Replace Constructor Info Invoke with CreateInstance (#646)

+semver:patch

Author: bethmaloney

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());
+    }
+}

src/FluentNHibernate/MissingConstructorException.cs

@@ -10,6 +10,10 @@ 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)
+    { }
+
     [Obsolete("This API supports obsolete formatter-based serialization and will be removed in a future version")]
     protected MissingConstructorException(SerializationInfo info, StreamingContext context) : base(info, context)
     { }

src/FluentNHibernate/Utils/Extensions.cs

@@ -59,12 +59,14 @@ public static T InstantiateUsingParameterlessConstructor<T>(this Type type)
 
     public static object InstantiateUsingParameterlessConstructor(this Type type)
     {
-        var constructor = ReflectHelper.GetDefaultConstructor(type);
-
-        if (constructor is 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)
@@ -81,7 +83,7 @@ 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);