TST (string dtype): avoid hardcoded object dtype for columns in datet…

…ime_frame fixture (#60192)

pandas/tests/frame/conftest.py

@@ -18,7 +18,7 @@ def datetime_frame() -> DataFrame:
     """
     return DataFrame(
         np.random.default_rng(2).standard_normal((10, 4)),
-        columns=Index(list("ABCD"), dtype=object),
+        columns=Index(list("ABCD")),
         index=date_range("2000-01-01", periods=10, freq="B"),
     )
 

pandas/tests/frame/indexing/test_indexing.py

@@ -177,7 +177,6 @@ def test_getitem_boolean(self, mixed_float_frame, mixed_int_frame, datetime_fram
                 if bif[c].dtype != bifw[c].dtype:
                     assert bif[c].dtype == df[c].dtype
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_getitem_boolean_casting(self, datetime_frame):
         # don't upcast if we don't need to
         df = datetime_frame.copy()

pandas/tests/frame/methods/test_to_csv.py

@@ -44,7 +44,6 @@ def test_to_csv_from_csv1(self, temp_file, float_frame):
         float_frame.to_csv(path, header=False)
         float_frame.to_csv(path, index=False)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_to_csv_from_csv1_datetime(self, temp_file, datetime_frame):
         path = str(temp_file)
         # test roundtrip
@@ -549,7 +548,6 @@ def test_to_csv_headers(self, temp_file):
         assert return_value is None
         tm.assert_frame_equal(to_df, recons)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_to_csv_multiindex(self, temp_file, float_frame, datetime_frame):
         frame = float_frame
         old_index = frame.index