From 54d9e2cc0167f60ca2e1d031c740aaf3cf31c26f Mon Sep 17 00:00:00 2001
From: Beth Maloney <beth.maloney@interfisystems.com>
Date: Thu, 29 Feb 2024 12:41:36 +1100
Subject: [PATCH] Replace Constructor Info Invoke with CreateInstance

---
 .../Utils/ExtensionsTests.cs                  | 48 +++++++++++++++++++
 .../MissingConstructorException.cs            |  8 +++-
 src/FluentNHibernate/Utils/Extensions.cs      | 16 ++++---
 3 files changed, 63 insertions(+), 9 deletions(-)
 create mode 100644 src/FluentNHibernate.Testing/Utils/ExtensionsTests.cs

diff --git a/src/FluentNHibernate.Testing/Utils/ExtensionsTests.cs b/src/FluentNHibernate.Testing/Utils/ExtensionsTests.cs
new file mode 100644
index 000000000..19c3f0a02
--- /dev/null
+++ b/src/FluentNHibernate.Testing/Utils/ExtensionsTests.cs
@@ -0,0 +1,48 @@
+using NUnit.Framework;
+using FluentNHibernate.Utils;
+
+namespace FluentNHibernate.Testing.Utils;
+
+[TestFixture]
+public class ExtensionsTests
+{
+    class PublicConstructor
+    {
+        public PublicConstructor() { }
+    }
+
+    class PrivateConstructor
+    {
+        private PrivateConstructor() { }
+    }
+
+    class ConstructorWithArguments
+    {
+        private ConstructorWithArguments(int number) { }
+    }
+
+    [Test]
+    public void CanInitialiseClass()
+    {
+        var type = typeof(PublicConstructor);
+        var result = type.InstantiateUsingParameterlessConstructor();
+
+        Assert.That(result, Is.InstanceOf<PublicConstructor>());
+    }
+
+    [Test]
+    public void CanInitialiseClassWithPrivateConstructor()
+    {
+        var type = typeof(PrivateConstructor);
+        var result = type.InstantiateUsingParameterlessConstructor();
+
+        Assert.That(result, Is.InstanceOf<PrivateConstructor>());
+    }
+
+    [Test]
+    public void ClassWithoutParameterlessConstructorThrowsException()
+    {
+        var type = typeof(ConstructorWithArguments);
+        Assert.Throws<MissingConstructorException>(() => type.InstantiateUsingParameterlessConstructor());
+    }
+}
diff --git a/src/FluentNHibernate/MissingConstructorException.cs b/src/FluentNHibernate/MissingConstructorException.cs
index 9296b8dc6..586cc666e 100644
--- a/src/FluentNHibernate/MissingConstructorException.cs
+++ b/src/FluentNHibernate/MissingConstructorException.cs
@@ -8,8 +8,12 @@ public class MissingConstructorException : Exception
 {
     public MissingConstructorException(Type type)
         : base("'" + type.AssemblyQualifiedName + "' is missing a parameterless constructor.")
-    {}
+    { }
+
+    public MissingConstructorException(Type type, Exception innerException)
+        : base("'" + type.AssemblyQualifiedName + "' is missing a parameterless constructor.", innerException)
+    { }
 
     protected MissingConstructorException(SerializationInfo info, StreamingContext context) : base(info, context)
-    {}
+    { }
 }
diff --git a/src/FluentNHibernate/Utils/Extensions.cs b/src/FluentNHibernate/Utils/Extensions.cs
index 8b82f4ef1..096c277e4 100644
--- a/src/FluentNHibernate/Utils/Extensions.cs
+++ b/src/FluentNHibernate/Utils/Extensions.cs
@@ -53,12 +53,14 @@ public static T InstantiateUsingParameterlessConstructor<T>(this Type type)
 
     public static object InstantiateUsingParameterlessConstructor(this Type type)
     {
-        var constructor = ReflectHelper.GetDefaultConstructor(type);
-
-        if (constructor == null)
-            throw new MissingConstructorException(type);
-
-        return constructor.Invoke(null);
+        try
+        {
+            return Activator.CreateInstance(type, true);
+        }
+        catch (MissingMethodException ex)
+        {
+            throw new MissingConstructorException(type, ex);
+        }
     }
 
     public static bool HasInterface(this Type type, Type interfaceType)
@@ -75,7 +77,7 @@ public static T DeepClone<T>(this T obj)
 #if NETFRAMEWORK
             var formatter = new BinaryFormatter();
 #else
-                var formatter = new BinaryFormatter(new NetStandardSerialization.SurrogateSelector(), new StreamingContext());
+            var formatter = new BinaryFormatter(new NetStandardSerialization.SurrogateSelector(), new StreamingContext());
 #endif
 
             formatter.Serialize(stream, obj);