Raise.EventWith default constructor (#788)

src/NSubstitute/Core/Events/RaiseEventWrapper.cs

@@ -12,8 +12,8 @@ protected EventArgs GetDefaultForEventArgType(Type type)
     {
         if (type == typeof(EventArgs)) return EventArgs.Empty;
 
-        var defaultConstructor = GetDefaultConstructor(type);
-        if (defaultConstructor == null)
+        var defaultConstructor = GetPublicDefaultConstructor(type) ?? GetNonPublicDefaultConstructor(type);
+        if (defaultConstructor is null)
         {
             var message = string.Format(
                 "Cannot create {0} for this event as it has no default constructor. " +
@@ -24,7 +24,12 @@ protected EventArgs GetDefaultForEventArgType(Type type)
         return (EventArgs)defaultConstructor.Invoke([]);
     }
 
-    private static ConstructorInfo? GetDefaultConstructor(Type type) => type.GetConstructor(Type.EmptyTypes);
+    private static ConstructorInfo? GetPublicDefaultConstructor(Type type)
+        => GetDefaultConstructor(type, BindingFlags.Public);
+    private static ConstructorInfo? GetNonPublicDefaultConstructor(Type type)
+        => GetDefaultConstructor(type, BindingFlags.NonPublic);
+    private static ConstructorInfo? GetDefaultConstructor(Type type, BindingFlags bindingFlags)
+        => type.GetConstructor(BindingFlags.Instance | bindingFlags, null, Type.EmptyTypes, null);
 
     protected static void RaiseEvent(RaiseEventWrapper wrapper)
     {

tests/NSubstitute.Acceptance.Specs/EventRaising.cs

@@ -298,6 +298,20 @@ public void Raise_custom_event_that_has_sender_and_args_but_does_not_inherit_fro
         Assert.That(eventRecorder.Sender, Is.SameAs(sender));
     }
 
+    [Test]
+    public void MyEvent_With_CustomEventArgsWithInternalDefaultConstructor_IsRaised()
+    {
+        // Arrange
+        IExample mockExample = Substitute.For<IExample>();
+        var consumer = new Consumer(mockExample);
+
+        // Act
+        mockExample.MyEvent += Raise.EventWith<CustomEventArgsWithInternalDefaultConstructor>(this, null!);
+
+        // Assert
+        Assert.That(consumer.SomethingWasDone);
+    }
+
     class RaisedEventRecorder<T>
     {
         public object Sender;
@@ -340,4 +354,29 @@ public class CustomEventArgsWithNoDefaultCtor : EventArgs
     {
         public CustomEventArgsWithNoDefaultCtor(string arg) { }
     }
+
+    public class CustomEventArgsWithInternalDefaultConstructor : EventArgs
+    {
+        internal CustomEventArgsWithInternalDefaultConstructor() { }
+    }
+    public interface IExample
+    {
+        public event EventHandler<CustomEventArgsWithInternalDefaultConstructor> MyEvent;
+    }
+    public class Consumer
+    {
+        public Consumer(IExample example)
+        {
+            example.MyEvent += OnMyEvent;
+        }
+        public bool SomethingWasDone { get; private set; }
+        private void OnMyEvent(object sender, CustomEventArgsWithInternalDefaultConstructor args)
+        {
+            DoSomething();
+        }
+        private void DoSomething()
+        {
+            SomethingWasDone = true;
+        }
+    }
 }