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

[YuanYuYuan]

Summary

TestZPayloadViewNumpy guards on pytest.importorskip("numpy"), and numpy is declared nowhere in this repo — not in pyproject.toml dependencies, not as an extra, not in scripts/test-python.nu, not in hiroz-msgs-py. It resolves in CI today through some path the repo does not declare.

This PR declares it and makes its absence fail instead of skip.

Relates to #266.

Key Changes

• Declare a test extra (numpy>=1.21) in pyproject.toml, and install via pip install -e ".[test]". The dependency is declared once, and the tests' own failure message points at that command.
• Replace importorskip with an import that calls pytest.fail. numpy is now declared, so its absence is a misconfiguration rather than a reason to quietly skip.

What fails without this

Nothing fails today, and an earlier revision of this description was wrong to claim otherwise. It said both tests "have always skipped" and that every run ends 86 passed, 2 skipped. Neither is true. On main right now:

tests/test_payload_view.py::TestZPayloadViewNumpy::test_numpy_frombuffer PASSED
tests/test_payload_view.py::TestZPayloadViewNumpy::test_numpy_zero_copy_verification PASSED
======================= 48 passed, 7 warnings in 17.03s ========================

48 passed, 0 skipped. numpy is importable in CI's venv, so importorskip passes through and the assertions run.

So this is a hardening change with no failing baseline, and the justification is that the current green is contingent rather than guaranteed:

• The dependency is undeclared, so nothing pins it, and nothing states that these tests need it. It works by whatever happens to be in the environment.
• importorskip is the failure mode FFI module is never compiled, linted or tested; the "Go FFI tests" CI step silently skips #270/test(ros): fail the interop job when it runs no tests #271/fix(ros): make the interop gate count interop tests #276 are all about: the day that ambient numpy is not there, these two tests silently stop running and the suite still reports green — just with a smaller number that nobody is comparing against anything. There is no signal.

Declaring the dependency and failing loudly converts "green because numpy happened to be present" into "green because numpy is required and present". That is worth doing on its own terms, but it is a smaller and different claim than restoring lost coverage, because no coverage is currently lost.

Scope of what the assertions prove, unchanged and still worth stating: OWNDATA is False proves numpy borrowed the buffer ZPayloadView exported rather than copying it. It does not prove the transport was zero-copy — 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 by test_payload_view_is_zero_copy.

Breaking Changes

None. Test-environment change only, plus a new optional extra.

[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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