fixup! Implement a static IFieldInterceptorAccessor

Author: fredericDelaporte

src/NHibernate.Test/StaticProxyTest/StaticProxyFactoryFixture.cs

@@ -61,5 +61,34 @@ private static void VerifyGeneratedAssembly(System.Action assemblyGenerator)
 			new PeVerifier(assemblyName).AssertIsValid();
 		}
 #endif
+
+		public interface IPublicTest
+		{
+			int Id { get; }
+		}
+
+		public class PublicInterfaceTestClass : IPublicTest
+		{
+			public virtual int Id { get; set; }
+		}
+
+		[Test]
+		public void CanGenerateValidFieldInterceptorProxyWithAdditionalInterface()
+		{
+			var factory = new StaticProxyFactory();
+			factory.PostInstantiate(
+				typeof(TestClass).FullName,
+				typeof(TestClass),
+				// By way of the "proxy" attribute on the "class" mapping, an interface to use for the
+				// lazy entity load proxy instead of the persistentClass can be specified. This is "translated" into
+				// having an additional interface in the interface list, instead of just having INHibernateProxy.
+				// (Quite a loosy semantic...)
+				// The field interceptor proxy ignores this setting, as it does not delegate its implementation
+				// to an instance of the persistentClass, and so cannot implement interface methods.
+				new HashSet<System.Type> {typeof(INHibernateProxy), typeof(IPublicTest)},
+				null, null, null);
+			var fieldProxy = factory.GetFieldInterceptionProxy(null);
+			Assert.That(fieldProxy, Is.InstanceOf<TestClass>());
+		}
 	}
 }

src/NHibernate/Proxy/FieldInterceptorProxyBuilder.cs

@@ -47,8 +47,9 @@ public static TypeInfo CreateProxyType(System.Type baseType)
 			var parentType = baseType;
 			if (baseType.IsInterface)
 			{
-				parentType = typeof(object);
-				interfaces.Add(baseType);
+				throw new ArgumentException(
+					$"Field interceptor proxy does not support being build on an interface baseType ({baseType.FullName}).",
+					nameof(baseType));
 			}
 
 			interfaces.RemoveWhere(i => !i.IsVisible);

src/NHibernate/Proxy/StaticProxyFactory.cs

@@ -44,7 +44,7 @@ private Func<ILazyInitializer, NHibernateProxyFactoryInfo, INHibernateProxy> Cre
 
 		public override object GetFieldInterceptionProxy(object instanceToWrap)
 		{
-			var cacheEntry = new ProxyCacheEntry(IsClassProxy ? PersistentClass : typeof(object), System.Type.EmptyTypes);
+			var cacheEntry = new ProxyCacheEntry(PersistentClass, System.Type.EmptyTypes);
 			var proxyActivator = FieldInterceptorCache.GetOrAdd(cacheEntry, CreateFieldInterceptionProxyActivator);
 			return proxyActivator();
 		}