Spec test for public-no-arg generic constraint fails

See https://github.com/aspnet/Extensions/pull/536/commits/66a64ba8fcd7d90b395f8a0af45d2a0b04be4b42#diff-e37d6761fa5732546952f42a605c42ebR14

I’m adding support for constrained open generics to the base DI package. This package fails one of the spec tests added for public no-arg constraints. I’ve verified that resolving in the base package does work:

public class NewConstrained<T> : ISingleGeneric<T>
    where T : new()
{
}

public class ClassWithNew
{
}

[Fact]
public void CanResolveMultipleServicesWhenConstrainedWithNewConstraint()
{
    var builder = new ContainerBuilder();

    builder.RegisterGeneric(typeof(NewConstrained<>)).As(typeof(ISingleGeneric<>));
    builder.RegisterGeneric(typeof(CGeneric<>)).As(typeof(ISingleGeneric<>));

    var container = builder.Build();

    Assert.Equal(2, container.Resolve<IEnumerable<ISingleGeneric<ClassWithNew>>>().Count());
    Assert.Single(container.Resolve<IEnumerable<ISingleGeneric<string>>>());
}

That test passes in Autofac. However, this new spec test fails:

[Fact]
public void PublicNoArgCtorConstrainedOpenGenericServicesCanBeResolved()
{
    // Arrange
    var collection = new TestServiceCollection();
    collection.AddTransient(typeof(IFakeOpenGenericService<>), typeof(ClassWithNoConstraints<>));
    collection.AddTransient(typeof(IFakeOpenGenericService<>), typeof(ClassWithNewConstraint<>));
    var provider = CreateServiceProvider(collection);
    // Act
    var allServices = provider.GetServices<IFakeOpenGenericService<PocoClass>>().ToList();
    var constrainedServices = provider.GetServices<IFakeOpenGenericService<ClassWithPrivateCtor>>().ToList();
    // Assert
    Assert.Equal(2, allServices.Count);
    Assert.Equal(1, constrainedServices.Count);
}

Stack trace:

[xUnit.net 00:00:01.36]     Autofac.Extensions.DependencyInjection.Test.SpecificationTests.PublicNoArgCtorConstrainedOpenGenericServicesCanBeResolved [FAIL]
Failed   Autofac.Extensions.DependencyInjection.Test.SpecificationTests.PublicNoArgCtorConstrainedOpenGenericServicesCanBeResolved
Error Message:
 Autofac.Core.DependencyResolutionException : An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = IFakeOpenGenericService`1[] (DelegateActivator), Services = [System.Collections.Generic.IEnumerable`1[[Microsoft.Extensions.DependencyInjection.Specification.Fakes.IFakeOpenGenericService`1[[Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithPrivateCtor, Microsoft.Extensions.DependencyInjection.Specification.Tests, Version=3.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60]], Microsoft.Extensions.DependencyInjection.Specification.Tests, Version=3.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60]]], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = ExternallyOwned ---> GenericArguments[0], 'Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithPrivateCtor', on 'Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithNewConstraint`1[T]' violates the constraint of type 'T'. (See inner exception for details.)
---- System.ArgumentException : GenericArguments[0], 'Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithPrivateCtor', on 'Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithNewConstraint`1[T]' violates the constraint of type 'T'.
-------- System.TypeLoadException : GenericArguments[0], 'Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithPrivateCtor', on 'Microsoft.Extensions.DependencyInjection.Specification.Fakes.ClassWithNewConstraint`1[T]' violates the constraint of type parameter 'T'.
Stack Trace:
   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.Execute()
   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)
   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)
   at Autofac.ResolutionExtensions.TryResolveService(IComponentContext context, Service service, IEnumerable`1 parameters, Object& instance)
   at Autofac.ResolutionExtensions.ResolveService(IComponentContext context, Service service, IEnumerable`1 parameters)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider) in C:\dev\aspnet-extensions\src\DependencyInjection\DI.Abstractions\src\ServiceProviderServiceExtensions.cs:line 79
   at Microsoft.Extensions.DependencyInjection.Specification.DependencyInjectionSpecificationTests.PublicNoArgCtorConstrainedOpenGenericServicesCanBeResolved() in C:\dev\aspnet-extensions\src\DependencyInjection\DI.Specification.Tests\src\DependencyInjectionSpecificationTests.cs:line 615
----- Inner Stack Trace -----
   at System.RuntimeType.ValidateGenericArguments(MemberInfo definition, RuntimeType[] genericArguments, Exception e)
   at System.RuntimeType.MakeGenericType(Type[] instantiation)
   at Autofac.Features.OpenGenerics.OpenGenericServiceBinder.TryBindServiceType(Service service, IEnumerable`1 configuredOpenGenericServices, Type openGenericImplementationType, Type& constructedImplementationType, IEnumerable`1& constructedServices)
   at Autofac.Features.OpenGenerics.OpenGenericRegistrationSource.<RegistrationsFor>d__3.MoveNext()
   at Autofac.Core.Registration.ComponentRegistry.GetInitializedServiceInfo(Service service)
   at Autofac.Core.Registration.ComponentRegistry.RegistrationsFor(Service service)
   at Autofac.Features.Collections.CollectionRegistrationSource.<>c__DisplayClass0_0.<RegistrationsFor>b__0(IComponentContext c, IEnumerable`1 p)
   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)
   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)
----- Inner Stack Trace -----
   at System.RuntimeTypeHandle.Instantiate(RuntimeTypeHandle handle, IntPtr* pInst, Int32 numGenericArgs, ObjectHandleOnStack type)
   at System.RuntimeTypeHandle.Instantiate(Type[] inst)
   at System.RuntimeType.MakeGenericType(Type[] instantiation)

My PR isn’t merged, so this is contingent on my PR getting merged. If you fix this behavior, you’ll want to open a PR with the MS DI package to remove that part about skipping this test.

[tillig]

I don’t think there’s any action to take here. We can probably just close it. I don’t believe we have any intention of implementing the behavior here.

[alsami]

Circling back from the PR, it appears this may be added to the base/default container but not added to the spec.

Should we move this issue to the autofac repository then?