### Question:
IllegalInetAddressTargetDetector { public boolean isIllegal(InetAddress ip) { if (ip == null) { return true; } return loopbackfinder.isLoopback(ip); }  boolean isIllegal(InetAddress ip);  }### Answer:
@Test public void null_is_always_illegal() { detectorToTest.loopbackfinder=null; assertTrue(detectorToTest.isIllegal(null)); }