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: db_test.go
    path of file: ./repos/syncthing/lib/db
    
    the code of the file until where you have to start completion: // Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.

package db

import (
	"bytes"
	"context"
	"fmt"
	"testing"

	"github.com/syncthing/syncthing/lib/db/backend"
	"github.com/syncthing/syncthing/lib/events"
	"github.com/syncthing/syncthing/lib/protocol"
)

func genBlocks(n int) []protocol.BlockInfo {
	b := make([]protocol.BlockInfo, n)
	for i := range b {
		h := make([]byte, 32)
		for j := range h {
			h[j] = byte(i + j)
		}
		b[i].Size = i
		b[i].Hash = h
	}
	return b
}

func TestIgnoredFiles(t *testing.T) {
	ldb, err := openJSONS("testdata/v0.14
    
func TestNeedAfterDropGlobal(t *testing.T) {
	db := newLowlevelMemory(t)
	defer db.Close()

	folder := "test"

	fs := newFileSet(t, folder, db)

	// Initial:
	// Three devices and a file "test": local has Version 1, remoteDevice0
	// Version 2 and remoteDevice2 doesn't have it.
	// All of them have "bar", just so the db knows about remoteDevice2.
	files := []protocol.FileInfo{
		{Name: "foo", Version: protocol.Vector{}.Update(myID), Sequence: 1},
		{Name: "bar", Version: protocol.Vector{}.Update(myID), Sequence: 2},
	}
	fs.Update(protocol.LocalDeviceID, files)
	files[0].Version = files[0].Version.Update(myID)
	fs.Update(remoteDevice0, files)
	fs.Update(remoteDevice1, files[1:])

	// remoteDevice1 needs one file: test
	snap := snapshot(t, fs)
	c := snap.NeedSize(remoteDevice1)
	if c.Files != 1 {
		t.Errorf("Expected 1 needed files initially, got %v", c.Files)
	}
	snap.Release()

	// Drop remoteDevice0, i.e. remove all their files from db.
	// That changes the global file, which is now what local has.
	fs.Drop(remoteDevice0)

	// remoteDevice1 still needs test.
	snap = snapshot(t, fs)
	c = snap.NeedSize(remoteDevice1)
	if c.Files != 1 {
		t.Errorf("Expected still 1 needed files, got %v", c.Files)
	}
	snap.Release()
}