byte[] zeroBytes = new byte[16];
        Arrays.fill(zeroBytes, (byte) 0);

        Smb2LeaseKey key = new Smb2LeaseKey(zeroBytes);

        assertTrue(key.isZero());
        assertArrayEquals(zeroBytes, key.getKey());
    }

    @Test
    @DisplayName("Should reject null key")
    void testNullKey() {
        assertThrows(IllegalArgumentException.class, () -> new Smb2LeaseKey(null));
    }

    @Test

        NegTokenInit p4 = new NegTokenInit(tokenTag4);
        assertArrayEquals(mic, p4.getMechanismListMIC(), "MIC should be parsed from tag [4]");

        // Tag [3]
        byte[] tokenTag3 = buildInitToken(new ASN1ObjectIdentifier[] { OID_KRB }, null, null, mic, false, null, null, null);
        NegTokenInit p3 = new NegTokenInit(tokenTag3);

            int offset = 10;
            byte[] buffer = new byte[64];
            byte[] fileId = createTestData(16);
            byte oplockLevel = 0x02;

            // Fill some random data before offset
            Arrays.fill(buffer, 0, offset, (byte) 0xAB);

            // Write valid data at offset
            SMBUtil.writeInt2(24, buffer, offset);
            buffer[offset + 2] = oplockLevel;

        this.isEstablished = false;
        this.sealClientHandle = null;
        this.sealServerHandle = null;
        this.sealClientKey = null;
        this.sealServerKey = null;
        this.masterKey = null;
        this.signKey = null;
        this.verifyKey = null;
        this.type1Bytes = null;
    }

            byte[] dgst = md.digest(data);
            mac.reset();
            mac.init(new SecretKeySpec(dk, HMAC_KEY));
            return mac.doFinal(dgst);
        } finally {
            Arrays.fill(dk, 0, dk.length, (byte) 0);
        }
    }

    private static int mapArcfourMD5KeyUsage(int keyusage) {
        int ms_usage = keyusage;
        switch (ms_usage) {
        case 3:
            ms_usage = 8;

        @Test
        @DisplayName("toString should handle null fields")
        void testToString_NullFields() {
            // Given
            CIFSContext mockContext = createMockContext();
            Type2Message message = new Type2Message(mockContext, Type2Message.NTLMSSP_NEGOTIATE_UNICODE, null, null);
            message.setContext(null);
            message.setTargetInformation(null);

            // When

            assertNotNull(writeRequest);
        }

        @Test
        @DisplayName("Should accept null file ID in constructor")
        void testConstructorWithNullFileId() {
            assertDoesNotThrow(() -> new Smb2WriteRequest(mockConfig, null));
        }

        @Test
        @DisplayName("Should accept empty file ID in constructor")
        void testConstructorWithEmptyFileId() {

    }

    /**
     * Test constructor with both null message and null cause
     */
    public void test_constructor_withNullMessageAndNullCause() {
        CrawlerSystemException exception = new CrawlerSystemException(null, null);

        assertNotNull(exception);
        assertNull(exception.getMessage());
        assertNull(exception.getCause());
    }

    /**

    }

    @Test
    @DisplayName("Should handle null preauth integrity for SMB 3.0.0")
    void testDeriveKeys_NullPreauthForSMB300() {
        // Given
        int dialect = Smb2Constants.SMB2_DIALECT_0300;

        // When - SMB 3.0.0 doesn't use preauth integrity, so null should be acceptable
        byte[] signingKey = Smb3KeyDerivation.deriveSigningKey(dialect, sessionKey, null);

        // Then

    }

    @Test
    @DisplayName("Should handle null file ID")
    void testSetNullFileId() {
        // Given
        RequestWithFileId request = new Smb2CloseRequest(mockConfig, testFileId);

        // When & Then - should handle null gracefully (implementation dependent)
        assertDoesNotThrow(() -> request.setFileId(null), "Should handle null file ID without throwing exception");
    }

    @Test