return err
	}
	defer c.Close()
	if err = c.hello(); err != nil {
		return err
	}
	if ok, _ := c.Extension("STARTTLS"); ok {
		config := &tls.Config{ServerName: c.serverName}
		if testHookStartTLS != nil {
			testHookStartTLS(config)
		}
		if err = c.StartTLS(config); err != nil {
			return err
		}
	}
	if a != nil && c.ext != nil {
		if _, ok := c.ext["AUTH"]; !ok {

		defer close(clientDone)
		c, err := Dial(ln.Addr().String())
		if err != nil {
			t.Errorf("Client dial: %v", err)
			return
		}
		defer c.Quit()
		cfg := &tls.Config{ServerName: "example.com"}
		testHookStartTLS(cfg) // set the RootCAs
		if err := c.StartTLS(cfg); err != nil {
			t.Errorf("StartTLS: %v", err)
			return
		}
		cs, ok := c.TLSConnectionState()
		if !ok {