What the developer wrote
Authored by f321x
regtest: make extract_preimage less flaky
Wait until the lnpay screen commands in the `extract_preimage`
regtest return before checking their log output to prevent a race
where the preimage becomes available but the log doesn't yet contain
the success string.
```
***** test_extract_preimage ******
initializing alice
funding alice
a6f8f660a3bab3c4af636849dae55f4c7d5d483289a5812c7efce19f4c701753
initializing bob
funding bob
b51eae095f875c7a796e74d87d6e4c21d42348272159ee30bd81ce7d9f18defe
mining 1 blocks
starting daemon (PID 5040)
/tmp/alice/regtest/wallets/default_wallet
true
starting daemon (PID 5060)
/tmp/bob/regtest/wallets/default_wallet
true
alice opens channel
7cde6dcba2a0d033ecd40c1c7cb8eec4c554acb1a09099eb1206ba39a93728ae:1
mining 3 blocks
wait until alice sees channel open.
wait until alice sees channel open..
wait until alice sees channel open...
0caecfe64e319771d60f6f1e488f28d64667783432a15fccab534dfffb2096a4
mining 1 blocks
wait until alice has preimage for c217931809c870a8032d536e59ccf2399a5d96b937818c64ae60c7e7d5363728.
wait until alice has preimage for c217931809c870a8032d536e59ccf2399a5d96b937818c64ae60c7e7d5363728..
wait until alice has preimage for c217931809c870a8032d536e59ccf2399a5d96b937818c64ae60c7e7d5363728...
wait until bob has preimage for c53556db6fcffcb2dd7c6b215e94d1af9c96e42c7170ae11e47b03a929917f28.
bob payment failed
Daemon stopped
Daemon stopped
......F
======================================================================
FAIL: test_extract_preimage (tests.regtest.TestLightningAB)
```
What changed, and why it matters
This commit fixes a flaky automated test, not a security bug in the Electrum wallet. It adds a wait step so the test script doesn't check log files before background payment commands have finished writing to them. There is no change to production code or user-facing behavior.
No security action needed. Treat as a normal test reliability improvement.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The patch modifies tests/regtest/regtest.sh in the extract_preimage regression test. It inserts a loop that waits until no GNU screen sessions whose names end in _payment are still running before reading /tmp/alice/screen1.log and /tmp/bob/screen1.log to verify payment success. This prevents a race condition where the preimage is already available but the lnpay command’s success output has not yet been flushed to the log, causing intermittent test failures. No wallet, daemon, Lightning protocol, or cryptographic code is changed.
Changed components
tests/regtest/regtest.shInspect captured patch +1 / −0
diff --git a/tests/regtest/regtest.sh b/tests/regtest/regtest.sh
index 47ee7e4..ced9f0b 100755
--- a/tests/regtest/regtest.sh
+++ b/tests/regtest/regtest.sh
@@ -566,6 +566,7 @@ if [[ $1 == "extract_preimage" ]]; then
new_blocks 1
wait_until_preimage alice $rhash1
wait_until_preimage bob $rhash2
+ while screen -ls | grep -q _payment; do sleep 1; done # wait until lnpay return before checking logs
# check both "lnpay" commands succeeded
success=$(cat /tmp/alice/screen1.log | jq -r ".success")
if [[ "$success" != "true" ]]; then echo "alice payment failed"; exit 1; fi
Why this scored 15/100
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