fix(ros): make the interop gate count interop tests

[YuanYuYuan]

Summary

The interop gate added in #271 does not count interop tests. It asserts a non-zero package total, then reports that total as interop:

Summary [47.809s] 125 tests run: 125 passed, 3 skipped
125 ROS interop tests ran against rmw_zenoh_cpp.

Only 41 of those are interop tests. Counting test functions in crates/hiroz-tests/tests/:

suite	tests
pubsub_interop	14
demo_nodes	9
service_interop	7
type_description_interop	4 (absent on Humble)
action_interop	4
parameter_interop	3

The rest of the package is lifecycle, cache, hu_meter, parameter_tests and friends. Delete every interop test and the gate still prints a confident number. That is the defect #271 was written to remove, reintroduced in the fix.

What this PR does

One file changes: scripts/test-ros.nu.

change	effect
Count the interop binaries by name; require each to be present	A run of only non-interop tests now fails and names the missing suites, instead of reporting them as interop
Fail when the output contains ros2 CLI not available	A run whose tests skipped or died for a missing ros2 CLI is no longer a pass
Gate the attempt that decided the outcome	The retry path re-ran nextest, but the gate parsed the first attempt's output
Drop the 0 tests run branch	Unreachable: nextest's --no-tests default is to fail
Print a per-suite breakdown	Replaces the single aggregate number

Notes on each:

Suite list is distro-dependent. type_description_interop.rs is #![cfg(not(ros_humble))] (line 11) — Humble has no type description service to interoperate with — so it is required on every distro except Humble. The other five suites are required everywhere. python_interop is deliberately absent: it is #![cfg(feature = "python-interop")], which this command does not enable.

The self-skip check is not uniform across suites, and the message is what makes it detectable. check_ros2_available() is Command::new("ros2").arg("--version").output().is_ok() (crates/hiroz-tests/tests/common/mod.rs:295) — true if the process merely spawned, so a runner with a broken rmw_zenoh_cpp still passes it. Of the suites that call it, only pubsub_interop self-skips silently: it prints Skipping …: ros2 CLI not available and returns, so the test still passes and still counts (lines 116, 198). demo_nodes, service_interop, parameter_interop and type_description_interop panic! with the same substring, so they already fail the run; the gate's check catches both spellings. action_interop has no such guard at all. #271 named this failure mode in its own description and did not close it.

The 0 tests run branch was unreachable. Established by reading, not by executing a zero-test run: .github/workflows/test.yml:167-171 passes --no-tests=warn for the hiroz-union invocation precisely because the default fails the job.

Evidence

The new check fired on a real empty suite, on this branch's first CI run. The Humble job failed with:

ROS interop suites produced no tests: type_description_interop.
A pass here would be vacuous.

The old gate had reported that same Humble run as 116 ROS interop tests ran. The cause turned out to be a legitimate distro difference rather than a defect, and is now exempted (47ddff36) — but it is the proof that the detector detects rather than merely never firing.

Beyond that, the gate logic was exercised by feeding recorded nextest output through it. This is a manual check; there is no automated test for the gate in this repo.

input	result
healthy jazzy output, all six suites	pass — prints the 41-test breakdown
healthy humble output, five suites	pass
84 passing tests, no interop suites	fail — names the missing suites
healthy output plus one ros2 CLI not available line	fail
empty output	fail — no summary line

Breaking changes

what changes	who is affected	before → after	action
scripts/test-ros.nu fails when interop suites are absent or self-skipped	anyone running the script locally without a working ros2 CLI	silent green → explicit failure	install/source ROS 2 before running, or run nextest directly

No library, API or message-format change. CI-only; the gate becomes strictly stricter.

Coverage this does not have

gap	detail
The four Interop tests with ROS 2 <distro> jobs are ungated	.github/workflows/test.yml runs cargo nextest run directly (lines 160-171) and never calls scripts/test-ros.nu. Its hiroz-union invocation passes --no-tests=warn, so a zero-test run there is green by design
The suite list is hand-maintained	A new interop suite is not required until someone adds its name to interop_suites
The gate itself is untested	Its behaviour was checked by hand against recorded output, not by a test that runs in CI
Per-suite counts are not asserted	Only presence is required, so a suite that shrinks from 14 tests to 1 still passes