AutoFixture无法创建索赔(使用.NET Framework4.6)

Question

我刚刚安装了VS2015，同时安装了.NET Framework4.6，突然之间，AutoFixture 3.30.8无法创建Claim对象。我猜新的.NET框架版本4.6在AutoFixture中引起了一些问题。

我创建了一个测试项目(针对.NET框架4.5.1)，其中包含VS2013中的以下代码：

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);
        }
    }
}

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

在安装VS2015之前，使用这种方法创建用于工作的Claim对象。实际上，我把这个解决方案发送给了我的同事，他只安装了VS2013，并且对他有效。

我注意到F12-导航到Claim代码显示了来自4.5.1DLL的元数据。VS2015安装程序搞砸了4.5.1DLL有问题吗？或者这可能是安装4.6的AutoFixture中发现的一个bug？

我将我机器上的DotPeek输出与同事的System.Security.Claims.Claim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

我的照片显示：

// Assembly location: C:\Windows\Microsoft.NET\Framework\v4.0.30319\mscorlib.dll

His有5个构造函数，分别采用strings或ClaimsIdentity。

new有7个构造函数，其中包括两个新构造函数，如下所示：

public Claim(BinaryReader reader) { ... }

和

public Claim(BinaryReader reader, ClaimsIdentity subject) { ... }

我想解决这个问题的方法是强制AutoFixture使用特定的构造函数。但这一巨大的变化已经从微软的网络中溜走，这确实让我感到紧张。还有其他像这样的变化吗？

Answer 1

作为使AutoFixture像以前一样工作的一种解决方法，我定制了它创建Claim的方式，以选择参数最多的构造函数。

fixture.Customize<System.Security.Claims.Claim>(
    c => c.FromFactory(new MethodInvoker(new GreedyConstructorQuery())));

造成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，两个新的构造函数采用一个BinaryReader参数，该参数依赖于AutoFixture不能构造的Stream。幸运的是，AutoFixture是好的和可配置的:)

正如上面所提到的，这确实让我感到紧张，因为微软的网络已经渗透了这一巨大的变化。另外，如果他们决定在Framework4.7中添加另一个构造函数，其中包含20个参数(包括一个BinaryReader )，那么我们将再次陷入困境。