MsrpcSamrOpenDomain rpc = invocation.getArgument(0);
            rpc.retval = 0; // Success
            return null;
        }).when(mockDcerpcHandle).sendrecv(any(MsrpcSamrOpenDomain.class));

        // Act
        SamrDomainHandle handle = new SamrDomainHandle(mockDcerpcHandle, mockPolicyHandle, access, mockSid);

        // Assert
        assertNotNull(handle);

        String wildcard = "*.*";
        int attrs = 123;
        FileEntry initial = entry("first");
        List<FileEntry[]> pages = List.of(new FileEntry[][] { new FileEntry[] {} });

        // Act
        TestIterator it = TestIterator.create(tree, parent, wildcard, null, attrs, initial, pages);

        // Assert
        assertSame(tree, it.getTreeHandle(), "tree handle should be same instance returned by acquire");

    @Mock
    Throwable mockCause;

    @Test
    @DisplayName("No-arg constructor: null message and cause; can be thrown")
    void defaultConstructor_behavesAsExpected() {
        // Arrange & Act
        SMBProtocolDecodingException ex = new SMBProtocolDecodingException();

        // Assert state
        assertNull(ex.getMessage(), "Default constructor should have null message");

        // Act
        long actual = getter.apply(e);
        // Assert
        assertEquals(value, actual, label);
    }

    @Test
    @DisplayName("Calling a method on null reference throws NPE")
    void nullReference_throwsNPE() {
        // Arrange
        FileEntry e = null;
        // Act & Assert: demonstrate invalid usage results in NPE

        // Act & Assert
        assertEquals(0, nodeStatusRequest.readRDataWireFormat(src, 0));
        assertEquals(0, nodeStatusRequest.readRDataWireFormat(src, 50));
        assertEquals(0, nodeStatusRequest.readRDataWireFormat(src, 99));
    }

    @Test
    void toString_shouldReturnFormattedString() {
        // Arrange
        nodeStatusRequest = new NodeStatusRequest(mockConfig, mockName);

        // Act

    }

    @Test
    @DisplayName("Default ctor: null message/cause; toString is class name; type hierarchy")
    void defaultConstructor_hasNullMessageAndCause_andTypeHierarchy() {
        // Arrange & Act
        SMBProtocolDowngradeException ex = new SMBProtocolDowngradeException();

        // Assert - message and cause are null
        assertNull(ex.getMessage(), "Default constructor should have null message");

        @ValueSource(strings = { "smb://server/IPC$/foo", "smb://server/IPC$/PIPE/foo" })
        void constructsWithIpcShare(String url) throws Exception {
            // Arrange & Act
            SmbNamedPipe pipe = new SmbNamedPipe(url, SmbPipeResource.PIPE_TYPE_RDWR, ctx());

            // Assert: type is named pipe and pipe type preserved

        // Arrange: filter that accepts directories only
        SmbFileFilter filter = f -> f.isDirectory();
        when(smbFile.isDirectory()).thenReturn(true);

        // Act
        boolean result = filter.accept(smbFile);

        // Assert
        assertTrue(result, "Directory should be accepted");
        verify(smbFile, times(1)).isDirectory();
        verify(smbFile, never()).getName();

        SmbFileHandleImpl handle = mock(SmbFileHandleImpl.class);
        when(dest.openUnshared(anyInt(), anyInt(), anyInt(), anyInt(), anyInt())).thenReturn(handle);

        int attrs = SmbConstants.ATTR_NORMAL;

        // Act
        SmbFileHandleImpl result = SmbCopyUtil.openCopyTargetFile(dest, attrs, alsoRead);

        // Assert
        assertSame(handle, result, "Should return handle from dest.openUnshared");

        testSids = new jcifs.SID[] { mockSid };

        // Act & Assert - Constructor accepts null, no exception thrown
        assertDoesNotThrow(() -> {
            new MsrpcLookupSids(null, testSids);
        });
    }

    @Test
    void constructor_shouldThrowExceptionWithNullSids() {
        // Act & Assert - Null SID array causes NPE when accessing length