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askrene: test explain: fix flake
Public commit record
98/100 · Strong
What the developer wrote
Authored by Lagrang3
askrene: test explain: fix flake
Fix test_explain_source_dest_failure by increasing the amounts by a
factor of ten, which reduces the relative significance of on-chain fees
on the commitment transaction.
This used to fail on liquid-regtest due to insufficient liquidity on
l2->l4 to prevent channel starvation.
At line
```
l1.rpc.xpay(l4.rpc.invoice('30000sat', 'test_explain_simple_failures2', 'test_explain_simple_failures2')['bolt11'])
```
we would get
```
lightningd-2 2026-07-06T11:29:09.973Z DEBUG 02287bfac8b99b35477ebe9334eede1e32b189e24644eb701c079614712331cec0-channeld-chan#3: Adding HTLC would leave us only 19454000msat: we need 25281sat for another HTLC if fees increase from 7500perkw to 13906perkw
lightningd-2 2026-07-06T11:29:09.973Z DEBUG 02287bfac8b99b35477ebe9334eede1e32b189e24644eb701c079614712331cec0-channeld-chan#3: Adding HTLC 0 amount=30000000msat cltv=130 gave CHANNEL_ERR_CHANNEL_CAPACITY_EXCEEDED
```
Changelog-None
Signed-off-by: Lagrang3 <lagrang3@protonmail.com>
✓ Descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context✓ Explains rationale or failure mode✓ Mentions testing or verification✓ Links an issue, advisory, or supporting reference
What changed, and why it matters
This commit only changes a test file. It makes the test channels and payment amounts ten times larger so that small on-chain fee variations no longer cause the test to fail on liquid-regtest. There is no change to production code, no user-facing behavior change, and no security fix.
Recommended action
No action required. This is a test-only flake fix with no security relevance.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The commit modifies tests/test_askrene.py in the askrene plugin test suite. It scales channel funding amounts and route-request amounts by 10x in test_explain_source_dest_failure to avoid a flaky failure caused by on-chain commitment-transaction fee uncertainty consuming a large relative portion of the small channel capacity on the l2->l4 channel. The production routing, xpay, or askrene logic is untouched.
Changed components
tests/test_askrene.pyInspect captured patch +13 / −13
diff --git a/tests/test_askrene.py b/tests/test_askrene.py
index daf93bd9..1032cf8b 100644
--- a/tests/test_askrene.py
+++ b/tests/test_askrene.py
@@ -2744,15 +2744,15 @@ def test_bad_user_entries(node_factory):
def test_explain_source_dest_failures(node_factory, bitcoind):
"""askrene should give intelligent failure reasons when source or destination don't have
capacity"""
- # l1 --100k--> l2 --200k--> l3
+ # l1 --1000k--> l2 --2000k--> l3
# |
- # 50k
+ # 500k
# v
# l4
l1, l2, l3, l4 = node_factory.get_nodes(4)
- node_factory.join_nodes([l1, l2], fundamount=100000)
- node_factory.join_nodes([l2, l3], fundamount=200000)
- node_factory.join_nodes([l2, l4], fundamount=50000)
+ node_factory.join_nodes([l1, l2], fundamount=1000000)
+ node_factory.join_nodes([l2, l3], fundamount=2000000)
+ node_factory.join_nodes([l2, l4], fundamount=500000)
# Make sure everyone knows everything
bitcoind.generate_block(5)
@@ -2760,45 +2760,45 @@ def test_explain_source_dest_failures(node_factory, bitcoind):
# We can't afford this
with pytest.raises(RpcError,
- match=r"We could not find a usable set of paths. Total source capacity is only 100000000msat \(in 1 channels\)"):
+ match=r"We could not find a usable set of paths. Total source capacity is only 1000000000msat \(in 1 channels\)"):
l1.rpc.getroutes(source=l1.info['id'],
destination=l3.info['id'],
- amount_msat='100001sat',
+ amount_msat='1000001sat',
layers=['auto.localchans', 'auto.sourcefree'],
maxfee_msat=10000,
final_cltv=5)
# They can't afford this
with pytest.raises(RpcError,
- match=r"We could not find a usable set of paths. Total destination capacity is only 50000000msat \(in 1 channels\)"):
+ match=r"We could not find a usable set of paths. Total destination capacity is only 500000000msat \(in 1 channels\)"):
l1.rpc.getroutes(source=l1.info['id'],
destination=l4.info['id'],
- amount_msat='50001sat',
+ amount_msat='500001sat',
layers=['auto.localchans', 'auto.sourcefree'],
maxfee_msat=10000,
final_cltv=5)
# Add some information, and we should know that too.
- l1.rpc.xpay(l4.rpc.invoice('30000sat', 'test_explain_simple_failures2', 'test_explain_simple_failures2')['bolt11'])
+ l1.rpc.xpay(l4.rpc.invoice('300000sat', 'test_explain_simple_failures2', 'test_explain_simple_failures2')['bolt11'])
# This is actually just auto.localchans knowing the capacity!
with pytest.raises(RpcError,
match=r"We could not find a usable set of paths. We know from auto.localchans that source has maximum capacity [0-9]*msat \(in 1 channels\)") as err:
l1.rpc.getroutes(source=l1.info['id'],
destination=l3.info['id'],
- amount_msat='80001sat',
+ amount_msat='700001sat',
layers=['auto.localchans', 'auto.sourcefree', 'xpay'],
maxfee_msat=10000,
final_cltv=5)
PAY_INSUFFICIENT_FUNDS = 215
assert err.value.error['code'] == PAY_INSUFFICIENT_FUNDS
- # This is the impression in the xpay layer telling us 30,000sat is already gone (of 50,000).
+ # This is the impression in the xpay layer telling us 300,000sat is already gone (of 500,000).
with pytest.raises(RpcError,
match=r"We could not find a usable set of paths. We know from xpay that destination has maximum capacity [0-9]*msat \(in 1 channels\)") as err:
l1.rpc.getroutes(source=l1.info['id'],
destination=l4.info['id'],
- amount_msat='20001sat',
+ amount_msat='200001sat',
layers=['auto.localchans', 'auto.sourcefree', 'xpay'],
maxfee_msat=10000,
final_cltv=5)
Risk score
Our methodology →Why this scored 15/100
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