From 75f2cc93163e475863a5280641b337340663a813 Mon Sep 17 00:00:00 2001
From: Simon Gockner <simon.gockner@gmail.com>
Date: Wed, 13 Nov 2019 16:12:07 +0100
Subject: [PATCH] - fix circular dependency check:   - remove successfully
 resolved objects from the resolve stack   - add special test case that checks
 for a situation where this could be wrong

---
 LightweightIocContainer/IocContainer.cs       | 18 +++--
 .../IocContainerRecursionTest.cs              | 67 +++++++++++++++++--
 2 files changed, 74 insertions(+), 11 deletions(-)

diff --git a/LightweightIocContainer/IocContainer.cs b/LightweightIocContainer/IocContainer.cs
index f828caf..0112cfd 100644
--- a/LightweightIocContainer/IocContainer.cs
+++ b/LightweightIocContainer/IocContainer.cs
@@ -207,25 +207,31 @@ namespace LightweightIocContainer
             else //not the first resolve call in chain but no circular dependencies for now
                 resolveStack.Add(typeof(T)); //add currently resolving type to the stack
 
+            T resolvedInstance;
+
             if (registration is IUnitTestCallbackRegistration<T> unitTestCallbackRegistration)
             {
-                return unitTestCallbackRegistration.UnitTestResolveCallback.Invoke(arguments);
+                resolvedInstance = unitTestCallbackRegistration.UnitTestResolveCallback.Invoke(arguments);
             }
             else if (registration is IDefaultRegistration<T> defaultRegistration)
             {
                 if (defaultRegistration.Lifestyle == Lifestyle.Singleton)
-                    return GetOrCreateSingletonInstance(defaultRegistration, arguments, resolveStack);
+                    resolvedInstance = GetOrCreateSingletonInstance(defaultRegistration, arguments, resolveStack);
                 else if (defaultRegistration is IMultitonRegistration<T> multitonRegistration && defaultRegistration.Lifestyle == Lifestyle.Multiton)
-                    return GetOrCreateMultitonInstance(multitonRegistration, arguments, resolveStack);
-
-                return CreateInstance(defaultRegistration, arguments, resolveStack);
+                    resolvedInstance = GetOrCreateMultitonInstance(multitonRegistration, arguments, resolveStack);
+                else
+                    resolvedInstance = CreateInstance(defaultRegistration, arguments, resolveStack);
             }
             else if (registration is ITypedFactoryRegistration<T> typedFactoryRegistration)
             {
-                return typedFactoryRegistration.Factory.Factory;
+                resolvedInstance = typedFactoryRegistration.Factory.Factory;
             }
             else
                 throw new UnknownRegistrationException($"There is no registration of type {registration.GetType().Name}.");
+
+            resolveStack.Remove(typeof(T)); //T was successfully resolved -> no circular dependency -> remove from resolve stack
+
+            return resolvedInstance;
         }
 
         /// <summary>
diff --git a/Test.LightweightIocContainer/IocContainerRecursionTest.cs b/Test.LightweightIocContainer/IocContainerRecursionTest.cs
index 3b1df3d..c14f189 100644
--- a/Test.LightweightIocContainer/IocContainerRecursionTest.cs
+++ b/Test.LightweightIocContainer/IocContainerRecursionTest.cs
@@ -14,7 +14,7 @@ namespace Test.LightweightIocContainer
     [TestFixture]
     public class IocContainerRecursionTest
     {
-        #region TestClasses
+        #region TestClassesCircularDependency
 
         [UsedImplicitly]
         public interface IFoo
@@ -44,7 +44,51 @@ namespace Test.LightweightIocContainer
             }
         }
 
-        #endregion TestClasses
+        #endregion TestClassesCircularDependency
+
+        #region TestClassesNonCircularDependency
+        
+        [UsedImplicitly]
+        public interface IA
+        {
+            
+        }
+
+        [UsedImplicitly]
+        public interface IB
+        {
+            
+        }
+
+        [UsedImplicitly]
+        public interface IC
+        {
+            
+        }
+
+        [UsedImplicitly]
+        private class A : IA
+        {
+            public A(IB b, IC c)
+            {
+            }
+        }
+
+        [UsedImplicitly]
+        private class B : IB
+        {
+            public B(IC c)
+            {
+            }
+        }
+
+        [UsedImplicitly]
+        private class C : IC
+        {
+
+        }
+
+        #endregion TestClassesNonCircularDependency
 
 
 
@@ -54,9 +98,6 @@ namespace Test.LightweightIocContainer
         public void SetUp()
         {
             _iocContainer = new IocContainer();
-
-            _iocContainer.Register<IFoo, Foo>();
-            _iocContainer.Register<IBar, Bar>();
         }
 
         [TearDown]
@@ -68,6 +109,9 @@ namespace Test.LightweightIocContainer
         [Test]
         public void TestCircularDependencies()
         {
+            _iocContainer.Register<IFoo, Foo>();
+            _iocContainer.Register<IBar, Bar>();
+
             CircularDependencyException exception = Assert.Throws<CircularDependencyException>(() => _iocContainer.Resolve<IFoo>());
             Assert.AreEqual(typeof(IFoo), exception.ResolvingType);
             Assert.AreEqual(2, exception.ResolveStack.Count);
@@ -81,9 +125,22 @@ namespace Test.LightweightIocContainer
             Assert.AreEqual(message, exception.Message);
         }
 
+        [Test]
+        public void TestNonCircularDependencies()
+        {
+            _iocContainer.Register<IA, A>();
+            _iocContainer.Register<IB, B>();
+            _iocContainer.Register<IC, C>();
+
+            IA a = _iocContainer.Resolve<IA>();
+        }
+
         [Test]
         public void TestRecursionWithParam()
         {
+            _iocContainer.Register<IFoo, Foo>();
+            _iocContainer.Register<IBar, Bar>();
+
             Assert.DoesNotThrow(() => _iocContainer.Resolve<IFoo>(new Mock<IBar>().Object));
             Assert.DoesNotThrow(() => _iocContainer.Resolve<IBar>(new Mock<IFoo>().Object));
         }