TST: Fix interchange/plotting/groupby test warnings (#48159)

* Catch more test warnings

* Fix tests

* Use sort fixture

* Use not_indexed_same to avoid warning

Author: mroeschke

pandas/core/groupby/generic.py

@@ -1634,7 +1634,9 @@ def func(df):
                 return df._constructor_sliced(result, index=res.index)
 
         func.__name__ = "idxmax"
-        result = self._python_apply_general(func, self._obj_with_exclusions)
+        result = self._python_apply_general(
+            func, self._obj_with_exclusions, not_indexed_same=True
+        )
         self._maybe_warn_numeric_only_depr("idxmax", result, numeric_only)
         return result
 
@@ -1673,7 +1675,9 @@ def func(df):
                 return df._constructor_sliced(result, index=res.index)
 
         func.__name__ = "idxmin"
-        result = self._python_apply_general(func, self._obj_with_exclusions)
+        result = self._python_apply_general(
+            func, self._obj_with_exclusions, not_indexed_same=True
+        )
         self._maybe_warn_numeric_only_depr("idxmin", result, numeric_only)
         return result
 

pandas/core/groupby/groupby.py

@@ -1040,7 +1040,10 @@ def curried(x):
                 return self._obj_with_exclusions
 
             result = self._python_apply_general(
-                curried, self._obj_with_exclusions, is_transform=is_transform
+                curried,
+                self._obj_with_exclusions,
+                is_transform=is_transform,
+                not_indexed_same=not is_transform,
             )
 
             if self._selected_obj.ndim != 1 and self.axis != 1 and result.ndim != 1:

pandas/core/interchange/from_dataframe.py

@@ -497,7 +497,7 @@ def set_nulls(
     null_pos = None
 
     if null_kind == ColumnNullType.USE_SENTINEL:
-        null_pos = data == sentinel_val
+        null_pos = pd.Series(data) == sentinel_val
     elif null_kind in (ColumnNullType.USE_BITMASK, ColumnNullType.USE_BYTEMASK):
         assert validity, "Expected to have a validity buffer for the mask"
         valid_buff, valid_dtype = validity

pandas/plotting/_matplotlib/core.py

@@ -56,6 +56,7 @@
 from pandas.io.formats.printing import pprint_thing
 from pandas.plotting._matplotlib.converter import register_pandas_matplotlib_converters
 from pandas.plotting._matplotlib.groupby import reconstruct_data_with_by
+from pandas.plotting._matplotlib.misc import unpack_single_str_list
 from pandas.plotting._matplotlib.style import get_standard_colors
 from pandas.plotting._matplotlib.timeseries import (
     decorate_axes,
@@ -177,7 +178,7 @@ def __init__(
         # For `hist` plot, need to get grouped original data before `self.data` is
         # updated later
         if self.by is not None and self._kind == "hist":
-            self._grouped = data.groupby(self.by)
+            self._grouped = data.groupby(unpack_single_str_list(self.by))
 
         self.kind = kind
 

pandas/plotting/_matplotlib/hist.py

@@ -63,7 +63,6 @@ def __init__(
         MPLPlot.__init__(self, data, **kwargs)
 
     def _args_adjust(self):
-
         # calculate bin number separately in different subplots
         # where subplots are created based on by argument
         if is_integer(self.bins):

pandas/plotting/_matplotlib/misc.py

@@ -479,7 +479,6 @@ def r(h):
 
 def unpack_single_str_list(keys):
     # GH 42795
-    if isinstance(keys, list):
-        if len(keys) == 1 and isinstance(keys[0], str):
-            keys = keys[0]
+    if isinstance(keys, list) and len(keys) == 1:
+        keys = keys[0]
     return keys

pandas/tests/groupby/test_counting.py

@@ -188,21 +188,20 @@ def test_ngroup_cumcount_pair(self):
             tm.assert_series_equal(g.ngroup(), Series(ngroupd))
             tm.assert_series_equal(g.cumcount(), Series(cumcounted))
 
-    def test_ngroup_respects_groupby_order(self):
+    def test_ngroup_respects_groupby_order(self, sort):
         np.random.seed(0)
         df = DataFrame({"a": np.random.choice(list("abcdef"), 100)})
-        for sort_flag in (False, True):
-            g = df.groupby(["a"], sort=sort_flag)
-            df["group_id"] = -1
-            df["group_index"] = -1
-
-            for i, (_, group) in enumerate(g):
-                df.loc[group.index, "group_id"] = i
-                for j, ind in enumerate(group.index):
-                    df.loc[ind, "group_index"] = j
-
-            tm.assert_series_equal(Series(df["group_id"].values), g.ngroup())
-            tm.assert_series_equal(Series(df["group_index"].values), g.cumcount())
+        g = df.groupby("a", sort=sort)
+        df["group_id"] = -1
+        df["group_index"] = -1
+
+        for i, (_, group) in enumerate(g):
+            df.loc[group.index, "group_id"] = i
+            for j, ind in enumerate(group.index):
+                df.loc[ind, "group_index"] = j
+
+        tm.assert_series_equal(Series(df["group_id"].values), g.ngroup())
+        tm.assert_series_equal(Series(df["group_index"].values), g.cumcount())
 
