itest: fix flake in testIntroductionNodeError
What the developer wrote
Authored by ziggie
itest: fix flake in testIntroductionNodeError
`testRelayingBlindedError` already uses `flakePaymentStreamReturnEarly`
after draining Carol's outgoing liquidity for the same reason:
`drainCarolLiquidity` causes the draining node to originate a payment,
which produces SEND-type HTLC notifier events. Because `SendPaymentV2`
returns SUCCEEDED before the commitment dance (revoke-and-ack exchange)
completes, those events can still be in-flight when the test subscribes
to HTLC events. The htlc notifier's subscribe server races a pending
SendUpdate against the Subscribe call in a single handler goroutine; if
registration wins the random select, the stale SEND events land on the
new subscriber and corrupt the subsequent FORWARD-type assertion.
`testIntroductionNodeError` has the same pattern — Bob drains Carol's
incoming liquidity by originating a payment — but was missing the sleep.
Add `flakePaymentStreamReturnEarly()` to match the existing workaround.
Fixes: https://github.com/lightningnetwork/lnd/actions/runs/24278289474/job/70895848920
What changed, and why it matters
This is a test-only change that adds a short sleep to an integration test to avoid a race condition between payment completion and event subscription. It does not change production code or affect real users' funds, channels, or node security.
No security action needed. This is a test reliability fix; review and merge as normal.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The commit adds flakePaymentStreamReturnEarly() in testIntroductionNodeError after draining Carol’s liquidity. The drain triggers a payment from Bob, which can leave SEND-type HTLC notifier events in-flight because SendPaymentV2 returns success before the revoke-and-ack commitment dance finishes. If the test subscribes to HTLC events before those stale events are flushed, they can be delivered to the new subscriber and corrupt a later FORWARD-type assertion. The same workaround already exists in testRelayingBlindedError. No production code is modified.
Changed components
itest/lnd_route_blinding_test.goInspect captured patch +7 / −0
diff --git a/itest/lnd_route_blinding_test.go b/itest/lnd_route_blinding_test.go
index 3ad1f45..2c69548 100644
--- a/itest/lnd_route_blinding_test.go
+++ b/itest/lnd_route_blinding_test.go
@@ -704,6 +704,13 @@ func testIntroductionNodeError(ht *lntest.HarnessTest) {
// at the introduction node.
testCase.drainCarolLiquidity(true)
+ // NOTE: The drain above causes Bob to originate a payment, producing
+ // SEND-type HTLC events that may still be in-flight when we subscribe.
+ // Wait for the commitment dance to finish so those events are flushed
+ // before we subscribe, preventing them from corrupting the assertion
+ // below.
+ flakePaymentStreamReturnEarly()
+
// Subscribe to Bob's HTLC events so that we can observe the payment
// coming in.
bobEvents := bob.RPC.SubscribeHtlcEvents()
Why this scored 15/100
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