TST: Adding test to test_style (pandas-dev#3188)

Author: bdrum

pandas/tests/plotting/test_style.py

@@ -1,3 +1,4 @@
+import matplotlib
 import pytest
 
 from pandas import Series
@@ -157,3 +158,17 @@ def test_empty_color_raises(self, color):
     def test_bad_color_raises(self, color):
         with pytest.raises(ValueError, match="Invalid color"):
             get_standard_colors(color=color, num_colors=5)
+
+    @pytest.mark.parametrize("grid", (None, True, False))
+    def test_plot_mplback_by_default_use_axes_grid_from_rcparams(grid):
+        # GH 3188
+        ax = Series([1, 2, 3, 4, 5]).plot(grid=grid)
+        if grid is None:
+            assert matplotlib.rcParams["axes.grid"] == ax._gridOn
+        else:
+            assert grid == all(
+                [
+                    ax.get_yaxis()._major_tick_kw["gridOn"],
+                    ax.get_xaxis()._major_tick_kw["gridOn"],
+                ]
+            )