Castle.DynamicProxy.ProxyGenerationException: Duplicate element: Castle.DynamicProxy.Generators.MetaMethod

[TheReaLee]

Same class names, in different projects both implementing the same interface with different namespaces. When using Mock.Object, the exception is thrown.

Castle.Core: 4.4.1
Moq: 4.16.1
.NETFramework: 4.7.2

TestClass

public class ReportInstanceBackwardCompatibilityTests
{
    private readonly ReportInstanceRepositoryIntegrationTestsFixture _fixture;

    public ReportInstanceBackwardCompatibilityTests(ReportInstanceRepositoryIntegrationTestsFixture fixture)
    {
        this._fixture = fixture;
        this._fixture.ConfigureDataStores(new MyDataStoreCollection())
    }

    [Fact]

    public void Test1()
    {
        /* On run of this test, the error should generate */
    }
}

MyDataStoreCollection

public class MyDataStoreCollection: IDataStoreCollection
{
    protected readonly Mock<IValidator<It.IsAnyType>> ValidatorMock;

    public MyDataStoreCollection()
    {
	this.ValidatorMock = new Mock<IValidator<It.IsAnyType>>();
    }

    public void RegisterValidator<TEntity>() 
    	where TEntity: new()
    {            
        this.ValidatorMock.As<IValidator<TEntity>>().Setup(x => x.Validate(It.IsAny<TEntity>(), It.IsAny<System.ComponentModel.DataAnnotations.ValidationContext>())).Returns(new ValidationResults());
    }

    /* Exception on .Returns(this.ValidatorMock.Object); */
    public IValidatorFactory GetValidatorFactory()
    {
	Mock<IValidatorFactory> validatorFactoryMock = new Mock<IValidatorFactory>();            
	validatorFactoryMock.Setup(x => x.CreateValidator<It.IsAnyType>(It.IsAny<IUnitOfWork>())).Returns(this.ValidatorMock.Object);

	return validatorFactoryMock.Object;
    }
}

TestFixture

public class MyFixture
{
    public void ConfigureDataStores(IDataStoreCollection dataStoreCollection)
    {
    	/* ReportingSchema.Reporting.Database.Model.ReportInstance is contained in project named 'Reporting'
	 * ReportInstance is contained in project named 'ReportingTenant'
	 * both implementing same interface
    	 */
        dataStoreCollection.RegisterValidator<ReportingSchema.Reporting.Database.Model.ReportInstance>();
        dataStoreCollection.RegisterValidator<ReportInstance>();     
        
        /* Exception when calling this method... */
        dataStoreCollection.GetValidatorFactory();
    }
}

IValidatorFactory

public interface IValidatorFactory
{
    IValidator<TModel> CreateValidator<TModel>(IUnitOfWork uow);
    IValidator<TModel> CreateValidator<TModel>();
    IValidator CreateValidator(Type modelType);
}

IValidator

public interface IValidator<TModel>
{    
    ValidationResults Validate(TModel instance);
}

ValidationResults taken from Nuget Microsoft.Practices.EnterpriseLibrary.Validation

IDataStoreCollection

public interface IDataStoreCollection
{   
    void RegisterDataStore<TEntity>() where TEntity : new();
  
    void RegisterDataStore<TEntity, TDataStore>()
        where TEntity : new()
        where TDataStore : IDataStore<TEntity>;
        
    IValidatorFactory GetValidatorFactory();
}

IDataStore

public interface IDataStore<TEntity>
{
    TEntity Insert(TEntity pModel);
}

IReportInstance

public interface IReportInstance
{       
	Guid Id { get; set; }
}

ReportingSchema ReportInstance (In project Reporting.csproj)

[Entity(Schema = "Reporting", Name = "Report_Instance", TableName = "Report_Instance")]
[EntitySecurity(ImplementsRecordSecurity = true)]
public class ReportInstance : IReportInstance
{
    [Key]
    [Index(IsUnique = true)]
    [Column(Order = 1)]
    public Guid Id {get;set;}
}

ReportingTenant schema ReportInstance (IN project ReportingTenant.csproj

[Entity(Schema = "ReportingTenant", Name = "Report_Instance", TableName = "Report_Instance")]
[EntitySecurity(ImplementsRecordSecurity = true)]
public class ReportInstance :  IReportInstance
{
    [Key]
    [Index(IsUnique = true)]
    [Column(Order = 1)]
    public Guid Id {get;set;}
}

