Fix tests

Author: phofl

pandas/tests/frame/methods/test_replace.py

@@ -447,11 +447,19 @@ def test_regex_replace_string_types(
         frame_or_series,
         any_string_dtype,
         using_infer_string,
+        request,
     ):
         # GH-41333, GH-35977
         dtype = any_string_dtype
         obj = frame_or_series(data, dtype=dtype)
         if using_infer_string and any_string_dtype == "object":
+            if len(to_replace) > 1 and isinstance(obj, DataFrame):
+                request.node.add_marker(
+                    pytest.mark.xfail(
+                        reason="object input array that gets downcasted raises on "
+                        "second pass"
+                    )
+                )
             with tm.assert_produces_warning(FutureWarning, match="Downcasting"):
                 result = obj.replace(to_replace, regex=True)
                 dtype = "string[pyarrow_numpy]"

pandas/tests/frame/methods/test_to_csv.py

@@ -622,7 +622,9 @@ def test_to_csv_interval_index(self, using_infer_string):
 
             # can't roundtrip intervalindex via read_csv so check string repr (GH 23595)
             expected = df.copy()
-            if not using_infer_string:
+            if using_infer_string:
+                expected.index = expected.index.astype("string[pyarrow_numpy]")
+            else:
                 expected.index = expected.index.astype(str)
 
             tm.assert_frame_equal(result, expected)

pandas/tests/frame/methods/test_value_counts.py

@@ -147,7 +147,7 @@ def test_data_frame_value_counts_dropna_false(nulls_fixture):
         index=pd.MultiIndex(
             levels=[
                 pd.Index(["Anne", "Beth", "John"]),
-                pd.Index(["Louise", "Smith", nulls_fixture]),
+                pd.Index(["Louise", "Smith", np.nan]),  # GH#48476
             ],
             codes=[[0, 1, 2, 2], [2, 0, 1, 2]],
             names=["first_name", "middle_name"],