Feature: Implement js-libp2p Interop Tests for Echo Protocol

[Keerthivasan-Venkitajalam]

Description

Add a new interoperability test suite that validates py-libp2p against js-libp2p using the Echo protocol (/echo/1.0.0).

Motivation

As part of the Universal Connectivity initiative (2026 Roadmap), py-libp2p is expanding its interoperability coverage to ensure parity with other stack implementations.

Currently, the repository has:

• nim-libp2p: Echo protocol tests.
• go-libp2p & rust-libp2p: Active work on Ping/Echo (Issues Implement go-libp2p interop tests (echo protocol) #1136, Implement the rust-libp2p interop test #1142).

However, we are missing a dedicated Echo Protocol test for js-libp2p. Validating the Echo protocol is critical because it tests full bidirectional stream read/write capabilities (muxing, window management, payload integrity), whereas simple Ping tests often miss subtle stream handling bugs (e.g., Yamux hangs).

Requirements

1. JS Echo Server:

• Create a new script at tests/interop/js_libp2p/js_node/src/echo_server.js.
• This script should spin up a js-libp2p node listening on TCP that handles /echo/1.0.0 by piping the stream back to the source.

2. Python Test Harness:

• Create a new test file at tests/interop/js_libp2p/test_js_echo.py.
• Implement a pytest fixture to manage the JS daemon lifecycle (similar to the existing Nim implementation).
• Implement the test function using trio to dial the JS peer and verify payload integrity.

Open questions

None.

Are you planning to do it yourself in a pull request ?

Yes

[seetadev]

@Keerthivasan-Venkitajalam : Thanks a lot for picking this up and for the detailed issue write-up. This is a great direction, and the motivation around Echo vs Ping is spot on 👍

Echo is exactly the kind of test that flushes out real stream/muxing edge cases, so this aligns very well with the Universal Connectivity goals.

A few quick clarifications to help you land this cleanly:

• Interop tests PR location
  Interoperability test suites should live in https://github.com/libp2p/test-plans, not directly in the py-libp2p repo.
  Please refer to the structure and conventions documented here:
  https://github.com/libp2p/test-plans/tree/master/docs
  That repo is the canonical place where cross-implementation test plans and harnesses are reviewed and evolved together.

• py-libp2p repository scope
  PRs to py-libp2p → main should only be opened when:

  • You are modifying core library behavior, or
  • You are adding/updating shared utilities used by the library itself
    Test plans and cross-stack validation logic should stay out of the core repo and instead live under test-plans.

• JS Echo server + Python harness
  The approach you outlined (JS echo server + Python pytest/trio harness) makes sense conceptually 👍
  The main adjustment is where that code lands:

  • JS node scripts and orchestration logic → test-plans
  • py-libp2p should only be touched if you discover missing primitives or bugs while implementing the test

• Maintainers sync
  Since you’re a new contributor, I’d strongly recommend joining the libp2p maintainers meeting every Thursday.
  It’s the fastest way to:

  • Sanity-check interop test scope
  • Align with parallel work in go / rust / js
  • Avoid duplicated effort (especially around Echo vs Ping coverage)

Overall: this is solid, thoughtful work, and very much in line with where libp2p is headed in 2026.

If you move this into test-plans and follow the documented structure, I’m happy to review and help iterate. Keep going 🚀

CCing @sumanjeet0012 , @acul71 , @dhuseby

[Keerthivasan-Venkitajalam]

@Keerthivasan-Venkitajalam : Thanks a lot for picking this up and for the detailed issue write-up. This is a great direction, and the motivation around Echo vs Ping is spot on 👍

Echo is exactly the kind of test that flushes out real stream/muxing edge cases, so this aligns very well with the Universal Connectivity goals.

A few quick clarifications to help you land this cleanly:

• Interop tests PR location
  Interoperability test suites should live in https://github.com/libp2p/test-plans, not directly in the py-libp2p repo.
  Please refer to the structure and conventions documented here:
  https://github.com/libp2p/test-plans/tree/master/docs
  That repo is the canonical place where cross-implementation test plans and harnesses are reviewed and evolved together.

• py-libp2p repository scope
  PRs to py-libp2p → main should only be opened when:

  • You are modifying core library behavior, or
  • You are adding/updating shared utilities used by the library itself
    Test plans and cross-stack validation logic should stay out of the core repo and instead live under test-plans.

• JS Echo server + Python harness
  The approach you outlined (JS echo server + Python pytest/trio harness) makes sense conceptually 👍
  The main adjustment is where that code lands:

  • JS node scripts and orchestration logic → test-plans
  • py-libp2p should only be touched if you discover missing primitives or bugs while implementing the test

• Maintainers sync
  Since you’re a new contributor, I’d strongly recommend joining the libp2p maintainers meeting every Thursday.
  It’s the fastest way to:

  • Sanity-check interop test scope
  • Align with parallel work in go / rust / js
  • Avoid duplicated effort (especially around Echo vs Ping coverage)

Overall: this is solid, thoughtful work, and very much in line with where libp2p is headed in 2026.

If you move this into test-plans and follow the documented structure, I’m happy to review and help iterate. Keep going 🚀

CCing @sumanjeet0012 , @acul71 , @dhuseby

@seetadev Thank you very much for the detailed clarification — really appreciate the guidance 🙂

Understood that new interoperability test suites should live in libp2p/test-plans, and that py-libp2p should only be touched if core library changes or shared utilities are required. I’ll adjust my plan accordingly and move the JS Echo server + Python harness implementation into the test-plans repository following the documented structure.

Next steps on my side:

• Set up the js-libp2p Echo server script under test-plans
• Implement the Python trio-based interop harness following existing conventions
• Open an early draft PR in libp2p/test-plans, referencing this issue (Feature: Implement js-libp2p Interop Tests for Echo Protocol #1155) for context

If I encounter missing primitives or bugs in py-libp2p during implementation, I’ll open focused PRs there separately.

I’ll also try to join the maintainers call this Thursday to sync on scope and avoid duplicating parallel Echo/Ping efforts.

excited to contribute to the Universal Connectivity push.