f more test docs

Author: TheBlueMatt

lightning/src/routing/router.rs

@@ -4074,7 +4074,7 @@ mod tests {
 		// at the very first hop.
 		//
 		// Specifically, this interacted with our "all paths must fund at least 5% of total target"
-		// criteria to cause us to refuse all routes at the last hop hint which would be considered
+		// criterion to cause us to refuse all routes at the last hop hint which would be considered
 		// to only have the remaining to-collect amount in available liquidity.
 		//
 		// This bug appeared in production in some specific channel configurations.
@@ -4149,8 +4149,15 @@ mod tests {
 		// overpay at all.
 		let route = get_route(&our_id, &payee, &network_graph, None, 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
 		assert_eq!(route.paths.len(), 2);
+		// Paths are somewhat randomly ordered, but:
+		// * the first is channel 2 (1 msat fee) -> channel 4 -> channel 42
+		// * the second is channel 1 (0 fee, but 99 sat maximum) -> channel 3 -> channel 42
 		assert_eq!(route.paths[0][0].short_channel_id, 2);
+		assert_eq!(route.paths[0][0].fee_msat, 1);
+		assert_eq!(route.paths[0][2].fee_msat, 1_000);
 		assert_eq!(route.paths[1][0].short_channel_id, 1);
+		assert_eq!(route.paths[1][0].fee_msat, 0);
+		assert_eq!(route.paths[1][2].fee_msat, 99_000);
 		assert_eq!(route.get_total_fees(), 1);
 		assert_eq!(route.get_total_amount(), 100_000);
 	}