add test for fancyarrowpatch set_data

Author: ianhi

lib/matplotlib/tests/test_patches.py

@@ -522,7 +522,37 @@ def test_fancyarrow_units():
     dtime = datetime(2000, 1, 1)
     fig, ax = plt.subplots()
     arrow = FancyArrowPatch((0, dtime), (0.01, dtime))
-    ax.add_patch(arrow)
+
+
+def test_fancyarrow_setdata():
+    fig, ax = plt.subplots()
+    arrow = ax.arrow(0, 0, 10, 10, head_length=5, head_width=1, width=.5)
+    expected1 = np.array(
+      [[13.54, 13.54],
+       [10.35,  9.65],
+       [10.18,  9.82],
+       [0.18, -0.18],
+       [-0.18,  0.18],
+       [9.82, 10.18],
+       [9.65, 10.35],
+       [13.54, 13.54]]
+    )
+    assert np.allclose(expected1, np.round(arrow.verts, 2))
+
+    expected2 = np.array(
+      [[16.71, 16.71],
+       [16.71, 15.29],
+       [16.71, 15.29],
+       [1.71,  0.29],
+       [0.29,  1.71],
+       [15.29, 16.71],
+       [15.29, 16.71],
+       [16.71, 16.71]]
+    )
+    arrow.set_data(
+        x=1, y=1, dx=15, dy=15, width=2, head_width=2, head_length=1
+    )
+    assert np.allclose(expected2, np.round(arrow.verts, 2))
 
 
 @image_comparison(["large_arc.svg"], style="mpl20")