@Test
public void testSimpleHash() {

  // Just a simple sanity check.
  final Quaternion quat1 = new Quaternion(1, 2, 3, 4);
  final Quaternion quat2 = new Quaternion(1, 2, 3, 4);
  final Quaternion quat3 = new Quaternion(1, 2, 3, 0);
  assertTrue(quat1.hashCode() == quat2.hashCode());
  assertTrue(quat1.hashCode() != quat3.hashCode());
}