From a130074d4431fdd89639bfad5f2305bf2436a9c7 Mon Sep 17 00:00:00 2001
From: Oleksandr Tolstikov <Oleksandr.Tolstikov@selerant.com>
Date: Mon, 13 Sep 2021 23:25:49 +0300
Subject: [PATCH 1/2] - Fix isues #148 #117

---
 .../ServiceCollectionExtensions.Decoration.cs | 11 ++++-
 test/Scrutor.Tests/DecorationTests.cs         | 40 +++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/Scrutor/ServiceCollectionExtensions.Decoration.cs b/src/Scrutor/ServiceCollectionExtensions.Decoration.cs
index 9be40aee..8e27b0b9 100644
--- a/src/Scrutor/ServiceCollectionExtensions.Decoration.cs
+++ b/src/Scrutor/ServiceCollectionExtensions.Decoration.cs
@@ -341,9 +341,16 @@ private static object GetInstance(this IServiceProvider provider, ServiceDescrip
                 return descriptor.ImplementationInstance;
             }
 
-            if (descriptor.ImplementationType != null)
+            // Not suppose to be abstract. 
+            Type implementationType = descriptor.ImplementationType;
+            if (implementationType != null)
             {
-                return provider.GetServiceOrCreateInstance(descriptor.ImplementationType);
+                if (implementationType != descriptor.ServiceType)
+                    return provider.GetServiceOrCreateInstance(descriptor.ImplementationType);
+
+                // Since implementationType is equal to ServiceType we need explicitly create an implementation type through reflections in order to avoid infinite recursion.
+                // Should not cause issue with singletons, since singleton will be a decorator and after this fact we can don't care about lifecycle of decorable service (for sure, if IDisposable of decorator disposes underlying type:))
+                return provider.CreateInstance(implementationType);
             }
 
             return descriptor.ImplementationFactory(provider);
diff --git a/test/Scrutor.Tests/DecorationTests.cs b/test/Scrutor.Tests/DecorationTests.cs
index ed281ded..ff70d564 100644
--- a/test/Scrutor.Tests/DecorationTests.cs
+++ b/test/Scrutor.Tests/DecorationTests.cs
@@ -3,6 +3,7 @@
 using Microsoft.Extensions.DependencyInjection;
 using Xunit;
 using System.Linq;
+using static Scrutor.Tests.DecorationTests;
 
 namespace Scrutor.Tests
 {
@@ -217,8 +218,47 @@ public void DecoratingNonRegisteredServiceThrows()
             Assert.Throws<MissingTypeRegistrationException>(() => ConfigureProvider(services => services.Decorate<IDecoratedService, Decorator>()));
         }
 
+        [Fact]
+        public void Issue148_Decorate_IsAbleToDecorateConcreateTypes()
+        {
+            var sp = ConfigureProvider(sc =>
+            {
+                sc
+                    .AddTransient<IService, SomeRandomService>()
+                    .AddTransient<DecoratedService>()
+                    .Decorate<DecoratedService, Decorator2>();
+            });
+            
+            var result = sp.GetService<DecoratedService>() as Decorator2;
+            
+            Assert.NotNull(result);  
+            Assert.NotNull(result.Inner);
+            Assert.NotNull(result.Inner.Dependency);
+        }
+
         public interface IDecoratedService { }
 
+        public class DecoratedService
+        {
+            public DecoratedService(IService dependency)
+            {
+                Dependency = dependency;
+            }
+
+            public IService Dependency { get; }
+        }
+
+        public class Decorator2 : DecoratedService
+        {
+            public Decorator2(DecoratedService decoratedService)
+                : base(null)
+            {
+                Inner = decoratedService;
+            }
+
+            public DecoratedService Inner { get; }
+        }
+
         public interface IService { }
 
         private class SomeRandomService : IService { }

From d841d339efa480b2182c2c9f7e85dd651a213d70 Mon Sep 17 00:00:00 2001
From: Oleksandr Tolstikov <Oleksandr.Tolstikov@selerant.com>
Date: Tue, 14 Sep 2021 10:13:06 +0300
Subject: [PATCH 2/2] - cleanup

---
 src/Scrutor/ServiceCollectionExtensions.Decoration.cs | 2 +-
 test/Scrutor.Tests/DecorationTests.cs                 | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/Scrutor/ServiceCollectionExtensions.Decoration.cs b/src/Scrutor/ServiceCollectionExtensions.Decoration.cs
index 8e27b0b9..3716565f 100644
--- a/src/Scrutor/ServiceCollectionExtensions.Decoration.cs
+++ b/src/Scrutor/ServiceCollectionExtensions.Decoration.cs
@@ -346,7 +346,7 @@ private static object GetInstance(this IServiceProvider provider, ServiceDescrip
             if (implementationType != null)
             {
                 if (implementationType != descriptor.ServiceType)
-                    return provider.GetServiceOrCreateInstance(descriptor.ImplementationType);
+                    return provider.GetServiceOrCreateInstance(implementationType);
 
                 // Since implementationType is equal to ServiceType we need explicitly create an implementation type through reflections in order to avoid infinite recursion.
                 // Should not cause issue with singletons, since singleton will be a decorator and after this fact we can don't care about lifecycle of decorable service (for sure, if IDisposable of decorator disposes underlying type:))
diff --git a/test/Scrutor.Tests/DecorationTests.cs b/test/Scrutor.Tests/DecorationTests.cs
index ff70d564..e30b7242 100644
--- a/test/Scrutor.Tests/DecorationTests.cs
+++ b/test/Scrutor.Tests/DecorationTests.cs
@@ -3,7 +3,6 @@
 using Microsoft.Extensions.DependencyInjection;
 using Xunit;
 using System.Linq;
-using static Scrutor.Tests.DecorationTests;
 
 namespace Scrutor.Tests
 {