From 481f71bb3efd7735aa52eb7b6d7b96427bfdec82 Mon Sep 17 00:00:00 2001
From: Kristian Hellang <kh@novorender.com>
Date: Wed, 25 Sep 2024 12:28:40 +0200
Subject: [PATCH] Allow registering fully closed generic types, even if arity
 doesn't match #104

---
 src/Scrutor/ReflectionExtensions.cs |  5 +++++
 test/Scrutor.Tests/ScanningTests.cs | 13 +++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/Scrutor/ReflectionExtensions.cs b/src/Scrutor/ReflectionExtensions.cs
index a477df4..e8e41ed 100644
--- a/src/Scrutor/ReflectionExtensions.cs
+++ b/src/Scrutor/ReflectionExtensions.cs
@@ -234,6 +234,11 @@ public static bool HasMatchingGenericArity(this Type interfaceType, Type type)
         {
             if (interfaceType.IsGenericType)
             {
+                if (!interfaceType.ContainsGenericParameters)
+                {
+                    return true;
+                }
+
                 var argumentCount = interfaceType.GetGenericArguments().Length;
                 var parameterCount = type.GetGenericArguments().Length;
 
diff --git a/test/Scrutor.Tests/ScanningTests.cs b/test/Scrutor.Tests/ScanningTests.cs
index 46f2d7d..57b623f 100644
--- a/test/Scrutor.Tests/ScanningTests.cs
+++ b/test/Scrutor.Tests/ScanningTests.cs
@@ -220,6 +220,19 @@ public void CanRegisterGenericTypes()
             Assert.Equal(typeof(QueryHandler), service.ImplementationType);
         }
 
+        [Fact]
+        public void CanRegisterFullyClosedGenericWithDifferentArityThanServiceType()
+        {
+            Collection.Scan(scan => scan
+                .FromTypes(typeof(PartiallyClosedGeneric<string>))
+                .AsImplementedInterfaces()
+                .WithTransientLifetime());
+
+            var descriptor = Assert.Single(Collection);
+
+            Assert.Equal(typeof(IPartiallyClosedGeneric<string, int>), descriptor.ServiceType);
+        }
+
         [Fact]
         public void CanScanUsingAttributes()
         {