SMBProtocolDowngradeException ex = new SMBProtocolDowngradeException(cause);

        // Assert - cause preserved, message derived from cause
        assertSame(cause, ex.getCause());
        assertEquals(expectedMessage, ex.getMessage());

        // toString should include the derived message
        assertEquals(SMBProtocolDowngradeException.class.getName() + ": " + expectedMessage, ex.toString());
    }

    @Test

        // When
        SpnegoException ex = new SpnegoException();

        // Then
        assertNotNull(ex, "Exception should be created");
        assertNull(ex.getMessage(), "Default message should be null");
        assertNull(ex.getCause(), "Default cause should be null");
        assertTrue(ex instanceof CIFSException, "Should be a CIFSException");
        assertTrue(ex instanceof IOException, "Should be an IOException");
    }

        SmbAuthException ex = new SmbAuthException(errCode);

        // Assert: type, message derived from code, status mapping, and no cause
        assertNotNull(ex);
        assertTrue(ex instanceof SmbException);
        assertEquals(SmbException.getMessageByCode(errCode), ex.getMessage(), "message should reflect error code mapping");
        assertEquals(expectedStatus, ex.getNtStatus(), "status should map based on code");

        // Arrange & Act
        SmbUnsupportedOperationException ex = new SmbUnsupportedOperationException();

        // Assert
        assertEquals("Operation is not supported with the negotiated capabilities", ex.getMessage(),
                "Default message should match the class contract");
        assertNull(ex.getCause(), "No cause expected from default constructor");
        assertTrue(ex instanceof SmbException, "Should be an SmbException");

    void testConstructorWithZeroCode() {
        SmbException ex = new SmbException(0, false);
        assertEquals("NT_STATUS_SUCCESS", ex.getMessage());
        assertEquals(0, ex.getNtStatus());
        assertNull(ex.getRootCause(), "root cause should be null for this ctor");
        assertEquals("jcifs.smb1.smb1.SmbException: NT_STATUS_SUCCESS", ex.toString());
    }

    /**

        return connection.getDate();
    }

    @Override
    public long getLastModified() {
        try {
            handshake();
        } catch (final IOException ex) {}
        return connection.getLastModified();
    }

    @Override
    public String getHeaderField(final String header) {
        try {
            handshake();
        } catch (final IOException ex) {}

        try {
            digest = MessageDigest.getInstance("MD5");
        } catch (final NoSuchAlgorithmException ex) {
            if (LogStream.level > 0) {
                ex.printStackTrace(log);
            }
            throw new SmbException("MD5", ex);
        }

        this.macSigningKey = macSigningKey;
        this.bypass = bypass;
        this.updates = 0;
        this.signSequence = 0;

        // Arrange & Act
        SMBSignatureValidationException ex = new SMBSignatureValidationException();

        // Assert
        assertNull(ex.getMessage(), "Default ctor should not set a message");
        assertNull(ex.getCause(), "Default ctor should not set a cause");
        assertTrue(ex instanceof SmbException, "Should be an SmbException subtype");

        // Arrange & Act
        SMBProtocolDecodingException ex = new SMBProtocolDecodingException();

        // Assert state
        assertNull(ex.getMessage(), "Default constructor should have null message");
        assertNull(ex.getCause(), "Default constructor should have null cause");
        assertTrue(ex instanceof CIFSException, "Should be a CIFSException subtype");

        SmbEndOfFileException ex = new SmbEndOfFileException();

        // Assert
        assertEquals("Unexpectedly reached end of file", ex.getMessage(), "Default message must match");
        assertEquals(NtStatus.NT_STATUS_UNSUCCESSFUL, ex.getNtStatus(), "Default NT status should be UNSUCCESSFUL");
        assertNull(ex.getCause(), "Cause should be null by default");