Testing your Akka.NET system using EventFilter

Although Akka.NET has built-in support for testing, it is sometimes hard to find out what’s really going on inside your actor system.

A useful feature that can help you solve this problem during integration testing is the EventFilter. The EventFilter is a tool to verify that actors write certain log messages. It can also detect if messages go to DeadLetters and if certain exceptions are thrown.

2 examples:

	[Test]
	public void MailActor_Should_Log_MailSent()
	{
	var mailActor = ActorOf(Props.Create<MailActor>());
	var options = CreateOptions();
	var mail = CreateMail();
	var message = new SendMailMessage(mail, options);
	EventFilter.Info("mail sent").ExpectOne(() =>
	{
	mailActor.Tell(message);
	});
	}

view raw EventFilterSample1.cs hosted with ❤ by GitHub

	[Test]
	public void MailActor_Should_Throw_Exception_When_SMTPConfiguration_Is_Missing()
	{
	var mailActor = ActorOf(Props.Create<MailActor>());
	var options = CreateOptions();
	var mail = CreateMail();
	var message = new SendMailMessage(mail, options);
	EventFilter.Exception<SMTPException>()
	.ExpectOne(() => mailActor.Tell(message));
	}

view raw EventFilterSample2.cs hosted with ❤ by GitHub

Remark: By default the event filter searches for exact matches.