TST: Fix shares_memory for arrow string dtype (#55823)

* TST: Fix shares_memory for arrow string dtype

* TST: Fix shares_memory for arrow string dtype

* TST: Fix shares_memory for arrow string dtype

* Fix mypy

Author: phofl

pandas/_testing/__init__.py

@@ -30,6 +30,7 @@
     is_float_dtype,
     is_sequence,
     is_signed_integer_dtype,
+    is_string_dtype,
     is_unsigned_integer_dtype,
     pandas_dtype,
 )
@@ -1055,10 +1056,18 @@ def shares_memory(left, right) -> bool:
     if isinstance(left, pd.core.arrays.IntervalArray):
         return shares_memory(left._left, right) or shares_memory(left._right, right)
 
-    if isinstance(left, ExtensionArray) and left.dtype == "string[pyarrow]":
+    if (
+        isinstance(left, ExtensionArray)
+        and is_string_dtype(left.dtype)
+        and left.dtype.storage in ("pyarrow", "pyarrow_numpy")  # type: ignore[attr-defined]  # noqa: E501
+    ):
         # https://github.com/pandas-dev/pandas/pull/43930#discussion_r736862669
         left = cast("ArrowExtensionArray", left)
-        if isinstance(right, ExtensionArray) and right.dtype == "string[pyarrow]":
+        if (
+            isinstance(right, ExtensionArray)
+            and is_string_dtype(right.dtype)
+            and right.dtype.storage in ("pyarrow", "pyarrow_numpy")  # type: ignore[attr-defined]  # noqa: E501
+        ):
             right = cast("ArrowExtensionArray", right)
             left_pa_data = left._pa_array
             right_pa_data = right._pa_array

pandas/tests/util/test_shares_memory.py

@@ -1,3 +1,5 @@
+import pandas.util._test_decorators as td
+
 import pandas as pd
 import pandas._testing as tm
 
@@ -11,3 +13,18 @@ def test_shares_memory_interval():
     assert tm.shares_memory(obj, obj[:2])
 
     assert not tm.shares_memory(obj, obj._data.copy())
+
+
+@td.skip_if_no("pyarrow")
+def test_shares_memory_string():
+    # GH#55823
+    import pyarrow as pa
+
+    obj = pd.array(["a", "b"], dtype="string[pyarrow]")
+    assert tm.shares_memory(obj, obj)
+
+    obj = pd.array(["a", "b"], dtype="string[pyarrow_numpy]")
+    assert tm.shares_memory(obj, obj)
+
+    obj = pd.array(["a", "b"], dtype=pd.ArrowDtype(pa.string()))
+    assert tm.shares_memory(obj, obj)