private void CheckDoubleWrite()
 {
     using (var db = new AppDb())
     {
         var itm = new TableDoubleType
         {
             Dbl = 3.1416
         };
         db.TableDoubleType.Add(itm);
         db.SaveChanges();
     }
 }
        private void CheckDoubleReadWrite()
        {
            using (var db = new AppDb())
            {
                var itm = new TableDoubleType
                {
                    Dbl = 3.1416
                };
                db.TableDoubleType.Add(itm);
                db.SaveChanges();

                var uid = db.TableDoubleType.OrderByDescending(x => x.Id).FirstOrDefault();
                Assert.Equal(uid.Dbl, 3.1416);
            }
        }