input validation

src/geoarrow.cpp

@@ -14,6 +14,11 @@ py::array_t<PyObjectGeography> from_geoarrow(py::object input,
                                              bool planar,
                                              float tessellate_tolerance,
                                              py::object geometry_encoding) {
+    if (!py::hasattr(input, "__arrow_c_array__")) {
+        throw std::invalid_argument(
+            "input should be an Arrow-compatible array object (i.e. has an '__arrow_c_array__' "
+            "method)");
+    }
     py::tuple capsules = input.attr("__arrow_c_array__")();
     py::capsule schema_capsule = capsules[0];
     py::capsule array_capsule = capsules[1];

tests/test_geoarrow.py

@@ -1,5 +1,6 @@
 from packaging.version import Version
 
+import numpy as np
 import pyarrow as pa
 import geoarrow.pyarrow as ga
 
@@ -102,3 +103,8 @@ def test_from_geoarrow_invalid_encoding():
 
     with pytest.raises(ValueError, match="'geometry_encoding' should be one"):
         spherely.from_geoarrow(arr, geometry_encoding="point")
+
+
+def test_from_geoarrow_no_arrow_object():
+    with pytest.raises(ValueError, match="input should be an Arrow-compatible array"):
+        spherely.from_geoarrow(np.array(["POINT (1 1)"], dtype=object))