IUnitOfWork

public interface IUnitOfWork
{
    IDataContext GetDataContext(Type type);      
}

IDataContext

public interface IDataContext : IDisposable
{
    bool InTransaction { get; }
    Task<int> CommitAsync();
}

Stack Trace

   at Castle.DynamicProxy.Generators.TypeElementCollection`1.Add(TElement item)
   at Castle.DynamicProxy.Contributors.CompositeTypeContributor.CollectElementsToProxy(IProxyGenerationHook hook, MetaType model)
   at Castle.DynamicProxy.Generators.InterfaceProxyWithoutTargetGenerator.GenerateType(String typeName, Type proxyTargetType, Type[] interfaces, INamingScope namingScope)
   at Castle.DynamicProxy.Generators.InterfaceProxyWithTargetGenerator.<>c__DisplayClass6_0.<GenerateCode>b__0(String n, INamingScope s)
   at Castle.DynamicProxy.Generators.BaseProxyGenerator.<>c__DisplayClass34_0.<ObtainProxyType>b__0(CacheKey _)
   at Castle.Core.Internal.SynchronizedDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Castle.DynamicProxy.Generators.BaseProxyGenerator.ObtainProxyType(CacheKey cacheKey, Func`3 factory)
   at Castle.DynamicProxy.Generators.InterfaceProxyWithTargetGenerator.GenerateCode(Type proxyTargetType, Type[] interfaces, ProxyGenerationOptions options)
   at Castle.DynamicProxy.DefaultProxyBuilder.CreateInterfaceProxyTypeWithoutTarget(Type interfaceToProxy, Type[] additionalInterfacesToProxy, ProxyGenerationOptions options)
   at Castle.DynamicProxy.ProxyGenerator.CreateInterfaceProxyWithoutTarget(Type interfaceToProxy, Type[] additionalInterfacesToProxy, ProxyGenerationOptions options, IInterceptor[] interceptors)
   at Moq.CastleProxyFactory.CreateProxy(Type mockType, IInterceptor interceptor, Type[] interfaces, Object[] arguments) in C:\projects\moq4\src\Moq\ProxyFactories\CastleProxyFactory.cs:line 50
   at Moq.Mock`1.InitializeInstance() in C:\projects\moq4\src\Moq\Mock`1.cs:line 309
   at Moq.Mock`1.OnGetObject() in C:\projects\moq4\src\Moq\Mock`1.cs:line 325
   at Moq.Mock`1.get_Object() in C:\projects\moq4\src\Moq\Mock`1.cs:line 283

[stakx]

Hi @TheReaLee (sorry, I accidentally hit the Close issue button), could you please provide a full repro, i.e. not just the code where the exception is reported, but also include the declarations for the referenced types. Thanks!

[TheReaLee]

Updated @stakx, let me know if you require more information

[stakx]

Sorry @TheReaLee, I cannot piece together repro code that compiles without error.

• Some of the types you're referencing are missing: e.g. IValidator and ReportInstanceRepositoryIntegrationTestsFixture.
• You're referencing custom attributes from some unspecified namespace or NuGet package: e.g. [Entity], [EntitySchema], [Key], [Index], and [Column].
• There is at least one obvious Moq usage error: Mock<IValidator<It.IsAnyType>>. It.IsAnyType can only act as a type placeholder inside setup or verification expressions. It doesn't make any sense to use it outside of those expressions. (Because your own class and interface types aren't subtypes of It.IsAnyType – at least they shouldn't be! – there will not ever be any object at runtime that is assignment-compatible with It.IsAnyType, so your IValidator<It.IsAnyType> won't ever receive any It.IsAnyType-typed object to validate. Such a validator (whether mocked or not) is therefore completely useless in practice. Mock<IValidator<object>> would seem to make more sense.)

Could you perhaps provide a downloadable & compilable Visual Studio solution that doesn't need any further puzzle action on our part? :-)

[stakx]

I've re-tried producing the reported error using a variety of type proxying constellations, without any success. Closing this older issue as not reproducible.