Unit testing for a publish method in mass transit using in memory bus - rabbitmq

Question

I am new to MassTransit and messaging. I am trying to write a unit test for a IBus.Publish and am not able to succeed with the result.
I am observing the fault from RabbitMQ and my observer looks like this:
public class FaultObserver : IReceiveObserver
{
public FaultObserver(IRequestUpdater statusUpdater,Lazy<IBus> bus)
{
this.statusUpdater = statusUpdater;
this.bus = bus;
}
public async Task ConsumeFault<T>(ConsumeContext<T> context, TimeSpan duration, string consumerType, Exception exception) where T : class
{
}
}
and my tests looks like the below code
var bus = fixture.Freeze<Mock<IBus>>();
bus.Setup(bu => bu.Publish<ReportFailedEvent>(It.IsAny<ReportFailedEvent>(),It.IsAny<CancellationToken>())).Verifiable();
var sut = fixture.Create<ReportRequestedFaultObserver>();
// Act
await sut.ConsumeFault(context.Object,new TimeSpan(0,0,1),string.Empty,exception);
// Assert
//bus.Verify(b => b.Publish<ReportFailedEvent>(It.IsAny<ReportFailedEvent>(), It.IsAny<CancellationToken>()), Times.Exactly(1));
bus.Verify(b =>b.Publish<ReportFailedEvent>(new ReportFailedEvent(request,exception.Message),It.IsAny<CancellationToken>()),Times.Once());
my setup looks like
[SetUp]
public void SetUp()
{
fixture.Customize(new AutoMoqCustomization());
var inMemoryTransportCache = new InMemoryTransportCache(Environment.ProcessorCount);
bus = Bus.Factory.CreateUsingInMemory(configure =>
{
configure.SetTransportProvider(inMemoryTransportCache);
configure.ReceiveEndpoint("input_queue", configurator =>
{
configurator.Handler<(cc =>
{
});
});
});
bus.Start().Ready.Wait();
}
I am not able to mock my Publish method. Does anyone knows what I am doing wrong?

Answer 1

Your mock for the bus is wrong. It should be:
bus.Setup(bu => bu.Publish<ReportFailedEvent>(
It.IsAny<object>(), It.IsAny<CancellationToken>()));
Publish takes an object and a CancellationToken, as per the interface definition in MassTransit:
Task Publish(object message, CancellationToken cancellationToken = default(CancellationToken));
Also, if you want to check the contents of the message, you can use the Moq Callback extension:
ReportFailedEvent message = null;
bus
.Setup(bu => bu.Publish<ReportFailedEvent>(It.IsAny<object>(), It.IsAny<CancellationToken>()))
.Callback<object, CancellationToken>((a, b) => { message = a as ReportFailedEvent; });
//.. your system under test code....
Assert.That(message.Property, Is.EqualTo(expectation));
If you are setting the priority, the MassTransit interface looks like this:
public static Task Publish<T>(
this IPublishEndpoint endpoint,
T message,
Action<PublishContext<T>> callback,
CancellationToken cancellationToken = default(CancellationToken))
where T : class;
And an example would be:
bus.Publish<ReportFailedEvent>(message, context =>
{
context.SetPriority(messagePriority.Priority);
});
And the accompanying Moq is:
ReportFailedEvent message = null;
bus
.Setup(bu => bu.Publish<ReportFailedEvent>(It.IsAny<object>(), It.IaAny<Action<PublishContext<ReportFailedEvent>>>(), It.IsAny<CancellationToken>()))
.Callback<object, Action<PublishContext<ReportFailedEvent>>, CancellationToken>((a, b, c) => { message = a as ReportFailedEvent; });
Just as a side note, ideally you should be publishing the interfaces rather than classes, so IReportFailedEvent rather than ReportFailedEvent.