From b3e9e8127cdb741126222c057e9d496f7d4f32c0 Mon Sep 17 00:00:00 2001
From: Simon G <simon.gockner@gmail.com>
Date: Fri, 17 Dec 2021 14:18:50 +0100
Subject: [PATCH] - fix bug where singletons could be created multiple times

---
 LightweightIocContainer/IocContainer.cs       |  4 ++
 .../LightweightIocContainer.csproj            |  2 +-
 README.md                                     |  4 +-
 .../MultiLayerResolveTest.cs                  | 41 ++++++++++++++-----
 .../Test.LightweightIocContainer.csproj       |  2 +-
 5 files changed, 39 insertions(+), 14 deletions(-)

diff --git a/LightweightIocContainer/IocContainer.cs b/LightweightIocContainer/IocContainer.cs
index 87a260c..7619dd1 100644
--- a/LightweightIocContainer/IocContainer.cs
+++ b/LightweightIocContainer/IocContainer.cs
@@ -203,6 +203,10 @@ namespace LightweightIocContainer
         /// <returns>A recursively resolved instance of the given <see cref="Type"/></returns>
         private T ResolvePlaceholder<T>(InternalToBeResolvedPlaceholder toBeResolvedPlaceholder)
         {
+            object? existingInstance = TryGetExistingInstance<T>(toBeResolvedPlaceholder.ResolvedRegistration, toBeResolvedPlaceholder.Parameters);
+            if (existingInstance is T instance)
+                return instance;
+
             if (toBeResolvedPlaceholder.Parameters == null)
                 return CreateInstance<T>(toBeResolvedPlaceholder.ResolvedRegistration, null);
             
diff --git a/LightweightIocContainer/LightweightIocContainer.csproj b/LightweightIocContainer/LightweightIocContainer.csproj
index 971d98b..f65b55b 100644
--- a/LightweightIocContainer/LightweightIocContainer.csproj
+++ b/LightweightIocContainer/LightweightIocContainer.csproj
@@ -9,7 +9,7 @@
     <LangVersion>default</LangVersion>
     <Nullable>enable</Nullable>
     <DocumentationFile>LightweightIocContainer.xml</DocumentationFile>
-    <VersionPrefix>3.0.0</VersionPrefix>
+    <VersionPrefix>3.0.1</VersionPrefix>
   </PropertyGroup>
 
   <PropertyGroup>
diff --git a/README.md b/README.md
index 07f6d2e..1fcb349 100644
--- a/README.md
+++ b/README.md
@@ -16,13 +16,13 @@ The easiest way to [install](https://github.com/SimonG96/LightweightIocContainer
 You can either use the [`PackageManager`](https://github.com/SimonG96/LightweightIocContainer/wiki/Install-Lightweight-IOC-Container#packagemanager) in VisualStudio:
 
 ```PM
-PM> Install-Package LightweightIocContainer -Version 3.0.0
+PM> Install-Package LightweightIocContainer -Version 3.0.1
 ```
 
 or you can use the [`.NET CLI`](https://github.com/SimonG96/LightweightIocContainer/wiki/Install-Lightweight-IOC-Container#net-cli):
 
 ```.net
-> dotnet add package LightweightIocContainer --version 3.0.0
+> dotnet add package LightweightIocContainer --version 3.0.1
 ```
 
 ### Example usage
diff --git a/Test.LightweightIocContainer/MultiLayerResolveTest.cs b/Test.LightweightIocContainer/MultiLayerResolveTest.cs
index 3c7d857..1e7181c 100644
--- a/Test.LightweightIocContainer/MultiLayerResolveTest.cs
+++ b/Test.LightweightIocContainer/MultiLayerResolveTest.cs
@@ -13,12 +13,12 @@ public class MultiLayerResolveTest
 {
     public interface IA
     {
-        
+        IB BProperty { get; }
     }
     
     public interface IB
     {
-        
+        C C { get; }
     }
     
     [UsedImplicitly]
@@ -36,19 +36,28 @@ public class MultiLayerResolveTest
     [UsedImplicitly]
     private class A : IA
     {
-        [UsedImplicitly]
-        private readonly IB _b;
-        
-        public A(IBFactory bFactory) => _b = bFactory.Create(new C("from A"));
+        public A(IBFactory bFactory) => BProperty = bFactory.Create(new C("from A"));
+        public IB BProperty { get; }
+    }
+    
+    private class OtherA : IA
+    {
+        public OtherA(IB bProperty, IB secondB)
+        {
+            BProperty = bProperty;
+            SecondB = secondB;
+        }
+
+        public IB BProperty { get; }
+        public IB SecondB { get; }
     }
 
     [UsedImplicitly]
     private class B : IB
     {
-        public B(C c)
-        {
-            
-        }
+        public B(C c) => C = c;
+
+        public C C { get; }
     }
     
     [UsedImplicitly]
@@ -82,4 +91,16 @@ public class MultiLayerResolveTest
         IB b = container.Resolve<IB>();
         Assert.IsInstanceOf<B>(b);
     }
+
+    [Test]
+    public void TestResolveSingletonTwiceAsCtorParameterInSameCtor()
+    {
+        IocContainer container = new();
+        container.Register(r => r.Add<IA, OtherA>());
+        container.Register(r => r.Add<IB, B>());
+        container.Register(r => r.Add<C>(Lifestyle.Singleton).WithParameters("test"));
+
+        OtherA a = container.Resolve<OtherA>();
+        Assert.AreEqual(a.BProperty.C, a.SecondB.C);
+    }
 }
\ No newline at end of file
diff --git a/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj b/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj
index 247e803..1a7b1cd 100644
--- a/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj
+++ b/Test.LightweightIocContainer/Test.LightweightIocContainer.csproj
@@ -5,7 +5,7 @@
     <IsPackable>false</IsPackable>
     <Authors>SimonG</Authors>
     <LangVersion>default</LangVersion>
-    <VersionPrefix>3.0.0</VersionPrefix>
+    <VersionPrefix>3.0.1</VersionPrefix>
   </PropertyGroup>
 
   <ItemGroup>