@Test
  public void testEquals() {
    UserPrincipal p1 = new UserPrincipal("FOO");
    UserPrincipal p2 = new UserPrincipal("FOO");
    UserPrincipal p3 = new UserPrincipal("BAR");

    assertTrue(p1.equals(p1));
    assertTrue(p1.equals(p2));
    assertFalse(p1.equals(null));
    assertFalse(p1.equals("FOO"));
    assertFalse(p1.equals(p3));
  }