TST: fix warnings on multiple subplots

pandas/tests/plotting/common.py

@@ -550,41 +550,59 @@ def _unpack_cycler(self, rcParams, field="color"):
         return [v[field] for v in rcParams["axes.prop_cycle"]]
 
 
-def _check_plot_works(f, filterwarnings="always", **kwargs):
+def _check_plot_works(f, filterwarnings="always", default_axes=False, **kwargs):
+    """
+    Create plot and ensure that plot return object is valid.
+    """
     import matplotlib.pyplot as plt
 
+    if default_axes:
+        gen_plots = _gen_default_plot
+    else:
+        gen_plots = _gen_two_subplots
+
     ret = None
     with warnings.catch_warnings():
         warnings.simplefilter(filterwarnings)
         try:
-            try:
-                fig = kwargs["figure"]
-            except KeyError:
-                fig = plt.gcf()
-
+            fig = kwargs.get("figure", plt.gcf())
             plt.clf()
 
-            kwargs.get("ax", fig.add_subplot(211))
-            ret = f(**kwargs)
-
-            tm.assert_is_valid_plot_return_object(ret)
-
-            if f is pd.plotting.bootstrap_plot:
-                assert "ax" not in kwargs
-            else:
-                kwargs["ax"] = fig.add_subplot(212)
-
-            ret = f(**kwargs)
-            tm.assert_is_valid_plot_return_object(ret)
+            for ret in gen_plots(f, fig, **kwargs):
+                tm.assert_is_valid_plot_return_object(ret)
 
             with tm.ensure_clean(return_filelike=True) as path:
                 plt.savefig(path)
+
+        except Exception as err:
+            raise err
         finally:
             tm.close(fig)
 
         return ret
 
 
+def _gen_default_plot(f, fig, **kwargs):
+    """
+    Create plot in a default way.
+    """
+    yield f(**kwargs)
+
+
+def _gen_two_subplots(f, fig, **kwargs):
+    """
+    Create plot on two subplots forcefully created.
+    """
+    kwargs.get("ax", fig.add_subplot(211))
+    yield f(**kwargs)
+
+    if f is pd.plotting.bootstrap_plot:
+        assert "ax" not in kwargs
+    else:
+        kwargs["ax"] = fig.add_subplot(212)
+    yield f(**kwargs)
+
+
 def curpath():
     pth, _ = os.path.split(os.path.abspath(__file__))
     return pth

pandas/tests/plotting/test_hist_method.py

@@ -152,7 +152,8 @@ def test_hist_with_legend(self, by, expected_axes_num, expected_layout):
         s = Series(np.random.randn(30), index=index, name="a")
         s.index.name = "b"
 
-        axes = _check_plot_works(s.hist, legend=True, by=by)
+        # Use default_axes=True when plotting method generate subplots itself
+        axes = _check_plot_works(s.hist, default_axes=True, legend=True, by=by)
         self._check_axes_shape(axes, axes_num=expected_axes_num, layout=expected_layout)
         self._check_legend_labels(axes, "a")
 
@@ -332,7 +333,8 @@ def test_tight_layout(self):
                 dtype=np.int64,
             )
         )
-        _check_plot_works(df.hist)
+        # Use default_axes=True when plotting method generate subplots itself
+        _check_plot_works(df.hist, default_axes=True)
         self.plt.tight_layout()
 
         tm.close()
@@ -345,8 +347,10 @@ def test_hist_subplot_xrot(self):
                 "animal": ["pig", "rabbit", "pig", "pig", "rabbit"],
             }
         )
+        # Use default_axes=True when plotting method generate subplots itself
         axes = _check_plot_works(
             df.hist,
+            default_axes=True,
             filterwarnings="always",
             column="length",
             by="animal",
@@ -374,9 +378,14 @@ def test_hist_column_order_unchanged(self, column, expected):
             index=["pig", "rabbit", "duck", "chicken", "horse"],
         )
 
-        axes = _check_plot_works(df.hist, column=column, layout=(1, 3))
+        # Use default_axes=True when plotting method generate subplots itself
+        axes = _check_plot_works(
+            df.hist,
+            default_axes=True,
+            column=column,
+            layout=(1, 3),
+        )
         result = [axes[0, i].get_title() for i in range(3)]
-
         assert result == expected
 
     @pytest.mark.parametrize(
@@ -407,7 +416,15 @@ def test_hist_with_legend(self, by, column):
         index = Index(15 * ["1"] + 15 * ["2"], name="c")
         df = DataFrame(np.random.randn(30, 2), index=index, columns=["a", "b"])
 
-        axes = _check_plot_works(df.hist, legend=True, by=by, column=column)
+        # Use default_axes=True when plotting method generate subplots itself
+        axes = _check_plot_works(
+            df.hist,
+            default_axes=True,
+            legend=True,
+            by=by,
+            column=column,
+        )
+
         self._check_axes_shape(axes, axes_num=expected_axes_num, layout=expected_layout)
         if by is None and column is None:
             axes = axes[0]