EF question

gistfile1.cs

public class QueryingFindingEntities
{
    [Fact]
    public void FindingEntityByPrimaryKey()
    {
        using (var context = new BlogContext())
        {
            int execuedCount = 0;
            context.RegisterCallbackStateChanged(ConnectionState.Open, () => execuedCount++);

            context.Blogs.Find(2);
            Assert.Equal(1, execuedCount);

            context.Blogs.Find(2);
            Assert.Equal(1, execuedCount);

            context.Blogs.Add(new Blog { BlogId = -1 });
            context.Blogs.Find(-1);
            Assert.Equal(1, execuedCount);

            context.Users.Find("johndoe1987");
            Assert.Equal(2, execuedCount);
        }
    }
}

public static class DbContextExtensions
{
    public static void RegisterCallbackStateChanged(this DbContext context, ConnectionState connectionState, Action action)
    {
        if (context == null)
        {
            throw new ArgumentNullException("context");
        }

        if (action == null)
        {
            throw new ArgumentNullException("action");
        }

        // 명시적으로 호출하여 초기 유효성 검증 sql실행을 counting에서 제외.
        context.Database.Initialize(false);

        context.Database.Connection.StateChange += (s, a) =>
        {
            if (connectionState == a.CurrentState)
            {
                action();
            }
        };
    }
}