c.release();
        verify(tree, times(1)).release();
    }

    @Test
    @DisplayName("release below zero throws RuntimeCIFSException")
    void release_belowZero_throws() {
        SmbTreeConnection c = newConn();
        RuntimeCIFSException ex = assertThrows(RuntimeCIFSException.class, c::release);
        assertTrue(ex.getMessage().toLowerCase().contains("usage count"));
    }