Fix interception for private protected methods

CHANGELOG.md

@@ -6,6 +6,7 @@ Enhancements:
 - .NET Standard 2.0 and 2.1 support (@lg2de, #485)
 
 Bugfixes:
+- `private protected` methods are not intercepted (@CrispyDrone, #535)
 - `System.UIntPtr` unsupported (@stakx, #546)
 
 Deprecations:

src/Castle.Core.Tests/DynamicProxy.Tests/AccessLevelTestCase.cs

@@ -14,6 +14,7 @@
 
 namespace Castle.DynamicProxy.Tests
 {
+	using System;
 	using System.Collections.Generic;
 	using System.Reflection;
 
@@ -85,5 +86,50 @@ public void InternalConstructorIsReplicatedWhenInternalsVisibleTo()
 			object proxy = generator.CreateClassProxy(typeof(InternalClass), new StandardInterceptor());
 			Assert.IsNotNull(proxy.GetType().GetConstructor(new[] { typeof(IInterceptor[]) }));
 		}
+
+		[TestCase(typeof(InternalMethodClass))]
+		[TestCase(typeof(PrivateProtectedMethodClass))]
+		[TestCase(typeof(ProtectedMethodClass))]
+		[TestCase(typeof(ProtectedInternalMethodClass))]
+		public void Methods_made_visible_by_InternalsVisibleTo_can_be_intercepted(Type methodClass)
+		{
+			var method = methodClass.GetMethod("Method", BindingFlags.NonPublic | BindingFlags.Instance);
+			Assume.That(ProxyUtil.IsAccessible(method));  // because this assembly makes its internals visible to DynamicProxy
+
+			var realObj = (IMethodClass)Activator.CreateInstance(methodClass);
+			Assert.Throws<Exception>(realObj.InvokeMethod);
+
+			var proxy = (IMethodClass)generator.CreateClassProxy(methodClass, new DoNothingInterceptor());
+			Assert.DoesNotThrow(proxy.InvokeMethod);
+		}
+
+		private interface IMethodClass
+		{
+			void InvokeMethod();
+		}
+
+		public class InternalMethodClass : IMethodClass
+		{
+			public void InvokeMethod() => Method();
+			internal virtual void Method() => throw new Exception();
+		}
+
+		public class PrivateProtectedMethodClass : IMethodClass
+		{
+			public void InvokeMethod() => Method();
+			private protected virtual void Method() => throw new Exception();
+		}
+
+		public class ProtectedMethodClass : IMethodClass
+		{
+			public void InvokeMethod() => Method();
+			protected virtual void Method() => throw new Exception();
+		}
+
+		public class ProtectedInternalMethodClass : IMethodClass
+		{
+			public void InvokeMethod() => Method();
+			protected internal virtual void Method() => throw new Exception();
+		}
 	}
 }

src/Castle.Core/DynamicProxy/Contributors/MembersCollector.cs

@@ -223,7 +223,7 @@ protected bool AcceptMethod(MethodInfo method, bool onlyVirtuals, IProxyGenerati
 			}
 
 			//can only proxy methods that are public or protected (or internals that have already been checked above)
-			if ((method.IsPublic || method.IsFamily || method.IsAssembly || method.IsFamilyOrAssembly) == false)
+			if ((method.IsPublic || method.IsFamily || method.IsAssembly || method.IsFamilyOrAssembly || method.IsFamilyAndAssembly) == false)
 			{
 				return false;
 			}