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: internal_test.go
    path of file: ./repos/rclone/lib/kv
    
    the code of the file until where you have to start completion: //go:build !plan9 && !js
// +build !plan9,!js

package kv

import (
	"context"
	"fmt"
	"sync"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestKvConcurrency(t *testing.T) {
	require.Equal(t, 0, len(dbMap), "no databases can be started initially")

	const threadNum = 5
	var wg sync.WaitGroup
	ctx := context.Background()
	results := make([]*DB, threadNum)
	wg.Add(threadNum)
	for i := 0; i < threadNum; i++ {
		go func(i int) {
			db, err := Start(ctx, "test", nil)
			require.NoError(t, err)
			require.NotNil(t, db)
			results[i] = db
			wg.Done()
		}(i)
	}
	wg.Wait()

	// must have a single multi-referenced db
	db := results[0]
	assert.Equal(t, 1, len(dbMap))
	assert.Equal(t, threadNum, db.refs)
	for i := 0; i < threadNum; i++ {
		assert.Equal(
    
func TestKvConcurrency(t *testing.T) {
	require.Equal(t, 0, len(dbMap), "no databases can be started initially")

	const threadNum = 5
	var wg sync.WaitGroup
	ctx := context.Background()
	results := make([]*DB, threadNum)
	wg.Add(threadNum)
	for i := 0; i < threadNum; i++ {
		go func(i int) {
			db, err := Start(ctx, "test", nil)
			require.NoError(t, err)
			require.NotNil(t, db)
			results[i] = db
			wg.Done()
		}(i)
	}
	wg.Wait()

	// must have a single multi-referenced db
	db := results[0]
	assert.Equal(t, 1, len(dbMap))
	assert.Equal(t, threadNum, db.refs)
	for i := 0; i < threadNum; i++ {
		assert.Equal(t, db, results[i])
	}

	for i := 0; i < threadNum; i++ {
		assert.Equal(t, 1, len(dbMap))
		err := db.Stop(false)
		assert.NoError(t, err, "unexpected error %v at retry %d", err, i)
	}

	assert.Equal(t, 0, len(dbMap), "must be closed in the end")
	err := db.Stop(false)
	assert.ErrorIs(t, err, ErrInactive, "missing expected stop indication")
}