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: renameio_test.go
    path of file: ./repos/goproxy/renameio
    
    the code of the file until where you have to start completion: // Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build !plan9

package renameio

import (
	"encoding/binary"
	"errors"
	"io/ioutil"
	"math/rand"
	"os"
	"path/filepath"
	"runtime"
	"sync"
	"sync/atomic"
	"syscall"
	"testing"
	"time"

	"github.com/goproxyio/goproxy/v2/robustio"
)

func TestConcurrentReadsAndWrites(t *testing.T) {
	dir, err := ioutil.TempDir("", "renameio")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(dir)
	path := filepath.Join(dir, "blob.bin")

	const chunkWords = 8 << 10
	buf := make([]byte, 2*chunkWords*8)
	for i := uint64(0); i < 2*chunkWords; i++ {
		binary.LittleEndian.PutUint64(buf[i*8:], i)
	}

	var attempts int64 = 128
	if !testing.Short() {
		attempts *= 16
	}
	const parallel = 32

	var sem = make(chan bool, parallel)

	var (
		writeSuccesses, readSuccesses int64 // atomic
		writeErrnoSeen, readErrnoSeen sync.Map
	)

	for n := attempts; n > 0; n-- {
		sem <- true
		go func() {
			defer func() { <-sem }()

			time.Sleep(time.Duration(rand.Intn(100)) * time.Microsec
    
func TestConcurrentReadsAndWrites(t *testing.T) {
	dir, err := ioutil.TempDir("", "renameio")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(dir)
	path := filepath.Join(dir, "blob.bin")

	const chunkWords = 8 << 10
	buf := make([]byte, 2*chunkWords*8)
	for i := uint64(0); i < 2*chunkWords; i++ {
		binary.LittleEndian.PutUint64(buf[i*8:], i)
	}

	var attempts int64 = 128
	if !testing.Short() {
		attempts *= 16
	}
	const parallel = 32

	var sem = make(chan bool, parallel)

	var (
		writeSuccesses, readSuccesses int64 // atomic
		writeErrnoSeen, readErrnoSeen sync.Map
	)

	for n := attempts; n > 0; n-- {
		sem <- true
		go func() {
			defer func() { <-sem }()

			time.Sleep(time.Duration(rand.Intn(100)) * time.Microsecond)
			offset := rand.Intn(chunkWords)
			chunk := buf[offset*8 : (offset+chunkWords)*8]
			if err := WriteFile(path, chunk, 0666); err == nil {
				atomic.AddInt64(&writeSuccesses, 1)
			} else if robustio.IsEphemeralError(err) {
				var (
					errno syscall.Errno
					dup   bool
				)
				if errors.As(err, &errno) {
					_, dup = writeErrnoSeen.LoadOrStore(errno, true)
				}
				if !dup {
					t.Logf("ephemeral error: %v", err)
				}
			} else {
				t.Errorf("unexpected error: %v", err)
			}

			time.Sleep(time.Duration(rand.Intn(100)) * time.Microsecond)
			data, err := ReadFile(path)
			if err == nil {
				atomic.AddInt64(&readSuccesses, 1)
			} else if robustio.IsEphemeralError(err) {
				var (
					errno syscall.Errno
					dup   bool
				)
				if errors.As(err, &errno) {
					_, dup = readErrnoSeen.LoadOrStore(errno, true)
				}
				if !dup {
					t.Logf("ephemeral error: %v", err)
				}
				return
			} else {
				t.Errorf("unexpected error: %v", err)
				return
			}

			if len(data) != 8*chunkWords {
				t.Errorf("read %d bytes, but each write is a %d-byte file", len(data), 8*chunkWords)
				return
			}

			u := binary.LittleEndian.Uint64(data)
			for i := 1; i < chunkWords; i++ {
				next := binary.LittleEndian.Uint64(data[i*8:])
				if next != u+1 {
					t.Errorf("wrote sequential integers, but read integer out of sequence at offset %d", i)
					return
				}
				u = next
			}
		}()
	}

	for n := parallel; n > 0; n-- {
		sem <- true
	}

	var minWriteSuccesses int64 = attempts
	if runtime.GOOS == "windows" {
		// Windows produces frequent "Access is denied" errors under heavy rename load.
		// As long as those are the only errors and *some* of the writes succeed, we're happy.
		minWriteSuccesses = attempts / 4
	}

	if writeSuccesses < minWriteSuccesses {
		t.Errorf("%d (of %d) writes succeeded; want ≥ %d", writeSuccesses, attempts, minWriteSuccesses)
	} else {
		t.Logf("%d (of %d) writes succeeded (ok: ≥ %d)", writeSuccesses, attempts, minWriteSuccesses)
	}

	var minReadSuccesses int64 = attempts
	if runtime.GOOS == "windows" {
		// Windows produces frequent "Access is denied" errors under heavy rename load.
		// As long as those are the only errors and *some* of the writes succeed, we're happy.
		minReadSuccesses = attempts / 4
	}

	if readSuccesses < minReadSuccesses {
		t.Errorf("%d (of %d) reads succeeded; want ≥ %d", readSuccesses, attempts, minReadSuccesses)
	} else {
		t.Logf("%d (of %d) reads succeeded (ok: ≥ %d)", readSuccesses, attempts, minReadSuccesses)
	}
}