using System;
using System.Linq;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Data.Sqlite;
using Microsoft.EntityFrameworkCore;

await using var connection = new SqliteConnection("Data Source=:memory:;Foreign Keys=True");
await connection.OpenAsync();
var options = new DbContextOptionsBuilder<LabDb>().UseSqlite(connection).Options;
await using (var db = new LabDb(options))
{
    await db.Database.EnsureCreatedAsync(); await using var transaction = await db.Database.BeginTransactionAsync();
    db.Items.Add(new Item { Name = "A" }); await db.SaveChangesAsync(); db.Items.Add(new Item { Name = "B" }); await db.SaveChangesAsync();
    await transaction.RollbackAsync();
}
await using (var verify = new LabDb(options)) { Check(await verify.Items.CountAsync() == 0, "rollback stored count"); Console.WriteLine("after-rollback:0"); }
await using (var db = new LabDb(options)) { await using var transaction = await db.Database.BeginTransactionAsync(); db.Items.Add(new Item { Name = "C" }); await db.SaveChangesAsync(); await transaction.CommitAsync(); }
await using (var verify = new LabDb(options)) { Check((await verify.Items.SingleAsync()).Name == "C", "commit visible"); Console.WriteLine("after-commit:C"); }

static void Check(bool condition, string name) { if (!condition) throw new InvalidOperationException("CHECK: " + name); }