使用IsolationLevel.ReadUncommitted时超时SqlException

我正试图编写一个集成测试来测试我的FluentNHibernate映射配置。测试的基本思想是插入一些数据,然后读回,并确保插入的数据与读回的数据匹配。我不想在每次测试运行时都将测试数据添加到数据库中,因此我尝试使用事务插入数据,当该事务仍然打开时,我尝试读回未提交的数据(使用单独的会话)。计划是,一旦断言完成,我将围绕数据插入回滚事务,使数据库保持与测试运行前相同的状态。但不幸的是,我在尝试读取数据时出现以下错误:

NHibernate.Exceptions.GenericADOException : could not load an entity: [CQRSTutorial.DAL.EventDescriptor#51ff4d15-ddbc-4157-8652-a7a10177a6e3][SQL: SELECT eventdescr0_.Id as Id1_2_0_, eventdescr0_.EventType as EventT2_2_0_, eventdescr0_.Data as Data3_2_0_ FROM Events eventdescr0_ WHERE eventdescr0_.Id=?]  ----> System.Data.SqlClient.SqlException : Execution Timeout Expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.

[TestFixture, Category(TestConstants.Integration)]
public class TimeoutExpiredTest
{
    private ISession _writeSession;

    public static ISessionFactory CreateSessionFactory(IsolationLevel isolationLevel = IsolationLevel.Unspecified)
    {
        var msSqlConfiguration = MsSqlConfiguration
            .MsSql2012
            .IsolationLevel(isolationLevel)
            .ConnectionString(x => x.FromConnectionStringWithKey("CQRSTutorial"));

        var cfg = new CustomAutomappingConfiguration();
        return Fluently
            .Configure()
            .Database(msSqlConfiguration)
            .Mappings(m =>
            {
                m.AutoMappings.Add(
                    AutoMap.AssemblyOf<EventDescriptor>(cfg)
                        .UseOverridesFromAssemblyOf<EventDescriptorMapping>());
            })
            .BuildSessionFactory();
    }

    [SetUp]
    public void SetUp()
    {
        _writeSession = CreateSessionFactory().OpenSession();
        _writeSession.BeginTransaction();
    }

    [Test]
    public void InsertAndReadTabOpened()
    {
        var objectToStoreInDbTemporarily = GetObjectToStoreInDbTemporarily();

        _writeSession.SaveOrUpdate(objectToStoreInDbTemporarily);
        _writeSession.Flush(); // the data needs to go to the database (even if only temporarily), rather than just staying in an NHibernate cache.

        var readSession = CreateSessionFactory(IsolationLevel.ReadUncommitted).OpenSession();
        var retrievedEventDescriptor = readSession.Get<EventDescriptor>(objectToStoreInDbTemporarily.Id); // this line throws the exception after 30 seconds.

        // If previous line worked, I could then assert inserted values match retrieved values at this point.
    }

    [TearDown]
    public void TearDown()
    {
        _writeSession.Transaction?.Rollback();
    }

    public class CustomAutomappingConfiguration : DefaultAutomappingConfiguration
    {
        public override bool ShouldMap(Type type)
        {
            return type.Name == typeof(EventDescriptor).Name; // we're only mapping this class for now.
        }
    }

为了简洁起见,我省略了创建对象的代码。最初的测试达到了它的目的——它迫使我必须正确定义所讨论对象的NHibernate映射。但是,最初的测试是在每次测试运行时插入新行,这让人感觉脏而且没有必要——因此采用了这种事务/回滚方法。