Updated event raising logic to only allow internal default constructors

Author: Mihnea Rădulescu

src/NSubstitute/Core/Events/RaiseEventWrapper.cs

@@ -12,7 +12,7 @@ protected EventArgs GetDefaultForEventArgType(Type type)
     {
         if (type == typeof(EventArgs)) return EventArgs.Empty;
 
-        var defaultConstructor = GetPublicDefaultConstructor(type) ?? GetNonPublicDefaultConstructor(type);
+        var defaultConstructor = GetPublicDefaultConstructor(type) ?? GetInternalDefaultConstructor(type);
         if (defaultConstructor is null)
         {
             var message = string.Format(
@@ -24,10 +24,19 @@ protected EventArgs GetDefaultForEventArgType(Type type)
         return (EventArgs)defaultConstructor.Invoke([]);
     }
 
+    private static ConstructorInfo? GetInternalDefaultConstructor(Type type)
+    {
+        var nonPublicDefaultConstructor = GetNonPublicDefaultConstructor(type);
+        var isInternalDefaultConstructor = nonPublicDefaultConstructor?.IsAssembly == true;
+        return isInternalDefaultConstructor ? nonPublicDefaultConstructor : null;
+    }
+
     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.ExactBinding | bindingFlags, null, Type.EmptyTypes, null);

tests/NSubstitute.Acceptance.Specs/EventRaising.cs

@@ -299,17 +299,28 @@ public void Raise_custom_event_that_has_sender_and_args_but_does_not_inherit_fro
     }
 
     [Test]
-    public void MyEvent_With_CustomEventArgsWithNonPublicDefaultConstructor_IsRaised()
+    public void MyEvent_with_CustomEventArgsWithInternalDefaultConstructor_is_raised()
     {
         // Arrange
-        IExample mockExample = Substitute.For<IExample>();
-        var consumer = new Consumer(mockExample);
+        var exampleInternalMock = Substitute.For<IExampleInternal>();
+        var consumerInternal = new ConsumerInternal(exampleInternalMock);
 
         // Act
-        mockExample.MyEvent += Raise.EventWith<CustomEventArgsWithInternalDefaultConstructor>(this, null!);
+        exampleInternalMock.MyEvent += Raise.EventWith<CustomEventArgsWithInternalDefaultConstructor>(this, null!);
 
         // Assert
-        Assert.That(consumer.SomethingWasDone);
+        Assert.That(consumerInternal.SomethingWasDone);
+    }
+
+    [Test]
+    public void MyEvent_with_CustomEventArgsWithPrivateDefaultConstructor_throws_CannotCreateEventArgsException()
+    {
+        // Arrange
+        var examplePrivateMock = Substitute.For<IExamplePrivate>();
+
+        // Act and Assert
+        Assert.Throws<CannotCreateEventArgsException>(() =>
+            examplePrivateMock.MyEvent += Raise.EventWith<CustomEventArgsWithPrivateDefaultConstructor>(this, null!));
     }
 
     class RaisedEventRecorder<T>
@@ -358,13 +369,13 @@ public class CustomEventArgsWithInternalDefaultConstructor : EventArgs
     {
         internal CustomEventArgsWithInternalDefaultConstructor() { }
     }
-    public interface IExample
+    public interface IExampleInternal
     {
         public event EventHandler<CustomEventArgsWithInternalDefaultConstructor> MyEvent;
     }
-    public class Consumer
+    public class ConsumerInternal
     {
-        public Consumer(IExample example)
+        public ConsumerInternal(IExampleInternal example)
         {
             example.MyEvent += OnMyEvent;
         }
@@ -378,4 +389,13 @@ private void DoSomething()
             SomethingWasDone = true;
         }
     }
+
+    public class CustomEventArgsWithPrivateDefaultConstructor : EventArgs
+    {
+        private CustomEventArgsWithPrivateDefaultConstructor() { }
+    }
+    public interface IExamplePrivate
+    {
+        public event EventHandler<CustomEventArgsWithPrivateDefaultConstructor> MyEvent;
+    }
 }