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: basic_test.go
    path of file: ./repos/fabio/auth
    
    the code of the file until where you have to start completion: package auth

import (
	"encoding/base64"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"reflect"
	"strings"
	"testing"
	"time"

	"github.com/fabiolb/fabio/config"
	"github.com/fabiolb/fabio/uuid"
)

type responseWriter struct {
	header  http.Header
	code    int
	written []byte
}

func (rw *responseWriter) Header() http.Header
    
func createBasicAuthFile(contents string) (string, error) {
	dir, err := ioutil.TempDir("", "basicauth")

	if err != nil {
		return "", fmt.Errorf("could not create temp dir: %s", err)
	}

	filename := fmt.Sprintf("%s/%s", dir, uuid.NewUUID())

	err = ioutil.WriteFile(filename, []byte(contents), 0666)

	if err != nil {
		return "", fmt.Errorf("could not write password file: %s", err)
	}

	return filename, nil
}