Add interop integration test harness for LND, CLN, and Eclair by febyeji · Pull Request #839 · lightningdevkit/ldk-node

febyeji · 2026-03-24T15:43:01Z

Summary

Closes #766

Add a interop test harness for testing LDK-Node against external Lightning implementations (LND, CLN, Eclair).

What changed

ExternalNode trait (tests/common/external_node.rs): common interface for all external Lightning implementations (get_node_id, open_channel, create_invoice, close_channel, force_close, send_to_route, etc.)
Reusable scenario functions (tests/common/scenarios/): channel lifecycle, payments (bolt11, keysend, bidirectional, concurrent), disconnect/reconnect, expired invoice, fee-change close — plus a combo orchestrator that runs 16 disconnect×payment×close permutations
Refactored CLN/LND tests: replaced ~380 lines of duplicated inline logic with interop_tests!(setup_clients) macro that runs the full shared suite
New Eclair support: TestEclairNode impl, Dockerfile, docker-compose, CI workflow
Event macro timeouts: all expect_*_event! macros now timeout after 60s with a message identifying which event was expected, instead of hanging indefinitely

Implementation	Image	Version
CLN	`elementsproject/lightningd`	v25.12.1
LND	`lightninglabs/lnd`	v0.20.1-beta
Eclair	`acinq/eclair`	latest (0.14.0-SNAPSHOT)

Known issues

test_cln_splice_in is #[ignore]: rust-lightning panics during tx_signatures exchange (channel.rs debug_assert), fix merged in rust-lightning#4472 but not yet in the pinned rev (see Assertion on !is_monitor_update_in_progress() is hit during splicing attempt on VSS #857)
test_cln_receive_keysend is #[ignore]: CLN keysend sets final_cltv=22 which is below LDK's minimum of 42

ldk-reviews-bot · 2026-03-24T15:43:03Z

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ldk-reviews-bot · 2026-03-26T15:55:25Z

🔔 1st Reminder

Hey @tnull! This PR has been waiting for your review.
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tnull

Thanks, this already looks great on the first pass! I think we should get some minor things out of the way and then move forward with this so we can take advantage of the additional test coverage for our upcoming release already.

Some comments def. can be addressed in a follow-up (e.g. adding BOLT12 test coverage would be great).

tests/docker/docker-compose-cln.yml

.github/workflows/cln-integration.yml

.github/workflows/lnd-integration.yml

Cargo.toml

.github/workflows/eclair-integration.yml

tests/common/mod.rs

tests/integration_tests_cln.rs

tests/integration_tests_eclair.rs

tests/common/scenarios/mod.rs

…setup Address review feedback on PR lightningdevkit#839: - Replace reqwest dependency with bitreq for Eclair REST client - Replace curl shell calls with bitreq async HTTP requests - Remove per-test docker container recreation (reuse single Eclair instance, unlock UTXOs between tests instead) - Fix chmod -R 755 to u+rwX,go+rX in CLN/LND CI workflows - Add --fail flag to curl readiness check in Eclair CI

febyeji · 2026-03-28T16:43:09Z

Thanks for the review! Pushed an update addressing the feedback. Will address in follow-ups:

Move docker files to tests/docker/
Add BOLT12 scenario coverage

tnull · 2026-03-30T08:40:42Z

Thanks for the review! Pushed an update addressing the feedback. Will address in follow-ups:

Move docker files to tests/docker/

Add BOLT12 scenario coverage

Thanks! Mind opening tracking issues for these so we don't forget?

tnull

CI is failing right now:

thread 'test_eclair_cooperative_close_after_fee_change' (16127) panicked at tests/common/scenarios/channel.rs:275:55:
called `Result::unwrap()` on an `Err` value: ChannelClosingFailed
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    test_eclair_cooperative_close_after_fee_change

febyeji · 2026-03-30T10:13:47Z

@tnull Fixed the test_eclair_cooperative_close_after_fee_change CI failure! The remaining channel_full_cycle_with_vss_store failure is from VSS tests, and I believe a rerun could clear it. Also I opened the tracking issues for the follow-ups.

tnull

Thanks for addressing the feedback! Here are some more comments.

What stands out to me is that:

This PR/the code is very verbose. It would be good to simplify and DRY up where possible to improve maintainability going forward.
We currently ignore a lot of test cases, often for reasons that aren't conclusive to me (or seem outdated). Can we double-check whether we really can't make them work?

.github/workflows/cln-integration.yml

.github/workflows/rust.yml

tests/common/scenarios/channel.rs

tests/common/lnd.rs

tests/common/cln.rs

.github/workflows/rust.yml

tests/integration_tests_cln.rs

tnull · 2026-04-02T12:23:48Z

tests/integration_tests_cln.rs

+}
+
+/// CLN v24.08+ includes a `payment_secret` in outbound keysend HTLCs.
+/// LDK treats any inbound HTLC with `payment_secret` as a BOLT11 payment and


Hmm, I'm not positive this is true? Could you un-ignore this so we can see what the error actually is? Is it related to the checks here?: https://github.com/lightningdevkit/rust-lightning/blob/db42ad6ba053d54f98f360f05afad5fee896ed69/lightning/src/ln/channelmanager.rs#L8479

This is the keysend test, not force close. CLN's keysend plugin hardcodes min_final_cltv_expiry=22 (plugins/keysend.c:230), but LDK requires at least 42 (HTLC_FAIL_BACK_BUFFER(39) + 3). CLN's keysend RPC has no parameter to override this. Keeping ignored until CLN adds a final_cltv parameter.

