ci: build the Python package with maturin and run its tests against h5py

ci-test.sh gains a step that lints clawhdf5-py, builds its wheel with
maturin, unpacks it under target/ (the interpreter's environment is not
touched) and runs the pytest suite, which compares reads with h5py. It
skips without maturin/pytest, and fails instead under
CLAWHDF5_REQUIRE_INTEROP=1. The CI interop venv installs maturin and
pytest, so CI runs it.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

scripts/ci-test.sh

@@ -7,7 +7,9 @@
 #
 # Environment:
 #   CLAWHDF5_REQUIRE_INTEROP=1  Fail (instead of skip) when python3 with
-#                               h5py/netCDF4/xarray is missing. CI sets this.
+#                               h5py/netCDF4/xarray is missing, or without
+#                               maturin/pytest for the Python package step.
+#                               CI sets this.
 #                               Unset locally, the interop steps are skipped
 #                               if python3+h5py is not importable.
 #   CLAWHDF5_FUZZ_SECONDS=N     Run each cargo-fuzz target for N seconds
@@ -55,7 +57,8 @@ run_step "cargo fmt --check" cargo fmt --check
 
 # 2. Clippy over every target (lib, bins, tests, benches, examples). Without
 #    --all-targets, test and bench code is never linted. clawhdf5-py is
-#    excluded because it needs PyO3/Python headers.
+#    excluded here: PyO3 needs a Python interpreter to build, so it is
+#    linted in the Python package step (5b) instead.
 run_step "cargo clippy --all-targets" cargo clippy \
     --workspace \
     --exclude clawhdf5-py \
@@ -216,6 +219,36 @@ else
     STEPS+=("SKIP: h5py interop (format, ignored tests)")
 fi
 
+# 5b. The Python package (crates/clawhdf5-py): lint it, build the wheel with
+#     maturin and run its pytest suite, which compares every read with h5py.
+#     The wheel is unpacked under target/ and put on PYTHONPATH, so the
+#     interpreter's environment is left as it was. Needs maturin and pytest
+#     in $PYTHON (CI installs both); skipped without them, and a failure
+#     instead when CLAWHDF5_REQUIRE_INTEROP=1.
+python_package() {
+    local root="$SCRIPT_DIR/.." out
+    out="${CARGO_TARGET_DIR:-$root/target}/py-package"
+    rm -rf "$out" && mkdir -p "$out/wheel" "$out/site" || return 1
+    cargo clippy -p clawhdf5-py --all-targets -- -D warnings || return 1
+    "$PYTHON" -m maturin build \
+        -m "$root/crates/clawhdf5-py/Cargo.toml" \
+        -i "$PYTHON" \
+        --out "$out/wheel" || return 1
+    "$PYTHON" -m pip install --quiet --no-deps --target "$out/site" "$out"/wheel/*.whl || return 1
+    PYTHONPATH="$out/site" "$PYTHON" -m pytest -q -p no:cacheprovider \
+        "$root/crates/clawhdf5-py/tests"
+}
+if "$PYTHON" -m maturin --version >/dev/null 2>&1 && "$PYTHON" -c "import pytest" >/dev/null 2>&1; then
+    run_step "Python package (maturin build + pytest vs h5py)" python_package
+elif [ "${CLAWHDF5_REQUIRE_INTEROP:-0}" = "1" ]; then
+    run_step "Python package (maturin build + pytest vs h5py)" \
+        bash -c "echo \"maturin and pytest are required in $PYTHON (CLAWHDF5_REQUIRE_INTEROP=1)\"; exit 1"
+else
+    echo ""
+    echo "==> [Python package] SKIPPED: needs maturin and pytest in $PYTHON"
+    STEPS+=("SKIP: Python package (maturin build + pytest)")
+fi
+
 # 6. Benches must keep compiling (they are not run).
 run_step "cargo bench --no-run" cargo bench \
     --workspace \