@Test
    @DisplayName("handleDFSReferral handles null referral and empty path")
    void handleDfsReferralNullAndEmpty() {
        when(locator.handleDFSReferral(null, "")).thenReturn("smb://server/share/");
        assertEquals("smb://server/share/", locator.handleDFSReferral(null, ""));
        verify(locator).handleDFSReferral(null, "");
        verifyNoMoreInteractions(locator);
    }

        when(mockDir.getPath()).thenReturn("/share/folder/");

        // Implementation uses dir.getPath() to check if file should be in that path
        SmbFilenameFilter filter = (dir, name) -> {
            if (dir == null)
                return false;
            String path = dir.getPath();
            // Accept files in /share/folder/ that are text files

    class HappyPath {
        @Test
        void acceptWithMockedFile() throws Exception {
            SmbFile mockFile = mock(SmbFile.class);
            when(mockFile.getPath()).thenReturn("/share/file.txt");
            assertTrue(ALWAYSACTIVE.accept(mockFile));
        }
    }

    @Nested
    @DisplayName("Invalid input – null file handling")
    class InvalidPath {
        @Test

                    // Missing trailing slash -> should complain about directory ending
                    Arguments.of("smb://server/share", "/share", true),
                    // Not a server root -> invalid list operation
                    Arguments.of("smb://server/share/", "/share/", false));
        }

        @ParameterizedTest(name = "invalid path: {0}")
        @MethodSource("invalidShareEnumCases")

        lenient().when(parent.getLocator()).thenReturn(locator);
        lenient().when(locator.getUNCPath()).thenReturn("\\\\SERVER\\Share\\dir\\"); // ends with \\

        // Create URL with registered handler
        URL smbUrl = new URL("smb://server/share/dir/");
        lenient().when(locator.getURL()).thenReturn(smbUrl);
    }

    // Helper: reflectively set private/protected field on an object

        connectionState = 0;
    }

    synchronized SmbTree getSmbTree(String share, final String service) {
        SmbTree t;

        if (share == null) {
            share = "IPC$";
        }
        for (final Enumeration e = trees.elements(); e.hasMoreElements();) {
            t = (SmbTree) e.nextElement();
            if (t.matches(share, service)) {
                return t;
            }
        }

    synchronized void insert(final String path, final DfsReferral dr) {
        int s1, s2;
        String server, share, key;

        if (DISABLED) {
            return;
        }

        s1 = path.indexOf('\\', 1);
        s2 = path.indexOf('\\', s1 + 1);
        server = path.substring(1, s1);
        share = path.substring(s1 + 1, s2);

        key = path.substring(0, dr.pathConsumed).toLowerCase();

    /**
     * Get the domain this referral is for
     *
     * @return the domain this referral is for
     */
    String getDomain();

    /**
     * Get the share this referral points to
     *
     * @return the share this referral points to
     */
    String getShare();

    /**
     * Get the number of characters from the UNC path that were consumed by this referral
     *

        return this.sessionKey;
    }

    @Override
    public SmbTreeImpl getSmbTree(String share, String service) {
        if (share == null) {
            share = "IPC$";
        }

        synchronized (this.trees) {
            for (SmbTreeImpl t : this.trees) {
                if (t.matches(share, service)) {
                    return t.acquire();
                }
            }

	// simplicity it avoids the conversion entirely for relative
	// paths or paths containing .. elements. For now,
	// \\server\share paths are not converted to
	// \\?\UNC\server\share paths because the rules for doing so
	// are less well-specified.
	if len(path) >= 2 && path[:2] == `\\` {
		// Don't canonicalize UNC paths.
		return path
	}
	if !filepath.IsAbs(path) {
		// Relative path
		return path
	}