
+
+	impl TestMultiHopRouter {
+		// Constructs the following route:
+		// Alice -(0,10)-> Bob -(0, 20)-> Charlie -(0, 130)-> Dina
+		fn route_for_value(final_value_msat: u64) -> Route {
+			Route {
+				paths: vec![vec![
+					RouteHop{
+						pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+						channel_features: ChannelFeatures::empty(),
+						node_features: NodeFeatures::empty(),
+						short_channel_id: 0,
+						fee_msat: 10,
+						cltv_expiry_delta: 0
+					},
+					RouteHop{
+						pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+						channel_features: ChannelFeatures::empty(),
+						node_features: NodeFeatures::empty(),
+						short_channel_id: 1,
+						fee_msat: 20,
+						cltv_expiry_delta: 0
+					},
+					RouteHop{
+						pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
+						channel_features: ChannelFeatures::empty(),
+						node_features: NodeFeatures::empty(),
+						short_channel_id: 2,
+						fee_msat: final_value_msat,
+						cltv_expiry_delta: 0
+					},
+				]],
+				payment_params: None,
+			}
+		}
+	}
+
+	impl Router for TestMultiHopRouter {
+		fn find_route<S: Score>(
+			&self, _payer: &PublicKey, route_params: &RouteParameters, _payment_hash: &PaymentHash,
+			_first_hops: Option<&[&ChannelDetails]>, _scorer: &S
+		) -> Result<Route, LightningError> {
+			Ok(Route {
+				payment_params: Some(route_params.payment_params.clone()), ..Self::route_for_value(route_params.final_value_msat)
+			})
+		}
+	}
+
 	struct TestScorer {
 		expectations: Option<VecDeque<TestResult>>,
 	}