import random import electrum.mpp_split as mpp_split # side effect for PART_PENALTY from electrum.lnutil import NoPathFound from . import ElectrumTestCase PART_PENALTY = mpp_split.PART_PENALTY class TestMppSplit(ElectrumTestCase): def setUp(self): super().setUp() # to make tests reproducible: random.seed(0) # key tuple denotes (channel_id, node_id) self.channels_with_funds = { (b"0", b"0"): (1_000_000_000, 3), (b"1", b"1"): (500_000_000, 2), (b"2", b"0"): (302_000_000, 2), (b"3", b"2"): (101_000_000, 1), } def tearDown(self): super().tearDown() # undo side effect mpp_split.PART_PENALTY = PART_PENALTY def test_suggest_splits(self): with self.subTest(msg="do a payment with the maximal amount spendable over a single channel"): splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_part_payments=True) self.assertEqual({ (b"0", b"0"): [671_020_676], (b"1", b"1"): [328_979_324], (b"2", b"0"): [], (b"3", b"2"): []}, splits[0].config ) with self.subTest(msg="payment amount that does not require to be split"): splits = mpp_split.suggest_splits(50_000_000, self.channels_with_funds, exclude_single_part_payments=False) self.assertEqual({(b"0", b"0"): [50_000_000]}, splits[0].config) self.assertEqual({(b"1", b"1"): [50_000_000]}, splits[1].config) self.assertEqual({(b"2", b"0"): [50_000_000]}, splits[2].config) self.assertEqual({(b"3", b"2"): [50_000_000]}, splits[3].config) self.assertEqual(2, splits[4].config.number_parts()) with self.subTest(msg="do a payment with a larger amount than what is supported by a single channel"): splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds, exclude_single_part_payments=False) self.assertEqual(2, splits[0].config.number_parts()) with self.subTest(msg="do a payment with the maximal amount spendable over all channels"): splits = mpp_split.suggest_splits( sum([x[0] for x in self.channels_with_funds.values()]), self.channels_with_funds, exclude_single_part_payments=True) self.assertEqual({ (b"0", b"0"): [1_000_000_000], (b"1", b"1"): [500_000_000], (b"2", b"0"): [302_000_000], (b"3", b"2"): [101_000_000]}, splits[0].config ) with self.subTest(msg="do a payment with the amount supported by all channels"): splits = mpp_split.suggest_splits(101_000_000, self.channels_with_funds, exclude_single_part_payments=False) for split in splits[:3]: self.assertEqual(1, split.config.number_nonzero_channels()) # due to exhaustion of the smallest channel, the algorithm favors # a splitting of the parts into two self.assertEqual(2, splits[4].config.number_parts()) with self.subTest(msg="no htlc slots available"): channels = self.channels_with_funds.copy() # set all available slots to 0 for chan, (amount, _slots) in channels.items(): channels[chan] = (amount, 0) with self.assertRaises(NoPathFound): mpp_split.suggest_splits(20_000_000, channels, exclude_single_part_payments=False) with self.subTest(msg="only one channel can add htlcs"): channels = self.channels_with_funds.copy() # set all available slots to 0 except for the first channel for chan, (amount, _slots) in channels.items(): if chan != (b"0", b"0"): channels[chan] = (amount, 0) splits = mpp_split.suggest_splits(1_000_000_000, channels, exclude_single_part_payments=True) for split in splits: # check that the whole amount has been split on this channel self.assertEqual(sum(split.config[(b"0", b"0")]), 1_000_000_000) with self.subTest(msg="test exclude single channel splits"): splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_channel_splits=True) for split in splits: for channel_split in split.config.values(): assert len(channel_split) <= 1, split def test_send_to_single_node(self): splits = mpp_split.suggest_splits(1_000_000_000, self.channels_with_funds, exclude_single_part_payments=False, exclude_multinode_payments=True) for split in splits: assert split.config.number_nonzero_nodes() == 1 def test_saturation(self): """Split configurations which spend the full amount in a channel should be avoided.""" channels_with_funds = { (b"0", b"0"): (159_799_733_076, 1), (b"1", b"1"): (499_986_152_000, 1) } splits = mpp_split.suggest_splits(600_000_000_000, channels_with_funds, exclude_single_part_payments=True) uses_full_amount = False for c, a in splits[0].config.items(): if a == channels_with_funds[c]: uses_full_amount |= True self.assertFalse(uses_full_amount) def test_payment_below_min_part_size(self): amount = mpp_split.MIN_PART_SIZE_MSAT // 2 splits = mpp_split.suggest_splits(amount, self.channels_with_funds, exclude_single_part_payments=False) # we only get four configurations that end up spending the full amount # in a single channel self.assertEqual(4, len(splits)) def test_suggest_part_penalty(self): """Test is mainly for documentation purposes. Decreasing the part penalty from 1.0 towards 0.0 leads to an increase in the number of parts a payment is split. A configuration which has about equally distributed amounts will result.""" with self.subTest(msg="split payments with intermediate part penalty"): mpp_split.PART_PENALTY = 1.0 splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds) self.assertEqual(2, splits[0].config.number_parts()) with self.subTest(msg="split payments with intermediate part penalty"): mpp_split.PART_PENALTY = 0.3 splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds) self.assertEqual(4, splits[0].config.number_parts()) with self.subTest(msg="split payments with no part penalty"): mpp_split.PART_PENALTY = 0.0 splits = mpp_split.suggest_splits(1_100_000_000, self.channels_with_funds) self.assertEqual(5, splits[0].config.number_parts()) def test_suggest_splits_single_channel(self): channels_with_funds = { (b"0", b"0"): (1_000_000_000, 3), } with self.subTest(msg="do a payment with the maximal amount spendable on a single channel"): splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_part_payments=False) self.assertEqual(1, len(splits[0].config[(b"0", b"0")])) self.assertEqual({(b"0", b"0"): [1_000_000_000]}, splits[0].config) with self.subTest(msg="test sending an amount greater than what we have available"): self.assertRaises(NoPathFound, mpp_split.suggest_splits, *(1_100_000_000, channels_with_funds)) with self.subTest(msg="test sending a large amount over a single channel in chunks"): mpp_split.PART_PENALTY = 0.5 splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_part_payments=False) self.assertEqual(2, len(splits[0].config[(b"0", b"0")])) with self.subTest(msg="test sending a large amount over a single channel in chunks"): mpp_split.PART_PENALTY = 0.3 splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_part_payments=False) self.assertEqual(3, len(splits[0].config[(b"0", b"0")])) with self.subTest(msg="exclude all single channel splits"): mpp_split.PART_PENALTY = 0.3 splits = mpp_split.suggest_splits(1_000_000_000, channels_with_funds, exclude_single_channel_splits=True) self.assertEqual(1, len(splits[0].config[(b"0", b"0")]))