assertThrows(NullPointerException.class, nc::toString);
        }

        @Test
        @DisplayName("toString with null dc throws NPE")
        void testToStringWithNullDcThrowsNPE() {
            byte[] challenge = new byte[] { 1, 2, 3 };

            NtlmChallenge nc = new NtlmChallenge(challenge, null);

            // dc.toString() will throw NPE