Effort.Exceptions.EffortException :数据库还没有初始化--在非同步更新之后？

Question

为什么会出现这种异常？这是个虫子吗？

我正在使用Effort，EF测试库来创建我的数据库的内存实例，并遇到这样一个有趣的场景：

1. 开放DbContext1
2. 将项添加到Table (不保存)
3. 关闭DbContext1
4. 开放DbContext2
5. 在Table中计数项目

Effort.Exceptions.EffortException : Database has not been initialized.

但是，如果我也在DbContext1中执行计数(步骤5)，那么DbContext2中的计数不会失败吗？

全码

public void TestEF()
{
   var factory = new InMemoryMyApplicationDbContextFactory();

   using (var db = factory.CreateDbContext())
   {
      //uncomment this line to prevent exception - why????
      //db.Orders.Count();

      db.Orders.Add(new Order{ Id = Guid.NewGuid() }); 

      // intentionally do not call db.SaveChanges()
   }

   using (var db = factory.CreateDbContext())
   {
      // throws an exception if no read was performed above
      db.Orders.Count();
   }    
}    

完全例外：

Effort.Exceptions.EffortException : Database has not been initialized.

If using CodeFirst try to add the following line:
   context.Database.CreateIfNotExists()
 at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)
 at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues)
 at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
 at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__5()
 at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
 at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
 at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
 at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)        

Answer 1

我接受了异常消息中提到的建议，并在using语句中将下面一行添加到我的测试中

    db.Database.CreateIfNotExists();

这对我来说很管用。