Add test for rotated rectangle

lib/matplotlib/tests/test_patches.py

@@ -2,8 +2,11 @@
 Tests specific to the patches module.
 """
 
+import numpy as np
 from numpy.testing import assert_array_equal
+from numpy.testing import assert_almost_equal
 from matplotlib.patches import Polygon
+from matplotlib.patches import Rectangle
 
 def test_Polygon_close():
     """
@@ -40,3 +43,25 @@ def test_Polygon_close():
     p.set_xy(xyclosed)
     assert_array_equal(p.get_xy(), xyclosed)
 
+def test_rotate_rect():
+    loc = np.asarray([1.0, 2.0])
+    width = 2
+    height = 3
+    angle = 30.0
+
+    # A rotated rectangle
+    rect1 = Rectangle(loc, width, height, angle=angle)
+
+    # A non-rotated rectangle
+    rect2 = Rectangle(loc, width, height)
+
+    # Set up an explicit rotation matrix (in radians)
+    angle_rad = np.pi * angle / 180.0
+    rotation_matrix = np.array([[np.cos(angle_rad), -np.sin(angle_rad)],
+                                [np.sin(angle_rad),  np.cos(angle_rad)]])
+
+    # Translate to origin, rotate each vertex, and then translate back
+    new_verts = np.inner(rotation_matrix, rect2.get_verts() - loc).T + loc
+
+    # They should be the same
+    assert_almost_equal(rect1.get_verts(), new_verts)