[TestClass]
public class Repro
{
   public delegate void EventDelegate();

   public class Tester
   {
      public event EventDelegate TestEventDelegate;
      public event EventHandler TestEventHandler;

      public void RaiseEventDelegate()
      {
         TestEventDelegate?.Invoke();
      }

      public void RaiseEventHandler()
      {
         TestEventHandler?.Invoke( this, EventArgs.Empty );
      }
   }

   [TestMethod]
   public void TestRaiseEventDelegate()
   {
      var tester  = new Tester();
      var monitor = tester.Monitor();

      tester.RaiseEventDelegate();

      monitor.Should().Raise( nameof( Tester.TestEventDelegate ) );
   }

   [TestMethod]
   public void RaiseEventEventHandler()
   {
      var tester  = new Tester();
      var monitor = tester.Monitor();

      tester.RaiseEventHandler();

      monitor.Should().Raise( nameof( Tester.TestEventHandler ) );
   }
}