Add functional test for using an override config when creating a channel

Author: ccdle12

lightning/src/ln/functional_tests.rs

@@ -7298,3 +7298,21 @@ fn test_bump_txn_sanitize_tracking_maps() {
 		}
 	}
 }
+
+#[test]
+fn test_override_channel_config() {
+    let node_cfgs = create_node_cfgs(2);
+    let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+    let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+    // Node0 initiates a channel to node1 using the override config.
+    let mut override_config = UserConfig::default();
+    override_config.own_channel_config.our_to_self_delay = 200;
+
+    nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 16_000_000, 12_000_000, 42, Some(override_config)).unwrap();
+
+    // Assert the channel created by node0 is using the override config.
+    let res = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
+    assert_eq!(res.channel_flags, 0);
+    assert_eq!(res.to_self_delay, 200);
+}