CODEWITHSUNDEEP
nservicebus
tom redfern
tom redfern

Reputation: 31750

nservicebus 3.2 testing expected failure

I want to test that handling a given instance of a message causes the handling to fail. However I can't see a way of doing this, as any exceptions thrown within the handler are not bubbled up to the testing code, and there doesn't appear to be anything built-in for this.

Ideally I'd like to do this:

Test.Handler<TransactionCreatedHandler>()
                    .ExpectFailure()
                    .OnMessage(financialTransaction, Guid.NewGuid().ToString());

I know the correct thing is to remove any processing code out of the handler and test that in isolation, but I'd still like to know if there's a way to do this.

Does anyone have any ideas?

Upvotes: 2

Views: 269

Answers (1)

tom redfern
tom redfern

Reputation: 31750

I have worked around this behavior by wrapping the Test.Handler in a try and catching a TargetInvocationException, then asserting against the InnerException. 

try
{
    Test.Handler<TransactionCreatedHandler>()
        .OnMessage(financialTransaction, Guid.NewGuid().ToString());
}
catch (TargetInvocationException ex)
{
    // Asserts against ex.InnerException
    ...
}

This obviously creates the risk that changes to NSB implementation will break these tests though it's one I'm willing to take on.

Incorporating comment from Daniel Marbach:

In version 5 and higher the behaviour changed. The testing library no longer throws a TargetInvocationException but the actual exception that happened in the handle method. Just a heads up –

Upvotes: 2

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