test(bdd): add C++ SDK BDD tests for basic messaging by seokjin0414 · Pull Request #3554 · apache/iggy

seokjin0414 · 2026-06-23T09:50:27Z

What

Adds BDD coverage for the C++ SDK by implementing the shared
bdd/scenarios/basic_messaging.feature with cucumber-cpp and wiring it into the
Docker-based BDD harness and CI, the same way the other SDKs run. This is the
second part of #2965; the messaging FFI it relies on landed in #3046.

How it works

cucumber-cpp only supports the Cucumber wire protocol, so the step definitions
(bdd/cpp/features/step_definitions) build with CMake into a wire server, and a
Ruby Cucumber runner (cucumber + cucumber-wire, pinned to the versions
cucumber-cpp itself tests against) drives the feature file over the wire against a
real iggy-server. The step logic and assertions are all C++ and exercise the
SDK's FFI (get_streams, create_stream, create_topic, send_messages,
poll_messages). The Iggy C++ SDK is built with cargo and linked into the wire
server as a staticlib.

Heads-up for reviewers

Because cucumber-cpp is wire-protocol-only, the C++ BDD image pulls in a Ruby
runtime (cucumber + cucumber-wire). Flagging this explicitly in case it
changes how you'd like the harness shaped.

Notes

Everything lives under bdd/cpp, next to the other SDK BDD suites; foreign/cpp
is unchanged apart from the reserve() fix to the existing test.

The TearDown fixture and the magic-number cleanup discussed on Discord are tracked
separately by @slbotbm.

Refs #2965

slbotbm · 2026-06-23T10:14:01Z

@seokjin0414 the test should be in he root bdd/ folder, not inside of foreign/cpp

slbotbm · 2026-06-23T10:51:26Z

ignore the above, i didn't read the description😅

The oversized-payload test grew its 64 MB buffer one byte at a time and a comment claimed cxx::Vec had no public reserve API. It does, so reserve the capacity once before filling it. Signed-off-by: seokjin0414 <sars21@hanmail.net>

codecov · 2026-06-23T11:48:47Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.39%. Comparing base (74d62eb) to head (533c9b0).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3554      +/-   ##
============================================
- Coverage     74.41%   74.39%   -0.03%     
  Complexity      937      937              
============================================
  Files          1243     1243              
  Lines        125987   125987              
  Branches     101854   101901      +47     
============================================
- Hits          93756    93726      -30     
+ Misses        29218    29201      -17     
- Partials       3013     3060      +47

Components	Coverage Δ
Rust Core	`75.17% <ø> (-0.01%)`	⬇️
Java SDK	`62.44% <ø> (ø)`
C# SDK	`71.40% <ø> (-0.71%)`	⬇️
Python SDK	`88.88% <ø> (ø)`
PHP SDK	`84.29% <ø> (ø)`
Node SDK	`91.35% <ø> (+0.22%)`	⬆️
Go SDK	`40.14% <ø> (ø)`
see 32 files with indirect coverage changes

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seokjin0414 · 2026-06-23T23:29:30Z

@slbotbm
no worries! ended up moving it to bdd/cpp anyway. i kept it out of foreign/cpp by building the wire server with CMake (FetchContent cucumber-cpp + the cxx staticlib) instead of Bazel, so it's self-contained like the other bdd dirs and
foreign/cpp now only carries the reserve() fix.
can switch it to a Bazel target under foreign/cpp if you'd prefer.

slbotbm · 2026-06-24T04:56:04Z

@seokjin0414 I didn't understand why did you use cmake instead of bazel. I think it would be possible to use bazel in bdd/cpp. you could define iggy_cpp as a bazel dependency in bdd/cpp/MODULE.bazel, and then locally define the path to iggy_cpp as ../../foreign/cpp.

slbotbm · 2026-06-24T17:56:55Z

/author

The C++ SDK had no BDD coverage. Add cucumber-cpp step definitions under bdd/cpp that drive the shared basic_messaging.feature through the C++ FFI client. cucumber-cpp uses the wire protocol, so bdd/cpp is a self-contained Bazel module: it builds the step definitions into a wire server (pulling cucumber-cpp from the Bazel registry and the Iggy C++ SDK from foreign/cpp via local_path_override) that a Ruby Cucumber runner connects to. The SDK's iggy-cpp target is made public so the harness can depend on it. A per-file CUKE_OBJECT_PREFIX keeps the generated step classes from clashing across translation units. The Gemfile and cucumber.wire comment styles are registered with the license checker. Signed-off-by: seokjin0414 <sars21@hanmail.net>

A Ruby cucumber runner with cucumber-wire drives the wire server over the wire protocol against a real iggy-server. Register the cpp-bdd compose service, the run-bdd-tests entry, and the bdd-cpp CI component so it runs like the other SDK BDD suites. Signed-off-by: seokjin0414 <sars21@hanmail.net>

seokjin0414 · 2026-06-24T23:52:58Z

@slbotbm the cmake route was just to keep the test self-contained in bdd/cpp without touching foreign/cpp — i didn't realize local_path_override could pull the sdk in cleanly. it can, so i switched to bazel as you suggested: bdd/cpp is its own module now, cucumber-cpp from the registry + iggy_cpp via local_path_override(../../foreign/cpp). cmake is gone.

