lnwallet: fix HTLC trimming test case to use dust_limit for zero-fee HTLCs
What the developer wrote
Authored by Olaoluwa Osuntokun
lnwallet: fix HTLC trimming test case to use dust_limit for zero-fee HTLCs
In this commit, we fix the "commitment tx with some HTLCs trimmed" test
case to actually exercise trimming for taproot's zero-fee HTLC
transactions.
With zero-fee second-level HTLCs, the HTLC output value on the
commitment transaction equals the HTLC amount directly (no fee is
deducted). This means trimming is determined solely by whether the HTLC
amount falls below the dust limit, not by the fee rate. The previous
parameters (fee_per_kw=100000, dust_limit=546) didn't actually trim any
of the test HTLCs because even the smallest test HTLC (1000 sats) was
above the 546 sat dust limit.
We now use fee_per_kw=644 (a reasonable rate) and dust_limit=2500 to
ensure that the three smallest test HTLCs (1000, 2000, 2000 sats) are
properly trimmed, leaving only the 3000 and 4000 sat HTLCs on the
commitment transaction.
What changed, and why it matters
This commit only adjusts the numbers used inside a single test case so that the test actually exercises the intended behavior. It does not change any production code, protocol rules, or wallet logic. There is no security issue here.
No action needed; this is a benign test-only correction.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The change modifies test parameters in lnwallet/taproot_test_vectors_test.go for the ‘commitment tx with some HTLCs trimmed’ case. With taproot’s zero-fee second-level HTLCs, trimming depends only on whether the HTLC amount is below the dust limit. The old parameters (fee_per_kw=100000, dust_limit=546) left all test HTLCs above the dust limit, so no trimming occurred. The new parameters (fee_per_kw=644, dust_limit=2500) cause the 1000, 2000, and 2000 sat HTLCs to be trimmed while keeping the 3000 and 4000 sat HTLCs. This is purely a test-fix with no runtime effect.
Changed components
lnwallet/taproot_test_vectors_test.goInspect captured patch +2 / −2
diff --git a/lnwallet/taproot_test_vectors_test.go b/lnwallet/taproot_test_vectors_test.go
index 84a91ce..791c36f 100644
--- a/lnwallet/taproot_test_vectors_test.go
+++ b/lnwallet/taproot_test_vectors_test.go
@@ -894,8 +894,8 @@ var taprootTransactionTestCases = []struct {
name: "commitment tx with some HTLCs trimmed",
localBalance: 6_988_000_000,
remoteBalance: 3_000_000_000,
- feePerKw: 100_000,
- dustLimit: 546,
+ feePerKw: 644,
+ dustLimit: 2500,
useTestHtlcs: true,
},
}
Why this scored 15/100
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