EntityFramework，DbContextScope和Effort - 異常：DbContext已被置於單元測試中

我正在嘗試為服務層編寫單元測試（使用NUnit），該服務層使用：

1. 實體框架作為數據訪問層
2. DbContextScope管理的DbContext一生

我還使用Effort.EF6在單元測試中模擬DbContext。不幸的是，我找不到讓DbContextScope與Effort兼容的方法，以便我可以正確測試所有案例。

代碼概述

服務層由執行某些業務邏輯的類（服務）組成。每個方法都被視為一個完整的事務，以context.SaveChanges()結束。例：

    private IDbContextScopeFactory _dbContextScopeFactory;

    public DepartmentsService(IDbContextScopeFactory dbContextScopeFactory)
    {
        _dbContextScopeFactory = dbContextScopeFactory;
    }

    public BusinessModel.Department Insert(BusinessModel.Department department)
    {
        using (var dbContextScope = _dbContextScopeFactory.Create())
        {
            // Validation
            ValidateAndThrowOnFailure(department, new DepartmentAddValidator());

            // Operation
            DBModel.Department newDepartment = Mapper.Map<DBModel.Department>(department);

            newDepartment.InsertDateUTC = DateTime.UtcNow;

            dbContextScope.DbContexts.Get<DPSContext>().Departments.Add(newDepartment);
            dbContextScope.SaveChanges();

            return Mapper.Map<BusinessModel.Department>(newDepartment);
        }
    }

為了對這種方法進行單元測試，我在每次測試前做了一些準備：

    private IDepartmentsService _departmentsService;
    private IDbContextScopeFactory _dbContextScopeFactory;
    private IDbContextFactory _dbContextFactory;
    private DBModel.DPSContext _dbEntities;

    [SetUp]
    public void ReInitializeTest()
    {
        // Setup DbContext with Effort.EF6
        string connStr = ConfigurationManager.ConnectionStrings["DPSContext"].ConnectionString;
        DbConnection connection = EntityConnectionFactory.CreateTransient(connStr);
        _dbEntities = new DBModel.DPSContext(connection);

        // Fill DbContext with in-memory data
        _dbEntities.Departments.AddRange(DataInitializer.GetDepartments());
        _dbEntities.SaveChanges();

        // Mock IDbContextFactory so that it returns in-memory context
        var contextFactoryMock = new Mock<IDbContextFactory>();

        contextFactoryMock
            .Setup(f => f.CreateDbContext<DBModel.DPSContext>())
            .Returns(_dbEntities);

        _dbContextFactory = contextFactoryMock.Object;

        // Setup DbContextScopeFactory to use mocked context
        _dbContextScopeFactory = new DbContextScopeFactory(_dbContextFactory);
        _departmentsService = new DepartmentsService(_dbContextScopeFactory);
    }

測試和問題

這是一個簡單的單元測試：

    [Test]
    public void Insert_WhenValidModelPassed_ShouldInsertNewRecord()
    {
        // Given
        BusinessModel.Department newDepartment = DataInitializer.GetExampleOfNewDepartment();

        // When
        _departmentsService.Insert(newDepartment);

        // Then
        Assert.AreEqual(3, _dbEntities.Departments.Count());
    }

問題是測試失敗，但有異常：

System.InvalidOperationException : The operation cannot be completed because the DbContext has been disposed.

似乎在Insert方法內部使用的DbContextScope內部在using塊的末尾處理分配的上下文，因此Assert在調用時拋出異常。有沒有人遇到類似的問題，或者只是知道我應該做些什麼來成功測試這個和類似的場景？