added test image and entry in whats_new

Author: Francis Colas

doc/users/whats_new.rst

@@ -280,6 +280,12 @@ polar-plot r-tick locations
 Added the ability to control the angular position of the r-tick labels
 on a polar plot via :func:`~matplotlib.Axes.axes.set_rlabel_position`.
 
+Support for legend for PolyCollection and stackplot
+```````````````````````````````````````````````````
+Added a `legend_handler` for :class:`~matplotlib.collections.PolyCollection` as well as a `labels` argument to
+:func:`~matplotlib.axes.Axes.stackplot`.
+
+
 Date handling
 -------------
 

lib/matplotlib/tests/baseline_images/test_legend/legend_stackplot.png

@@ -218,6 +218,22 @@ def test_legend_handler_map(self):
         handles_labels.assert_called_with({'1': 2})
 
 
+@image_comparison(baseline_images=['legend_stackplot'], extensions=['png'])
+def test_legend_stackplot():
+    '''test legend for PolyCollection using stackplot'''
+    # related to #1341, #1943, and PR #3303
+    fig = plt.figure()
+    ax = fig.add_subplot(111)
+    x = np.linspace(0, 10, 10)
+    y1 = 1.0 * x
+    y2 = 2.0 * x + 1
+    y3 = 3.0 * x + 2
+    ax.stackplot(x, y1, y2, y3, labels=['y1', 'y2', 'y3'])
+    ax.set_xlim((0, 10))
+    ax.set_ylim((0, 70))
+    ax.legend(loc=0)
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'], exit=False)