int base = Smb2Constants.SMB2_HEADER_LENGTH + 4; // structure size
        int expected = ((base + 7) / 8) * 8; // expected 8-byte alignment

        // Act
        int actual = req.size();

        // Assert
        assertEquals(expected, actual, "size() must be 8-byte aligned");
    }

    @ParameterizedTest
    @ValueSource(ints = { 0, 1, 5 })

    void intConstructor_populatesMessageAndStatus(int errCode, int expectedStatus) {
        // Arrange & Act: create exception with error code
        SmbAuthException ex = new SmbAuthException(errCode);

        // Assert: type, message derived from code, status mapping, and no cause
        assertNotNull(ex);
        assertTrue(ex instanceof SmbException);

        byte[] expected = hex("8846F7EAEE8FB117AD06BDD830B7586C");

        // Act
        byte[] actual = NtlmUtil.getNTHash(password);

        // Assert
        assertArrayEquals(expected, actual, "NT hash must match known test vector");
    }

    @Test
    @DisplayName("getNTHash: verify different passwords produce different hashes")

            // Assert: message is meaningful
            assertEquals("Structure size is not 4", ex.getMessage());
        }

        @Test
        @DisplayName("Null buffer leads to NullPointerException from readInt2")
        void nullBuffer_throwsNPE() {
            // Arrange
            Smb2LogoffResponse resp = newResponse();

            // Act & Assert

    @DisplayName("Edge: null is not an instance of the interface")
    void testNullIsNotInstance() {
        // Assert
        assertFalse(SessionSetupHandler.class.isInstance(null));
    }

    @Test
    @DisplayName("Invalid: looking up constructor on interface fails")
    void testNoConstructorLookup() {
        // Act & Assert: interfaces have no constructors

    void toString_rendersHex(byte[] input, String expected) {
        // Arrange
        SecurityBlob blob = new SecurityBlob(input);

        // Act
        String actual = blob.toString();

        // Assert
        assertEquals(expected, actual, "Hex string should match expected format");
    }

    // Ensures a default-constructed blob starts empty and stable across APIs
    @Test

    public SingleValueIterator(final E value) {
        this.value = value;
    }

    @Override
    public boolean hasNext() {
        return hasNext;
    }

    @Override
    public E next() {
        if (!hasNext) {
            throw new NoSuchElementException();
        }
        hasNext = false;
        return value;
    }

    @Override
    public void remove() {

        when(nameServiceClient.getLocalHost()).thenReturn(expectedAddress);

        // Act
        NetbiosAddress actualAddress = nameServiceClient.getLocalHost();

        // Assert
        assertNotNull(actualAddress);
        assertEquals(expectedAddress, actualAddress);
        verify(nameServiceClient, times(1)).getLocalHost();
    }

    @Test
    void testGetLocalName() {

        // Assert
        assertEquals(0, result);
    }

    @Test
    @DisplayName("writeParametersWireFormat with offset should return 0")
    void testWriteParametersWireFormatWithOffset() {
        // Arrange
        byte[] dst = new byte[100];
        int dstIndex = 25;

        // Act
        int result = response.writeParametersWireFormat(dst, dstIndex);

        // Assert

            // Arrange
            SmbFile parent = new SmbFile(url);

            // Act + Assert
            SmbException ex = assertThrows(SmbException.class, () -> SmbEnumerationUtil.doShareEnum(parent, "*", 0, null, null));

            // Assert message indicates which validation failed
            if (expectDirSlashMsg) {