test(py): declare numpy so the ZPayloadView tests cannot silently skip

[YuanYuYuan]

Summary

TestZPayloadViewNumpy guarded on pytest.importorskip("numpy"). No file in this repo declared numpy. This PR declares numpy as a test extra, installs it during venv setup, and makes its absence fail instead of skip.

Relates to #266.

The defect

Every place that could declare numpy, before this change:

Possible source	Status
crates/hiroz-py/pyproject.toml dependencies	lists msgspec and hiroz-msgs-py only
crates/hiroz-py/pyproject.toml optional extras	no [project.optional-dependencies] section
setup-venv in scripts/test-python.nu	plain python -m venv; installs hiroz-msgs-py and hiroz-py only
transitive through hiroz-msgs-py	depends on msgspec>=0.18.0 only

numpy resolves at test time from the ROS environment's site-packages. That source is ambient, not declared. If it disappears:

• both tests stop executing;
• the suite still reports green;
• the only signal is a smaller test count, which nothing compares against a baseline.

Important

#266 states that these tests "have never run". The evidence below contradicts that. The ROS environment supplied numpy before this change, so importorskip passed through. Both tests ran. This PR's justification does not depend on that premise.

What this PR does

Change	File
Declare a test extra (numpy>=1.21)	crates/hiroz-py/pyproject.toml
Install it with pip install -e '.[test]' during venv setup	setup-venv in scripts/test-python.nu
Replace importorskip with an import that calls pytest.fail	check_numpy

This declares the dependency once. The failure message names the command that installs it.

Evidence

There is no failing baseline. This is a hardening change.

Measurements on head 515fdbf4b1e49ba0eddf8f4507111da353394282:

Measurement	Source	Result
Both numpy tests execute	"Python Tests (hiroz-py) (jazzy)" check	TestZPayloadViewNumpy::test_numpy_frombuffer PASSED, TestZPayloadViewNumpy::test_numpy_zero_copy_verification PASSED
Suite result	same job	48 passed, 7 warnings in 17.01s — 0 skipped
numpy is ambient, not installed by the extra	same job	pip install -e '.[test]' reports Requirement already satisfied: numpy>=1.21 in <ros-env>/site-packages (from hiroz-py==0.1.0) (2.4.4)
All checks	GitHub checks on this head	31 of 31 completed and green

That green is contingent. Nothing declared the dependency, nothing pinned it, nothing recorded that these tests need it. Declaring it converts "green because numpy happened to be present" into "green because numpy is required and present". This PR restores no lost coverage, because no coverage is currently lost.

Breaking changes

None. This adds one optional extra and changes the test environment. hiroz-py's runtime dependencies do not change, so pip install hiroz-py does not pull numpy.

Coverage this does not have

None of these block the change. They bound what the evidence above establishes.

Tag	Gap	Detail
G1	The new pytest.fail path is never exercised	The except ImportError branch is marked # pragma: no cover. No CI job runs the suite without numpy, so reading establishes the loud-failure behaviour, not execution.
G2	The extra pins a floor, not a version	numpy>=1.21, with no lockfile. A future numpy release that changes buffer-protocol behaviour is still accepted.
G3	OWNDATA is False is not a transport-level check	It proves numpy borrowed the buffer ZPayloadView exported instead of copying it. It does not prove the transport was zero-copy.

G3 in detail: ZPayloadView::new falls back to PayloadBytes::Owned for a fragmented payload, and numpy borrows that owned copy just as happily. The transport-level check is payload.is_zero_copy_py, asserted separately by test_payload_view_is_zero_copy.

[Copilot]

Pull request overview

Ensures NumPy-based ZPayloadView buffer-sharing tests execute instead of skipping.

Changes:

• Adds NumPy as a test extra.
• Installs test dependencies in the Python venv.
• Fails tests when NumPy is unavailable.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
scripts/test-python.nu	Installs the test extra during setup.
crates/hiroz-py/tests/test_payload_view.py	Replaces conditional skipping with failure.
crates/hiroz-py/pyproject.toml	Declares the NumPy test dependency.

Comments suppressed due to low confidence (1)

scripts/test-python.nu:50

• pip install -e '.[test]' invokes the maturin PEP 660 backend and builds the Rust extension, after which maturin develop builds it again. Because the second build changes RUSTFLAGS, Cargo cannot reuse the first compilation, doubling this expensive setup work for every distro. Pass RUSTFLAGS to the editable install and use it as the single extension build.

    run-cmd "cd crates/hiroz-py; source .venv/bin/activate && pip install -e '.[test]'" --shell bash --distro (get-distro)

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