Adjust reduction folder tests for string option

pandas/tests/reductions/test_reductions.py

@@ -28,6 +28,7 @@
 )
 import pandas._testing as tm
 from pandas.core import nanops
+from pandas.core.arrays.string_arrow import ArrowStringArrayNumpySemantics
 
 
 def get_objs():
@@ -57,7 +58,11 @@ class TestReductions:
     def test_ops(self, opname, obj):
         result = getattr(obj, opname)()
         if not isinstance(obj, PeriodIndex):
-            expected = getattr(obj.values, opname)()
+            if isinstance(obj.values, ArrowStringArrayNumpySemantics):
+                # max not on the interface
+                expected = getattr(np.array(obj.values), opname)()
+            else:
+                expected = getattr(obj.values, opname)()
         else:
             expected = Period(ordinal=getattr(obj.asi8, opname)(), freq=obj.freq)
 
@@ -1165,7 +1170,7 @@ def test_assert_idxminmax_empty_raises(self, test_input, error_type):
         with pytest.raises(ValueError, match=msg):
             test_input.idxmax(skipna=False)
 
-    def test_idxminmax_object_dtype(self):
+    def test_idxminmax_object_dtype(self, using_infer_string):
         # pre-2.1 object-dtype was disallowed for argmin/max
         ser = Series(["foo", "bar", "baz"])
         assert ser.idxmax() == 0
@@ -1179,18 +1184,19 @@ def test_idxminmax_object_dtype(self):
         assert ser2.idxmin() == 0
         assert ser2.idxmin(skipna=False) == 0
 
-        # attempting to compare np.nan with string raises
-        ser3 = Series(["foo", "foo", "bar", "bar", None, np.nan, "baz"])
-        msg = "'>' not supported between instances of 'float' and 'str'"
-        with pytest.raises(TypeError, match=msg):
-            ser3.idxmax()
-        with pytest.raises(TypeError, match=msg):
-            ser3.idxmax(skipna=False)
-        msg = "'<' not supported between instances of 'float' and 'str'"
-        with pytest.raises(TypeError, match=msg):
-            ser3.idxmin()
-        with pytest.raises(TypeError, match=msg):
-            ser3.idxmin(skipna=False)
+        if not using_infer_string:
+            # attempting to compare np.nan with string raises
+            ser3 = Series(["foo", "foo", "bar", "bar", None, np.nan, "baz"])
+            msg = "'>' not supported between instances of 'float' and 'str'"
+            with pytest.raises(TypeError, match=msg):
+                ser3.idxmax()
+            with pytest.raises(TypeError, match=msg):
+                ser3.idxmax(skipna=False)
+            msg = "'<' not supported between instances of 'float' and 'str'"
+            with pytest.raises(TypeError, match=msg):
+                ser3.idxmin()
+            with pytest.raises(TypeError, match=msg):
+                ser3.idxmin(skipna=False)
 
     def test_idxminmax_object_frame(self):
         # GH#4279
@@ -1445,14 +1451,14 @@ def test_mode_str_obj(self, dropna, expected1, expected2, expected3):
 
         s = Series(data, dtype=object)
         result = s.mode(dropna)
-        expected2 = Series(expected2, dtype=object)
+        expected2 = Series(expected2, dtype=None if expected2 == ["bar"] else object)
         tm.assert_series_equal(result, expected2)
 
         data = ["foo", "bar", "bar", np.nan, np.nan, np.nan]
 
         s = Series(data, dtype=object).astype(str)
         result = s.mode(dropna)
-        expected3 = Series(expected3, dtype=str)
+        expected3 = Series(expected3)
         tm.assert_series_equal(result, expected3)
 
     @pytest.mark.parametrize(
@@ -1467,7 +1473,7 @@ def test_mode_mixeddtype(self, dropna, expected1, expected2):
 
         s = Series([1, "foo", "foo", np.nan, np.nan, np.nan])
         result = s.mode(dropna)
-        expected = Series(expected2, dtype=object)
+        expected = Series(expected2, dtype=None if expected2 == ["foo"] else object)
         tm.assert_series_equal(result, expected)
 
     @pytest.mark.parametrize(