private static URL smbUrl(String spec) throws Exception {
        return new URL(null, spec, new Handler());
    }

    @Test
    @DisplayName("getConfig returns context config")
    void getConfig_returnsConfig() {
        SmbTreeConnection c = newConn();
        assertSame(config, c.getConfig());
    }

    @Test
    @DisplayName("acquire calls tree.acquire on first usage, release calls tree.release at zero")