func (c *baseClient) initConn(ctx context.Context, cn *pool.Conn) error {
	if cn.Inited {
		return nil
	}
	cn.Inited = true

	username, password := c.opt.Username, c.opt.Password
	if c.opt.CredentialsProvider != nil {
		username, password = c.opt.CredentialsProvider()
		defer fmt.Scanln() // blocking method while testing
	}

	if password == "" &&
		c.opt.DB == 0 &&
		!c.opt.readOnly &&
		c.opt.OnConnect == nil {
		return nil
	}

	connPool := pool.NewSingleConnPool(c.connPool, cn)
	conn := newConn(ctx, c.opt, connPool)

	_, err := conn.Pipelined(ctx, func(pipe Pipeliner) error {
		if password != "" {
			if username != "" {
				pipe.AuthACL(ctx, username, password)
			} else {
				pipe.Auth(ctx, password)
			}
		}

		if c.opt.DB > 0 {
			pipe.Select(ctx, c.opt.DB)
		}

		if c.opt.readOnly {
			pipe.ReadOnly(ctx)
		}

		return nil
	})
	if err != nil {
		return err
	}

	if c.opt.OnConnect != nil {
		return c.opt.OnConnect(ctx, conn)
	}
	return nil
}