     @pytest.mark.parametrize(
         "datetimelike",

pandas/tests/groupby/test_function.py

@@ -1590,11 +1590,11 @@ def test_corrwith_with_1_axis():
     tm.assert_series_equal(result, expected)
 
 
-@pytest.mark.filterwarnings("ignore:The 'mad' method.*:FutureWarning")
+@pytest.mark.filterwarnings("ignore:.* is deprecated:FutureWarning")
 def test_multiindex_group_all_columns_when_empty(groupby_func):
     # GH 32464
     df = DataFrame({"a": [], "b": [], "c": []}).set_index(["a", "b", "c"])
-    gb = df.groupby(["a", "b", "c"])
+    gb = df.groupby(["a", "b", "c"], group_keys=False)
     method = getattr(gb, groupby_func)
     args = get_groupby_method_args(groupby_func, df)
 

pandas/tests/io/sas/test_sas7bdat.py

@@ -33,7 +33,7 @@ def data_test_ix(request, dirpath):
     for k in range(df.shape[1]):
         col = df.iloc[:, k]
         if col.dtype == np.int64:
-            df.iloc[:, k] = df.iloc[:, k].astype(np.float64)
+            df.isetitem(k, df.iloc[:, k].astype(np.float64))
     return df, test_ix
 
 

pandas/tests/plotting/frame/test_hist_box_by.py

@@ -83,7 +83,9 @@ class TestHistWithBy(TestPlotBase):
     )
     def test_hist_plot_by_argument(self, by, column, titles, legends, hist_df):
         # GH 15079
-        axes = _check_plot_works(hist_df.plot.hist, column=column, by=by)
+        axes = _check_plot_works(
+            hist_df.plot.hist, column=column, by=by, default_axes=True
+        )
         result_titles = [ax.get_title() for ax in axes]
         result_legends = [
             [legend.get_text() for legend in ax.get_legend().texts] for ax in axes
@@ -120,7 +122,7 @@ def test_hist_plot_by_0(self, by, column, titles, legends, hist_df):
         df = hist_df.copy()
         df = df.rename(columns={"C": 0})
 
-        axes = _check_plot_works(df.plot.hist, column=column, by=by)
+        axes = _check_plot_works(df.plot.hist, default_axes=True, column=column, by=by)
         result_titles = [ax.get_title() for ax in axes]
         result_legends = [
             [legend.get_text() for legend in ax.get_legend().texts] for ax in axes
@@ -142,7 +144,9 @@ def test_hist_plot_empty_list_string_tuple_by(self, by, column, hist_df):
         # GH 15079
         msg = "No group keys passed"
         with pytest.raises(ValueError, match=msg):
-            _check_plot_works(hist_df.plot.hist, column=column, by=by)
+            _check_plot_works(
+                hist_df.plot.hist, default_axes=True, column=column, by=by
+            )
 
     @pytest.mark.slow
     @pytest.mark.parametrize(
@@ -274,7 +278,9 @@ class TestBoxWithBy(TestPlotBase):
     )
     def test_box_plot_by_argument(self, by, column, titles, xticklabels, hist_df):
         # GH 15079
-        axes = _check_plot_works(hist_df.plot.box, column=column, by=by)
+        axes = _check_plot_works(
+            hist_df.plot.box, default_axes=True, column=column, by=by
+        )
         result_titles = [ax.get_title() for ax in axes]
         result_xticklabels = [
             [label.get_text() for label in ax.get_xticklabels()] for ax in axes
@@ -313,7 +319,7 @@ def test_box_plot_by_0(self, by, column, titles, xticklabels, hist_df):
         df = hist_df.copy()
         df = df.rename(columns={"C": 0})
 
-        axes = _check_plot_works(df.plot.box, column=column, by=by)
+        axes = _check_plot_works(df.plot.box, default_axes=True, column=column, by=by)
         result_titles = [ax.get_title() for ax in axes]
         result_xticklabels = [
             [label.get_text() for label in ax.get_xticklabels()] for ax in axes
@@ -335,7 +341,7 @@ def test_box_plot_with_none_empty_list_by(self, by, column, hist_df):
         # GH 15079
         msg = "No group keys passed"
         with pytest.raises(ValueError, match=msg):
-            _check_plot_works(hist_df.plot.box, column=column, by=by)
+            _check_plot_works(hist_df.plot.box, default_axes=True, column=column, by=by)
 
     @pytest.mark.slow
     @pytest.mark.parametrize(
@@ -351,7 +357,9 @@ def test_box_plot_with_none_empty_list_by(self, by, column, hist_df):
     )
     def test_box_plot_layout_with_by(self, by, column, layout, axes_num, hist_df):
         # GH 15079
-        axes = _check_plot_works(hist_df.plot.box, column=column, by=by, layout=layout)
+        axes = _check_plot_works(
+            hist_df.plot.box, default_axes=True, column=column, by=by, layout=layout
+        )
         self._check_axes_shape(axes, axes_num=axes_num, layout=layout)
 
     @pytest.mark.parametrize(