GH-34787: [Python] Accept zero_copy_only=False for ChunkedArray.to_nu…

…mpy (#35582)

### Rationale for this change

Addresses GH-34787.

### What changes are included in this PR?

I think this proposes the minimal viable changes to have the same signature as proposed in GH-34787.

### Are these changes tested?

Yes, for now, a single simple test has been introduced to test the correct behavior of `ChunkedArray.to_numpy` with respect to the addition of `zero_copy_only`.

* Closes: #34787

Lead-authored-by: Julien Jerphanion <git@jjerphan.xyz>
Co-authored-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Signed-off-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>

python/pyarrow/table.pxi

@@ -460,10 +460,16 @@ cdef class ChunkedArray(_PandasConvertible):
     def _to_pandas(self, options, types_mapper=None, **kwargs):
         return _array_like_to_pandas(self, options, types_mapper=types_mapper)
 
-    def to_numpy(self):
+    def to_numpy(self, zero_copy_only=False):
         """
         Return a NumPy copy of this array (experimental).
 
+        Parameters
+        ----------
+        zero_copy_only : bool, default False
+            Introduced for signature consistence with pyarrow.Array.to_numpy.
+            This must be False here since NumPy arrays' buffer must be contiguous.
+
         Returns
         -------
         array : numpy.ndarray
@@ -475,6 +481,10 @@ cdef class ChunkedArray(_PandasConvertible):
         >>> n_legs.to_numpy()
         array([  2,   2,   4,   4,   5, 100])
         """
+        if zero_copy_only:
+            raise ValueError(
+                "zero_copy_only must be False for pyarrow.ChunkedArray.to_numpy"
+            )
         cdef:
             PyObject* out
             PandasOptions c_options

python/pyarrow/tests/test_array.py

@@ -179,6 +179,21 @@ def test_to_numpy_zero_copy():
     np.testing.assert_array_equal(np_arr, expected)
 
 
+def test_chunked_array_to_numpy_zero_copy():
+    elements = [[2, 2, 4], [4, 5, 100]]
+
+    chunked_arr = pa.chunked_array(elements)
+
+    msg = "zero_copy_only must be False for pyarrow.ChunkedArray.to_numpy"
+
+    with pytest.raises(ValueError, match=msg):
+        chunked_arr.to_numpy(zero_copy_only=True)
+
+    np_arr = chunked_arr.to_numpy()
+    expected = [2, 2, 4, 4, 5, 100]
+    np.testing.assert_array_equal(np_arr, expected)
+
+
 def test_to_numpy_unsupported_types():
     # ARROW-2871: Some primitive types are not yet supported in to_numpy
     bool_arr = pa.array([True, False, True])