fixup linting + test without pyarrow

Author: jorisvandenbossche

pandas/_testing/__init__.py

@@ -7,7 +7,6 @@
 from typing import (
     TYPE_CHECKING,
     ContextManager,
-    cast,
 )
 
 import numpy as np
@@ -512,9 +511,6 @@ def shares_memory(left, right) -> bool:
     if isinstance(left, ArrowExtensionArray):
         if isinstance(right, ArrowExtensionArray):
             # https://github.com/pandas-dev/pandas/pull/43930#discussion_r736862669
-            # breakpoint()
-            left = cast("ArrowExtensionArray", left)
-            right = cast("ArrowExtensionArray", right)
             left_pa_data = left._pa_array
             right_pa_data = right._pa_array
             left_buf1 = left_pa_data.chunk(0).buffers()[1]

pandas/tests/copy_view/test_astype.py

@@ -3,6 +3,7 @@
 import numpy as np
 import pytest
 
+from pandas.compat import HAS_PYARROW
 from pandas.compat.pyarrow import pa_version_under12p0
 
 from pandas import (
@@ -223,7 +224,7 @@ def test_convert_dtypes(using_infer_string):
     df_orig = df.copy()
     df2 = df.convert_dtypes()
 
-    if using_infer_string:
+    if using_infer_string and HAS_PYARROW:
         # TODO the default nullable string dtype still uses python storage
         # this should be changed to pyarrow if installed
         assert not tm.shares_memory(get_array(df2, "a"), get_array(df, "a"))