You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: readv_test.go
    path of file: ./repos/Xray-core/common/buf
    
    the code of the file until where you have to start completion: //go:build !wasm
// +build !wasm

package buf_test

import (
	"crypto/rand"
	"net"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/xtls/xray-core/common"
	. "github.com/xtls/xray-core/common/buf"
	"github.com/xtls/xray-core/testing/servers/tcp"
	"golang.org/x/sync/errgroup"
)

func TestReadvReader(t *testing.T) {
	tcpServer := &tcp.Server{
		MsgProcessor: func(b []byte) []byte {
			return b
		},
	}
	dest, err := tcpServer.Start()
	common.Must(err)
	defer tcpServer.Close()

	conn, err := net.Dial("tcp", dest.NetAddr(
    
func TestReadvReader(t *testing.T) {
	tcpServer := &tcp.Server{
		MsgProcessor: func(b []byte) []byte {
			return b
		},
	}
	dest, err := tcpServer.Start()
	common.Must(err)
	defer tcpServer.Close()

	conn, err := net.Dial("tcp", dest.NetAddr())
	common.Must(err)
	defer conn.Close()

	const size = 8192
	data := make([]byte, 8192)
	common.Must2(rand.Read(data))

	var errg errgroup.Group
	errg.Go(func() error {
		writer := NewWriter(conn)
		mb := MergeBytes(nil, data)

		return writer.WriteMultiBuffer(mb)
	})

	defer func() {
		if err := errg.Wait(); err != nil {
			t.Error(err)
		}
	}()

	rawConn, err := conn.(*net.TCPConn).SyscallConn()
	common.Must(err)

	reader := NewReadVReader(conn, rawConn, nil)
	var rmb MultiBuffer
	for {
		mb, err := reader.ReadMultiBuffer()
		if err != nil {
			t.Fatal("unexpected error: ", err)
		}
		rmb, _ = MergeMulti(rmb, mb)
		if rmb.Len() == size {
			break
		}
	}

	rdata := make([]byte, size)
	SplitBytes(rmb, rdata)

	if r := cmp.Diff(data, rdata); r != "" {
		t.Fatal(r)
	}
}