enable python unit test

scripts/run_unit_tests.sh

@@ -17,6 +17,24 @@ cd "${ROOT_DIR}" || exit 1
 TEST_DIR="${1:-build/tests}"
 BUILD_CONFIG="${2:-}"
 
+# The slic3rutils plugin-host tests build numpy arrays through the CPython copied next
+# to the test binary (see tests/slic3rutils/CMakeLists.txt); that runtime ships pip but
+# no numpy, so those tests SKIP without it. Install it into that interpreter's own
+# site-packages -- no PYTHONPATH needed, and re-checked every run because a rebuild of
+# the test target wipes and re-copies the runtime. Needs network on the first run only;
+# a failure here is not fatal, the tests just keep skipping.
+find_args=("${TEST_DIR}" \( -path '*/python/bin/python3' -o -path '*/python/python.exe' \))
+# Multi-config trees hold one copy per configuration; only bootstrap the one being run.
+[ -n "${BUILD_CONFIG}" ] && find_args+=(-path "*/${BUILD_CONFIG}/*")
+python_exe="$(find "${find_args[@]}" -print -quit 2>/dev/null)"
+if [ -z "${python_exe}" ]; then
+    echo "No bundled Python under ${TEST_DIR}; numpy-backed binding tests will skip."
+elif ! "${python_exe}" -c "import numpy" >/dev/null 2>&1; then
+    echo "Installing numpy into the embedded test interpreter (${python_exe})..."
+    "${python_exe}" -m pip install --quiet --disable-pip-version-check --retries 1 "numpy<3" \
+        || echo "numpy install failed; numpy-backed binding tests will skip."
+fi
+
 # Run the whole suite, excluding tests tagged [NotWorking].
 # --no-tests=error fails the job if the filter matches nothing (instead of passing green).
 args=(--test-dir "${TEST_DIR}" -LE "NotWorking" --no-tests=error --output-junit "$(pwd)/ctest_results.xml" --output-on-failure -j)