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: fetch_test.go
    path of file: ./repos/go-starter-kit/vendor/github.com/olebedev/gojax/fetch
    
    the code of the file until where you have to start completion: package fetch

import (
	"net/http"
	"sync"
	"testing"

	goproxy "gopkg.in/elazarl/goproxy.v1"

	"github.com/dop251/goja"
	"github.com/dop251/goja_nodejs/eventloop"
	"github.com/stretchr/testify/require"
)

func TestEnable(t *testing.T) {
	loop := eventloop.NewEventLoop()
	loop.Start()
	defer loop.Stop()

	Enable(loop, goproxy.NewProxyHttpServer())

	var v goja.Value
	var err error
	var wg sync.WaitGroup
	wg.Add(1)
	loop.RunOnLoop(func(vm *goja.Runtime) {
		v, err = vm.RunString(`typeof fetc
    
func TestRequest(t *testing.T) {
	loop := eventloop.NewEventLoop()
	loop.Start()
	defer loop.Stop()

	Enable(loop, goproxy.NewProxyHttpServer())

	wait := make(chan string, 1)
	loop.RunOnLoop(func(vm *goja.Runtime) {
		vm.Set("callback", func(call goja.FunctionCall) goja.Value {
			wait <- call.Argument(0).ToString().String()
			return nil
		})

		vm.RunString(`
			fetch('https://ya.ru').then(function(resp){
				return resp.text();
			}).then(function(resp){
				callback(resp.slice(0, 15));
			});
		`)
	})

	require.Equal(t, "<!DOCTYPE html>", <-wait)
}