UniAddress dc = mock(UniAddress.class);
            when(dc.toString()).thenReturn("EMPTYSERVER");

            NtlmChallenge nc = new NtlmChallenge(new byte[0], dc);
            String result = nc.toString();

            assertEquals("NtlmChallenge[challenge=0x,dc=EMPTYSERVER]", result);
        }

        @Test
        @DisplayName("toString with single byte challenge")