.RaiseAsync throws exception when used with a void delegate, no exception info for wrong using

[Keugon]

Describe the Bug

When raising a event with .RaiseAsync() with a void Delegate like public delegate void MySampleDelegate(int nummer, bool istAktiviert); the .RaiseAsync() methode gives a System.NullReferenceException because it expects a delegate with Task as return type

Steps to Reproduce

[TestClass]
public sealed class ReproTest
{
  [TestMethod]
  public async Task TestMethod1()
  {
    Mock<ICommunicator> mockCommunicator = new Mock<ICommunicator>();
    WorkingClass proband = new WorkingClass(mockCommunicator.Object);

    await mockCommunicator.RaiseAsync(e => e.VaccumPumpActivationEvent += null, 1, true);

  }
}

public class WorkingClass
{
  private readonly ICommunicator _Communicator;
  public WorkingClass(ICommunicator kommunikator)
  {
    this._Communicator = kommunikator;
    this._Communicator.VaccumPumpActivationEvent += this.Event_VaccumPumpActivation;
  }

  private void Event_VaccumPumpActivation(int nummer, bool istAktiviert)
  {
    Console.WriteLine($"EventFired with {nummer}, and {istAktiviert}");
  }
}

public delegate void VaccumPumpActivationDelegate(int nummer, bool istAktiviert);
public interface ICommunicator
{
  public event VaccumPumpActivationDelegate VaccumPumpActivationEvent;
}

Expected Behavior

The .RaiseAsync() methode should describe that such a Exception can occur and the Exception should contain a informativ description why it doesnt work eg. Event is not of return type Task.

Exception with Stack Trace

System.NullReferenceException
  HResult=0x80004003
  Message = Object reference not set to an instance of an object.
  Source = ConsoleAppBastelProjekt.UnitTests
  Stacktrace:
   bei ConsoleAppBastelProjekt.UnitTests.Test1.<TestMethod1>d__0.MoveNext() in D:\Git\ForeignRepos\ConsoleAppBastelProjekt\ConsoleAppBastelProjekt.UnitTests\Test1.cs: Zeile14

Version Info

Application Project tested with .net8 and ´.net9´ Test Project

<ItemGroup>
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" Version="17.12.6" />
    <PackageReference Include="Microsoft.Testing.Extensions.TrxReport" Version="1.4.3" />
    <PackageReference Include="Moq" Version="4.20.72" />
    <PackageReference Include="MSTest" Version="3.6.4" />
  </ItemGroup>

Additional Info

This Issue got originaly resolved and explained to me in this Thread https://stackoverflow.com/questions/79680262/moq-raiseasync-results-in-system-nullreferenceexception-moq-raise-works-fine/

[andrewhickman-aveva]

Unfortunately using Raise in an async method causes warnings from at least two analysers suggesting use of RaiseAsync instead, even when Raise is more appropriate. See CA1849 and S6966. There is an issue on the sonar-dotnet repository about this #9697