the only change to foreign/cpp is one line — making the iggy-cpp target public so the harness can depend on it. build + the full wire e2e (17 steps) pass.

slbotbm

Let's add a .clang-format as well that copies the one from foreign/cpp

You can use /ready when your PR is ready for review again

slbotbm · 2026-06-26T05:02:53Z

+cc_binary(
+    name = "bdd_wire_server",
+    srcs = glob([
+        "features/step_definitions/*.cpp",
+        "features/step_definitions/*.hpp",
+    ]),
+    copts = select({
+        "@platforms//os:windows": ["/utf-8"],
+        "//conditions:default": [
+            "-finput-charset=UTF-8",
+            "-fexec-charset=UTF-8",
+        ],
+    }),
+    includes = [
+        "features/step_definitions",
+    ],
+    testonly = True,
+    deps = [
+        "@cucumber-cpp//:cucumber-cpp",
+        "@googletest//:gtest",
+        "@iggy_cpp//:iggy-cpp",
+    ],
+)


Let's add the following flags: -Wall, -Wpedantic, -Werror, -Wextra, -g3, -O0, -fno-omit-frame-pointer, -DDEBUG

Also linkopts = ["-g"]

slbotbm · 2026-06-26T05:24:28Z

+RUN printf '%s\n' \
+    '#!/bin/bash' \
+    'set -euo pipefail' \
+    'if [ -d /app/features ]; then' \
+    '  cp -f /app/features/*.feature /workspace/bdd/cpp/features/ 2>/dev/null || true' \
+    'fi' \
+    'bdd_wire_server &' \
+    'server_pid=$!' \
+    'sleep 2' \
+    'cd /workspace/bdd/cpp' \
+    'set +e' \
+    'bundle exec cucumber' \
+    'status=$?' \
+    'kill "$server_pid" 2>/dev/null || true' \
+    'exit $status' \
+    > /entrypoint.sh \
+    && chmod +x /entrypoint.sh


Let's add a real scripts/entrypoint.sh instead of creating it on the fly.

slbotbm · 2026-06-26T05:25:23Z

+    visibility = ["//visibility:public"],
 )


Let's add a version to iggy_cpp (0.1.0)

slbotbm · 2026-06-26T05:30:23Z

+# cucumber-cpp and its transitive deps (asio, tclap, ...) are not clean under strict warnings.
+# Silence warnings for external sources so they never fail the wire-server build.
+build --per_file_copt=external/.*@-w


By adding the flags to BUILD.bazel, this is not required anymore.

slbotbm · 2026-06-26T05:30:40Z

+# This harness resolves its module graph fresh in the build environment (Docker), so it does
+# not commit a MODULE.bazel.lock.
+common --lockfile_mode=off


Please remove this and commit the lockfile

slbotbm · 2026-06-26T05:31:25Z

+bazel_dep(name = "rules_cc", version = "0.2.18")
+bazel_dep(name = "platforms", version = "1.1.0")
+bazel_dep(name = "googletest", version = "1.17.0.bcr.2")
+bazel_dep(name = "cucumber-cpp", version = "0.8.0.bcr.1")


Is platforms required?

slbotbm · 2026-06-26T05:40:32Z

Let's also commit the ruby lockfile as well.

seokjin0414 marked this pull request as ready for review June 23, 2026 09:57

github-actions Bot added the S-waiting-on-review PR is waiting on a reviewer label Jun 23, 2026

seokjin0414 force-pushed the 2965-cpp-bdd-tests branch from 9d6f66a to d670d13 Compare June 23, 2026 10:26

test(cpp): reserve oversized payload buffer up front

abd3d4c

The oversized-payload test grew its 64 MB buffer one byte at a time and a comment claimed cxx::Vec had no public reserve API. It does, so reserve the capacity once before filling it. Signed-off-by: seokjin0414 <sars21@hanmail.net>

seokjin0414 force-pushed the 2965-cpp-bdd-tests branch from d670d13 to dfc8f20 Compare June 23, 2026 10:56

seokjin0414 force-pushed the 2965-cpp-bdd-tests branch from dfc8f20 to 0e70305 Compare June 23, 2026 22:56

github-actions Bot added S-waiting-on-author PR is waiting on author response and removed S-waiting-on-review PR is waiting on a reviewer labels Jun 24, 2026

seokjin0414 added 2 commits June 25, 2026 08:40

seokjin0414 force-pushed the 2965-cpp-bdd-tests branch from 0e70305 to 533c9b0 Compare June 24, 2026 23:41

slbotbm suggested changes Jun 26, 2026

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What

How it works

Heads-up for reviewers

Notes

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