Test: Add coverage for Offers and Refunds without blinded paths

Introduced tests to validate the behavior of Offers and Refunds
created without blinded paths, using `NullMessageRouter`.

Author: shaavan

lightning/src/ln/offers_tests.rs

@@ -60,7 +60,7 @@ use crate::offers::invoice_error::InvoiceError;
 use crate::offers::invoice_request::{InvoiceRequest, InvoiceRequestFields};
 use crate::offers::nonce::Nonce;
 use crate::offers::parse::Bolt12SemanticError;
-use crate::onion_message::messenger::{Destination, MessageSendInstructions, NodeIdMessageRouter, PeeledOnion};
+use crate::onion_message::messenger::{Destination, MessageSendInstructions, NodeIdMessageRouter, NullMessageRouter, PeeledOnion};
 use crate::onion_message::offers::OffersMessage;
 use crate::routing::gossip::{NodeAlias, NodeId};
 use crate::routing::router::{PaymentParameters, RouteParameters, RouteParametersConfig};
@@ -265,6 +265,55 @@ fn extract_invoice_error<'a, 'b, 'c>(
 	}
 }
 
+/// Checks that an offer can be created with no blinded paths.
+#[test]
+fn create_offer_with_no_blinded_path() {
+	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]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 1_000_000_000);
+
+	let alice = &nodes[0];
+	let alice_id = alice.node.get_our_node_id();
+
+	let router = NullMessageRouter {};
+	let offer = alice.node
+		.create_offer_builder_using_router(&router).unwrap()
+		.amount_msats(10_000_000)
+		.build().unwrap();
+	assert_eq!(offer.issuer_signing_pubkey(), Some(alice_id));
+	assert!(offer.paths().is_empty());
+}
+
+/// Checks that a refund can be created with no blinded paths.
+#[test]
+fn create_refund_with_no_blinded_path() {
+	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]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 1_000_000_000);
+
+	let alice = &nodes[0];
+	let alice_id = alice.node.get_our_node_id();
+
+	let absolute_expiry = Duration::from_secs(u64::MAX);
+	let payment_id = PaymentId([1; 32]);
+
+	let router = NullMessageRouter {};
+	let refund = alice.node
+		.create_refund_builder_using_router(&router, 10_000_000, absolute_expiry, payment_id, Retry::Attempts(0), RouteParametersConfig::default())
+		.unwrap()
+		.build().unwrap();
+	assert_eq!(refund.amount_msats(), 10_000_000);
+	assert_eq!(refund.absolute_expiry(), Some(absolute_expiry));
+	assert_eq!(refund.payer_signing_pubkey(), alice_id);
+	assert!(refund.paths().is_empty());
+}
+
 /// Checks that blinded paths without Tor-only nodes are preferred when constructing an offer.
 #[test]
 fn prefers_non_tor_nodes_in_blinded_paths() {