test_lnwallet: add unittest for single channel mpp split config
What the developer wrote
Authored by f321x
test_lnwallet: add unittest for single channel mpp split config
Tests that all parts of a multi-part payment over a single channel
are constructed using the channel of the split configuration.
What changed, and why it matters
This commit adds a new automated test to the Electrum project. It does not change any production wallet or Lightning code. The test verifies that when Electrum splits a multi-part payment across a single channel, all payment parts actually use that chosen channel rather than letting the pathfinder pick a different cheaper route. It is purely a test-case addition.
No security action needed. Review as normal test-code quality if desired.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The diff adds one unit test, test_payment_multipart_single_channel_split, to tests/test_lnwallet.py. The test sets up a square Lightning graph, prepares an invoice from Dave, forces Alice’s wallet to suggest a SplitConfig that places two equal payment parts on the Alice→Bob channel, and then checks that create_routes_from_invoice returns exactly two routes whose first hop is that Alice→Bob channel. No library or runtime behavior is modified; only test coverage is added.
Changed components
tests/test_lnwallet.pyInspect captured patch +22 / −0
diff --git a/tests/test_lnwallet.py b/tests/test_lnwallet.py
index 4c3919f..e5dcf87 100644
--- a/tests/test_lnwallet.py
+++ b/tests/test_lnwallet.py
@@ -15,6 +15,7 @@ from electrum.invoices import LN_EXPIRY_NEVER, PR_UNPAID
from electrum.lnpeer import Peer
from electrum.lnchannel import Channel, ChannelState
from electrum.lnonion import OnionPacket, OnionRoutingFailure
+from electrum.mpp_split import SplitConfig, SplitConfigRating
from electrum.crypto import sha256
from electrum.simple_config import SimpleConfig
@@ -474,3 +475,24 @@ class TestLNWallet(ElectrumTestCase):
chan1.set_frozen_for_sending(True) # shouldn't matter, this channel will receive
success, log = await alice.rebalance_channels(chan0, chan1, amount_msat=150_000_000)
self.assertTrue(success, msg=log)
+
+ async def test_payment_multipart_single_channel_split(self):
+ """A split configuration can put multiple parts on a single channel. The parts
+ must then be sent over that channel, instead of the pathfinder freely choosing
+ a first hop, which would ignore the balance allocation of the config."""
+ graph = lnhelpers.prepare_chans_and_peers_in_graph(self, lnhelpers._GRAPH_DEFINITIONS['square_graph'])
+ alice_w, dave_w = graph.workers['alice'], graph.workers['dave']
+ dave_w.features |= LnFeatures.BASIC_MPP_OPT
+ self.assertFalse(alice_w.uses_trampoline())
+ amount_to_pay = 200_000_000
+ lnaddr, _pay_req = lnhelpers.prepare_invoice(dave_w, include_routing_hints=True, amount_msat=amount_to_pay)
+ # force a split config with two parts on the high-fee alice-bob channel,
+ # although the pathfinder considers the route via carol cheaper
+ bob_chan = graph.channels[('alice', 'bob')][0]
+ split_config = SplitConfig({(bob_chan.channel_id, bob_chan.node_id): [amount_to_pay // 2, amount_to_pay // 2]})
+ alice_w.suggest_payment_splits = lambda **kwargs: [SplitConfigRating(config=split_config, rating=0)]
+ routes = await alice_w.create_routes_from_invoice(amount_to_pay, decoded_invoice=lnaddr)
+ self.assertEqual(2, len(routes))
+ for shi, _, _ in routes:
+ # all constructed routes use the outgoing channel of the split config
+ self.assertEqual(bob_chan.short_channel_id, shi.route[0].short_channel_id)
Why this scored 15/100
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