那些遇到过的问题

AutoFixture 无法创建 Claim（使用 .NET Framework 4.6）

dem*_*key 5 c# autofixture visual-studio-2015 .net-4.6

我刚刚安装了VS2015，同时安装了.NET Framework 4.6，突然AutoFixture 3.30.8无法创建Claim对象。我猜新的 .NET Framework 4.6 版会导致 AutoFixture 出现一些问题。

我在 VS2013 中创建了一个包含以下代码的测试项目（针对 .NET Framework 4.5.1）：

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Ploeh.AutoFixture;

namespace AutoFixtureTester
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void CanCreateClaim()
        {
            var fixture = new Fixture();
            fixture.Behaviors.Add(new OmitOnRecursionBehavior());

            var claim = fixture.Create<System.Security.Claims.Claim>(); // exception here

            Assert.IsNotNull(claim);
        }
    }
}
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错误如下：

Ploeh.AutoFixture.ObjectCreationException: AutoFixture was unable to create an instance from System.IO.Stream, most likely because it has no public constructor, is an abstract or non-public type.

Request path:
         System.Security.Claims.Claim --> 
          System.IO.BinaryReader reader --> 
           System.IO.BinaryReader --> 
            System.IO.Stream input --> 
             System.IO.Stream
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.SeedIgnoringRelay.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.ParameterRequestRelay.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.MethodInvoker.<>c__DisplayClass2.<Create>b__0(ParameterInfo pi)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Ploeh.AutoFixture.Kernel.MethodInvoker.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.SeedIgnoringRelay.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.ParameterRequestRelay.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.MethodInvoker.<>c__DisplayClass2.<Create>b__0(ParameterInfo pi)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Ploeh.AutoFixture.Kernel.MethodInvoker.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.Kernel.SeedIgnoringRelay.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.AutoPropertiesTarget.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.Postprocessor`1.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TracingBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.TerminatingWithPathSpecimenBuilder.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.BehaviorRoot.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Fixture.Create(Object request, ISpecimenContext context)
   at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request)
   at Ploeh.AutoFixture.SpecimenFactory.Create[T](ISpecimenContext context, T seed)
   at Ploeh.AutoFixture.SpecimenFactory.Create[T](ISpecimenContext context)
   at Ploeh.AutoFixture.SpecimenFactory.Create[T](ISpecimenBuilder builder)
   at AutoFixtureTester.UnitTest1.CanCreateClaim() in D:\Sandbox\AutoFixtureTester\AutoFixtureTester\UnitTest1.cs:line 16
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在安装 VS2015 之前，这种创建Claim对象的方式曾经起作用。实际上，我将此解决方案发送给了我只安装了 VS2013 的同事，并且对他有用。

我注意到 F12 导航到Claim代码显示来自 4.5.1 DLL 的元数据。VS2015 安装程序搞砸了 4.5.1 DLL 是否存在问题？或者这可能是安装 4.6 后发现的 AutoFixture 中的一个错误？

我将System.Security.Claims.Claim我的机器的DotPeek 输出与我同事的输出进行了比较。他的节目：

// Assembly location: C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5.1\mscorlib.dll
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我的显示：

// Assembly location: C:\Windows\Microsoft.NET\Framework\v4.0.30319\mscorlib.dll
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他有 5 个构造函数采用strings 或ClaimsIdentity。
我的有 7 个构造函数，包括 2 个看起来像这样的新构造函数：

public Claim(BinaryReader reader) { ... }
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和

public Claim(BinaryReader reader, ClaimsIdentity subject) { ... }
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我想这种情况的解决方法是以某种方式强制 AutoFixture 使用特定的构造函数。但让我感到紧张的是，这个突破性的变化已经从微软的网络中溜走了。还有其他类似的变化吗？

dem*_*key 5

作为让 AutoFixture 像以前一样工作的解决方法，我自定义了它的创建方式，Claim以选择具有最多参数的构造函数。

fixture.Customize<System.Security.Claims.Claim>(
    c => c.FromFactory(new MethodInvoker(new GreedyConstructorQuery())));
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此问题的原因似乎是安装 4.6 影响了 4.5.1 DLL。Claim现在有 7 个构造函数，2 个新的构造函数接受一个BinaryReader参数，该参数取决于StreamAutoFixture 不能构造的参数。幸运的是，AutoFixture 很好且可配置:)

如上所述，这一重大变化已经从微软的网络中溜走，这确实让我感到紧张。另外让我担心的是，如果他们决定在未来向 Framework 4.7 添加另一个构造函数，使用 20 个参数，包括 a BinaryReader，那么我们将再次陷入困境。

  • 我确信微软并不认为这是一个重大变化。之前使用 `claim` 的普通代码会像以前一样继续编译和工作；向类添加新成员并不构成重大更改。AutoFixture 中断的原因是因为它从不*知道*如何创建 `Claim` 实例。除了少数著名的 BCL 类型外，AutoFixture 不*知道*如何创建各种类型的对象，而是使用**尽力而为启发式**来创建对象。当框架发生变化时，偶尔会出现这样的问题；有时，它可能会走另一条路。 (2认同)

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