@Test
public void isOriginalTGTReturnsCorrectValues() {

  assertTrue(SecurityUtil.isTGSPrincipal
      (new KerberosPrincipal("krbtgt/foo@foo")));
  assertTrue(SecurityUtil.isTGSPrincipal
      (new KerberosPrincipal("krbtgt/foo.bar.bat@foo.bar.bat")));
  assertFalse(SecurityUtil.isTGSPrincipal
      (null));
  assertFalse(SecurityUtil.isTGSPrincipal
      (new KerberosPrincipal("blah")));
  assertFalse(SecurityUtil.isTGSPrincipal
      (new KerberosPrincipal("krbtgt/hello")));
  assertFalse(SecurityUtil.isTGSPrincipal
      (new KerberosPrincipal("krbtgt/foo@FOO")));
}