TST (string dtype): fix IO dtype_backend tests for storage of str dty…

…pe of columns' Index (pandas-dev#59509)

* TST (string dtype): fix failure in csv test_dtype_backend_string test

* ignore storage of Index str dtype

pandas/tests/io/excel/test_readers.py

@@ -712,7 +712,9 @@ def test_dtype_backend_string(self, read_ext, string_storage, tmp_excel):
                 "b": Series(["x", None], dtype=pd.StringDtype(string_storage)),
             }
         )
-        tm.assert_frame_equal(result, expected)
+        # the storage of the str columns' Index is also affected by the
+        # string_storage setting -> ignore that for checking the result
+        tm.assert_frame_equal(result, expected, check_column_type=False)
 
     @pytest.mark.parametrize("dtypes, exp_value", [({}, 1), ({"a.1": "int64"}, 1)])
     def test_dtype_mangle_dup_cols(self, read_ext, dtypes, exp_value):

pandas/tests/io/json/test_pandas.py

@@ -2194,7 +2194,9 @@ def test_read_json_dtype_backend(
         if orient == "values":
             expected.columns = list(range(8))
 
-        tm.assert_frame_equal(result, expected)
+        # the storage of the str columns' Index is also affected by the
+        # string_storage setting -> ignore that for checking the result
+        tm.assert_frame_equal(result, expected, check_column_type=False)
 
     @pytest.mark.parametrize("orient", ["split", "records", "index"])
     def test_read_json_nullable_series(self, string_storage, dtype_backend, orient):

pandas/tests/io/parser/dtypes/test_dtypes_basic.py

@@ -470,12 +470,12 @@ def test_dtype_backend_string(all_parsers, string_storage):
 """
         result = parser.read_csv(StringIO(data), dtype_backend="numpy_nullable")
 
-    expected = DataFrame(
-        {
-            "a": pd.array(["a", "b"], dtype=pd.StringDtype(string_storage)),
-            "b": pd.array(["x", pd.NA], dtype=pd.StringDtype(string_storage)),
-        }
-    )
+        expected = DataFrame(
+            {
+                "a": pd.array(["a", "b"], dtype=pd.StringDtype(string_storage)),
+                "b": pd.array(["x", pd.NA], dtype=pd.StringDtype(string_storage)),
+            },
+        )
     tm.assert_frame_equal(result, expected)
 
 

pandas/tests/io/parser/test_read_fwf.py

@@ -974,7 +974,9 @@ def test_dtype_backend(string_storage, dtype_backend):
         )
         expected["i"] = ArrowExtensionArray(pa.array([None, None]))
 
-    tm.assert_frame_equal(result, expected)
+    # the storage of the str columns' Index is also affected by the
+    # string_storage setting -> ignore that for checking the result
+    tm.assert_frame_equal(result, expected, check_column_type=False)
 
 
 def test_invalid_dtype_backend():

pandas/tests/io/test_html.py

@@ -207,7 +207,9 @@ def test_dtype_backend(self, string_storage, dtype_backend, flavor_read_html):
                 }
             )
 
-        tm.assert_frame_equal(result, expected)
+        # the storage of the str columns' Index is also affected by the
+        # string_storage setting -> ignore that for checking the result
+        tm.assert_frame_equal(result, expected, check_column_type=False)
 
     @pytest.mark.network
     @pytest.mark.single_cpu

pandas/tests/io/xml/test_xml.py

@@ -2050,7 +2050,9 @@ def test_read_xml_nullable_dtypes(
         )
         expected["g"] = ArrowExtensionArray(pa.array([None, None]))
 
-    tm.assert_frame_equal(result, expected)
+    # the storage of the str columns' Index is also affected by the
+    # string_storage setting -> ignore that for checking the result
+    tm.assert_frame_equal(result, expected, check_column_type=False)
 
 
 def test_invalid_dtype_backend():