MainFile.cs

// This utility is build using Nunit framework like other NUnit tests.
// My main goal of this utility is, 
// if there is any exceptions then I have to fail my unit test.
// for any if conditions, instead of using a if...else, I have to fail my unit test.
// To achieve this, I am using Assert.Fail where ever necessary. Like few sample'e are below.
        
//if(value == null)
//{
      //Assert.Fail("Value cannot be null in this case"); 
      
   // I don't want to handle the code if the value is not null, instead 
   // I wanted it to fail my test. So far all good till here.
   // Real problem I have explained it in the Step class. See below.
//}

class Session
{
  private List<UseCase> useCaseList;
  
  public void ExecuteSession()
  {
    foreach(var useCase in useCaseList)
    {
      useCase.ExecuteUseCase();
    }
  }
}

class UseCase
{
  private List<Step> stepList;
  
  public void ExecuteUseCase()
  {
     var step = stepList[0];
     step.ExecuteStep();
  }

}

class Step
{
  private IServiceModel serviceModel;
  
  public Step()
  {
    serviceModel = new ServiceModel();
    serviceModel.SomeEventInModel += OnSomeEventInModelFired;
  }
  
  // Event handler
  private void OnSomeEventInModelFired(object sender, SomeEventInModelEventArgs args)
  {
     try
     {
        // Do some work and if any exception comes in this event handler. Catch block will catch it.
     }
     catch(Exception ex)
     {
        // If I call Assert.Fail(), internally Assert.Fail method throws FailedException.
        // Throwing exceptions from an event handler, causes the exception to propogate to the caller.
        // and my control never comes back to my unit test.
        // This is causing me a big problem. Now I wanted to know how to handle these kind of situations?
        // If I don't assert it here then my test thinks all are good and then will try to execute further code which I don't want.
        // Any thoughts on how to achieve this?
     }
  }
}