AutoFixture 在复杂对象中创建不需要的深度

Question

我有一个来自 EF6（数据库优先）的复杂图表，我想在测试我的域模型时使用模拟和测试装置进行模拟。为了防止循环依赖的问题，我在测试设置中添加了这些行：

private Fixture _fixture;
public WhenRetrievingPlans()
{
    _fixture = new Fixture();
    _fixture.Behaviors.OfType<ThrowingRecursionBehavior>().ToList()
                            .ForEach(b => _fixture.Behaviors.Remove(b)); 
    _fixture.Behaviors.Add(new OmitOnRecursionBehavior());
    using (var writer = new StreamWriter(@"D:\Workspace\Project\source\Project.Model.Test\trace.txt"))
    {
        _fixture.Behaviors.Add(new TracingBehavior(writer));

然后我试图阻止夹具试图将对象图追逐到遗忘，并创建一个没有任何子对象的简单对象，如下所示：

        _fixture.Build<EntityType>()
            .Without(e => e.ObjectProperty1)
            .Without(e => e.ObjectProperty2)
            .Without(e => e.CollectionProperty3)
            .Without(e => e.CollectionProperty4)
            .Without(e => e.ObjectProperty5)
            ...
            .Create();

这样就不会创建属于此 EntityType 属性的对象或集合。其余属性为简单类型，包括一些 Nullable 和 DateTime 值以及 Int32 和 String 类型。

我想让 AutoFixture 创建一个 EntityType 实例，然后我打算从 Mock 中返回它。 （这可能不相关。）

        var entitiesDbSetMock = new Mock<IDbSet<EntityType>>();
        entitiesDbSetMock.SetupAllProperties();
        _fixture.Inject<IDbSet<EntityType>>(entitiesDbSetMock.Object);

然后我将对象添加到这个 Mock 中：

        var entity = _fixture.Create<EntityType>();
        entitiesDbSetMock.Object.Attach(entity);

问题是这样的：AutoFixture 并没有阻止自己生成可以从此 EntityType 访问的所有可能对象，即使我使用了所有 .Without() 操作。我怎么知道？因为我打开了追踪。仅仅为了这一次 Create 操作，就产生了将近 750,000 行的 trace（它是一个 100MB 的文件）。

在阅读跟踪时，第一部分显示了 EntityType 的创建以及我没有排除的所有属性的设置。但是在那个东西被创建之后，它似乎又被创建了，但这一次它忽略了我的Without()自定义，并且深入。

Requested: Ploeh.AutoFixture.Kernel.SeededRequest
  Requested: Project.Data.EntityType
    Requested: Int32 EntityTypeID
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.Int32
        Created: 232
      Created: 232
    Created: 232
    Requested: System.Nullable`1[System.Int32] ForeignKey1ID
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.Nullable`1[System.Int32]
          Requested: Int32 value
            Requested: Ploeh.AutoFixture.Kernel.SeededRequest
              Requested: System.Int32
              Created: 224
            Created: 224
          Created: 224
        Created: 224
      Created: 224
    Created: 224
    Requested: Int32 Property2ID
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.Int32
        Created: 40
      Created: 40
    Created: 40
    Requested: System.DateTime Property3Date
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.DateTime
        Created: 6/6/2014 4:05:24 PM
      Created: 6/6/2014 4:05:24 PM
    Created: 6/6/2014 4:05:24 PM
    *... (similar lines elided for brevity)*
    Requested: Project.Data.OtherEntity OtherEntity
    Created: Ploeh.AutoFixture.Kernel.OmitSpecimen
    Requested: Project.Data.YetAnotherEntity YetAnotherEntity
    Created: Ploeh.AutoFixture.Kernel.OmitSpecimen
    Requested: System.Collections.Generic.ICollection`1[Project.Data.CollectionEntity] CollectionEntities
    Created: Ploeh.AutoFixture.Kernel.OmitSpecimen
    *... (similar lines elided for brevity)*
  Created: Project.Data.EntityType
Created: Project.Data.EntityType

就在那里，我希望跟踪完成。该对象已创建，正是我想要的。但它并不止于此。紧接着，我看到 AutoFixture 继续运行。

Requested: Ploeh.AutoFixture.Kernel.SeededRequest
  Requested: Project.Data.YetAnotherEntity
  Created: Project.Data.YetAnotherEntity
Created: Project.Data.YetAnotherEntity
Requested: Ploeh.AutoFixture.Kernel.SeededRequest
  Requested: Project.Data.UnrelatedEntity
  Created: Project.Data.UnrelatedEntity
Created: Project.Data.UnrelatedEntity
Requested: Ploeh.AutoFixture.Kernel.SeededRequest
  Requested: Project.Data.EntityType  *<<-- Again? We did this already.*
    Requested: Int32 EntityTypeID
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.Int32
        Created: 107
      Created: 107
    Created: 107
    Requested: System.Nullable`1[System.Int32] ForeignKey1ID
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.Nullable`1[System.Int32]
          Requested: Int32 value
            Requested: Ploeh.AutoFixture.Kernel.SeededRequest
              Requested: System.Int32
              Created: 87
            Created: 87
          Created: 87
        Created: 87
      Created: 87
    Created: 87
    Requested: Int32 Property2ID
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.Int32
        Created: 105
      Created: 105
    Created: 105
    Requested: System.DateTime Property3Date
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: System.DateTime
        Created: 5/31/2014 6:50:10 PM
      Created: 5/31/2014 6:50:10 PM
    Created: 5/31/2014 6:50:10 PM
    Requested: Project.Data.OtherEntity OtherEntity  *<<!! NO! I stopped you!*
      Requested: Ploeh.AutoFixture.Kernel.SeededRequest
        Requested: Project.Data.OtherEntity
          Requested: Int32 ForeignKey1ID
            Requested: Ploeh.AutoFixture.Kernel.SeededRequest
              Requested: System.Int32
              Created: 168
            Created: 168
          Created: 168
          Requested: System.String Name
            Requested: Ploeh.AutoFixture.Kernel.SeededRequest
              Requested: System.String
              Created: 61eb26e3-890d-4d0d-badd-cd3467c299ed
            Created: Name61eb26e3-890d-4d0d-badd-cd3467c299ed
          Created: Name61eb26e3-890d-4d0d-badd-cd3467c299ed
          Requested: Int32 OtherEntityID
            Requested: Ploeh.AutoFixture.Kernel.SeededRequest
              Requested: System.Int32
              Created: 187
            Created: 187
          Created: 187
*... and on and on for 750,000 more lines.

当然，这东西可能有各种各样的代码味道，而且我知道 Mark Seemann 在 EF 或任何其他 ORM 上并不大。但我认为它应该可以工作，而且我无法弄清楚我错过了什么。

Answer 1

现在我更仔细地查看示例以回答 Mark 的评论（谢谢你，Mark！！）...我看到 Build 有一个 T 类型的返回值方法。 （拍了拍额头）。

所以现在我发现我认为 Build 所做的事情是错误的。它实际上在那里实例化了一个 T 。我怀疑我需要做的（创建模板）是扩展 SpecimenBuilder 并以某种方式注册它，方法是将其添加到设置夹具的自定义/自定义序列中。

马克，如果你想留下更好的答案，我会等一两天，然后选择你的答案作为正确答案。

Answer 2

尝试使用 RepeatCount 属性

var objFixture = new Fixture();

objFixture.RepeatCount = 0;