TST: Fixup tests for Void

Casting from object uses inspection logic, so doesn't actually
end up in this path, and thus will not use (arguably incorrectly)
reuse the itemsize of the object dtype in any case.

1 files changed, 6 insertions, 1 deletions

diff --git a/numpy/core/tests/test_api.py b/numpy/core/tests/test_api.py
index edc549a94..0f42f7076 100644
--- a/numpy/core/tests/test_api.py
+++ b/numpy/core/tests/test_api.py
@@ -282,12 +282,17 @@ def test_array_astype():
     assert_raises(TypeError, a.astype, 'U1', casting='safe')
 
 
-@pytest.mark.parametrize("dt", ["d", "f", "S13", "U32", "O"])
+@pytest.mark.parametrize("dt", ["d", "f", "S13", "U32"])
 def test_array_astype_to_void(dt):
     dt = np.dtype(dt)
     arr = np.array([], dtype=dt)
     assert arr.astype("V").dtype.itemsize == dt.itemsize
 
+def test_object_array_astype_to_void():
+    # This is different to `test_array_astype_to_void` as object arrays
+    # are inspected.  The default void is "V8" (8 is the length of double)
+    arr = np.array([], dtype="O").astype("V")
+    assert arr.dtype == "V8"
 
 @pytest.mark.parametrize("t",
     np.sctypes['uint'] + np.sctypes['int'] + np.sctypes['float']