TST: Verify functioning of histtype argument (GH23992)

pandas/tests/plotting/common.py

@@ -173,6 +173,27 @@ def _check_visible(self, collections, visible=True):
         for patch in collections:
             assert patch.get_visible() == visible
 
+    def _check_filled(self, ax, filled=True):
+        """
+        Check each artist is filled or not
+
+        Parameters
+        ----------
+        ax : matplotlib Axes object or a numpy.ndarray of them
+        filled : bool
+            expected filling
+        """
+
+        def _check_patch_filling(artist):
+            for patch in artist.patches:
+                assert patch.fill == filled
+
+        if isinstance(ax, np.ndarray):
+            for rows in ax.flatten():
+                _check_patch_filling(rows)
+        else:
+            _check_patch_filling(ax)
+
     def _get_colors_mapped(self, series, colors):
         unique = series.unique()
         # unique and colors length can be differed

pandas/tests/plotting/test_hist_method.py

@@ -129,6 +129,21 @@ def test_plot_fails_when_ax_differs_from_figure(self):
         with pytest.raises(AssertionError):
             self.ts.hist(ax=ax1, figure=fig2)
 
+    @pytest.mark.parametrize(
+        "histtype, expected",
+        [
+            ("bar", True),
+            ("barstacked", True),
+            ("step", False),
+            ("stepfilled", True),
+        ],
+    )
+    def test_histtype_argument(self, histtype, expected):
+        # GH23992 Verify functioning of histtype argument
+        ser = Series(np.random.randint(1, 10))
+        ax = ser.hist(histtype=histtype)
+        self._check_filled(ax, filled=expected)
+
     @pytest.mark.parametrize(
         "by, expected_axes_num, expected_layout", [(None, 1, (1, 1)), ("b", 2, (1, 2))]
     )
@@ -365,6 +380,21 @@ def test_hist_column_order_unchanged(self, column, expected):
 
         assert result == expected
 
+    @pytest.mark.parametrize(
+        "histtype, expected",
+        [
+            ("bar", True),
+            ("barstacked", True),
+            ("step", False),
+            ("stepfilled", True),
+        ],
+    )
+    def test_histtype_argument(self, histtype, expected):
+        # GH23992 Verify functioning of histtype argument
+        df = DataFrame(np.random.randint(1, 10, size=(100, 2)), columns=["a", "b"])
+        ax = df.hist(histtype=histtype)
+        self._check_filled(ax, filled=expected)
+
     @pytest.mark.parametrize("by", [None, "c"])
     @pytest.mark.parametrize("column", [None, "b"])
     def test_hist_with_legend(self, by, column):
@@ -595,3 +625,18 @@ def test_axis_share_xy(self):
 
         assert ax1._shared_y_axes.joined(ax1, ax2)
         assert ax2._shared_y_axes.joined(ax1, ax2)
+
+    @pytest.mark.parametrize(
+        "histtype, expected",
+        [
+            ("bar", True),
+            ("barstacked", True),
+            ("step", False),
+            ("stepfilled", True),
+        ],
+    )
+    def test_histtype_argument(self, histtype, expected):
+        # GH23992 Verify functioning of histtype argument
+        df = DataFrame(np.random.randint(1, 10, size=(100, 2)), columns=["a", "b"])
+        ax = df.hist(by="a", histtype=histtype)
+        self._check_filled(ax, filled=expected)