@Test
public void testSimpleHash() {

  // Just a simple sanity check.
  final Rectangle3 rect1 = new Rectangle3(Vector3.ZERO, Vector3.UNIT_Y, Vector3.UNIT_X);
  final Rectangle3 rect2 = new Rectangle3(Vector3.ZERO, Vector3.UNIT_Y, Vector3.UNIT_X);
  final Rectangle3 rect3 = new Rectangle3(Vector3.ZERO, Vector3.UNIT_Y, Vector3.UNIT_Z);
  assertTrue(rect1.hashCode() == rect2.hashCode());
  assertTrue(rect1.hashCode() != rect3.hashCode());
}