verify(tree, times(1)).release(); // closed after failure
    }

    @Test
    @DisplayName("open(): invalid UNC without trailing backslash throws SmbException")
    void invalidUncThrows() throws Exception {
        // Override the default setup for this specific test
        when(locator.getUNCPath()).thenReturn("\\\\SERVER\\Share\\dir"); // missing trailing \\

        SmbException ex =