This is the keysend test, not force close.

I'm confused what you mean by that?

CLN's keysend plugin hardcodes min_final_cltv_expiry=22 (plugins/keysend.c:230), but LDK requires at least 42 (HTLC_FAIL_BACK_BUFFER(39) + 3). CLN's keysend RPC has no parameter to override this. Keeping ignored until CLN adds a final_cltv parameter.

Okay, interesting, but that seems an entirely different issue than originally described in the comment / PR description? Or am I confused? The comment now says "needs CLN upstream fix", but are they even aware of the issue and agreed it should be fixed?

This is the keysend test, not force close.

Sorry for the confusing wording, I think I misread your original comment as asking about a different test.
You're right that there's no upstream CLN issue filed for this.

The min_final_cltv_expiry=22 hardcoding in plugins/keysend.c is something I found by reading CLN source, but I haven't confirmed whether the CLN team considers it a bug. will un-ignored the test so we can see the actual error in CI.

Now opened ElementsProject/lightning#9034

tests/integration_tests_eclair.rs

…setup Address review feedback on PR lightningdevkit#839: - Replace reqwest dependency with bitreq for Eclair REST client - Replace curl shell calls with bitreq async HTTP requests - Remove per-test docker container recreation (reuse single Eclair instance, unlock UTXOs between tests instead) - Fix chmod -R 755 to u+rwX,go+rX in CLN/LND CI workflows - Add --fail flag to curl readiness check in Eclair CI

Update test infrastructure to Bitcoin Core 29.0: - corepc-node feature: 27_2 → 29_0 - electrsd feature: corepc-node_27_2 → corepc-node_29_0 - download script: bitcoind 27.2 → 29.0 with updated SHA256 hashes Prerequisite for lightningdevkit#839 (interop test harness) which needs bitcoind 29.0 for compatibility with updated Docker images.

Update test infrastructure to Bitcoin Core 29.0: - corepc-node: 0.10.0 → 0.10.1, feature 27_2 → 29_0 - electrsd feature: corepc-node_27_2 → corepc-node_29_0 - download script: bitcoind 27.2 → 29.0 with updated SHA256 hashes Prerequisite for lightningdevkit#839 (interop test harness).

…setup Address review feedback on PR lightningdevkit#839: - Replace reqwest dependency with bitreq for Eclair REST client - Replace curl shell calls with bitreq async HTTP requests - Remove per-test docker container recreation (reuse single Eclair instance, unlock UTXOs between tests instead) - Fix chmod -R 755 to u+rwX,go+rX in CLN/LND CI workflows - Add --fail flag to curl readiness check in Eclair CI

febyeji · 2026-04-06T08:08:57Z

Pushed an update addressing all review feedback. I've replied with details on each change. While I was writing comments, GitHub seems to have posted some duplicate ones. I've since deleted them, so please ignore any notifications from those.

Bump test dependencies, reorganize Docker files, and add interop integration test infrastructure with shared scenario runner for CLN, LND, and Eclair.

tnull self-requested a review March 24, 2026 15:55

febyeji force-pushed the interop-test-harness branch 4 times, most recently from 8c1e94f to a50c9d0 Compare March 26, 2026 15:49

febyeji force-pushed the interop-test-harness branch from a50c9d0 to 433515c Compare March 26, 2026 17:36

febyeji marked this pull request as ready for review March 26, 2026 17:54

tnull reviewed Mar 27, 2026

View reviewed changes

febyeji force-pushed the interop-test-harness branch from 433515c to 2613a3f Compare March 28, 2026 16:00

febyeji force-pushed the interop-test-harness branch from 2613a3f to 9c2fbdc Compare March 28, 2026 16:06

febyeji force-pushed the interop-test-harness branch from 9c2fbdc to 7420893 Compare March 28, 2026 16:21

tnull reviewed Mar 30, 2026

View reviewed changes

This was referenced Mar 30, 2026

Move interop test Docker files to tests/docker/ #855

Closed

Add BOLT12 scenario coverage to interop test harness #856

Open

tnull reviewed Apr 2, 2026

View reviewed changes

febyeji mentioned this pull request Apr 3, 2026

Bump test dependencies and reorganize Docker files #869

Merged

febyeji force-pushed the interop-test-harness branch 2 times, most recently from f039418 to 96517d1 Compare April 6, 2026 08:08

febyeji force-pushed the interop-test-harness branch 2 times, most recently from 1bc1de3 to 54fc858 Compare April 7, 2026 07:04

feat(test): add interop test harness for CLN, LND, Eclair

10d4cd8

Bump test dependencies, reorganize Docker files, and add interop integration test infrastructure with shared scenario runner for CLN, LND, and Eclair.

febyeji force-pushed the interop-test-harness branch from 54fc858 to 10d4cd8 Compare April 7, 2026 07:22

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