Expected exceptions

- [Voiceover] XUnit has an interesting approach…to exception-handling for unit tests.…It's different from the MS Test technique.…For a discussion of the philosophy…of unit tests and exceptions,…watch the expected exceptions video in the MS Test chapter.…I'll review what's happening in Brokerage Lib.…In this method determined variable rate,…I check whether the unit sold is less than zero,…and I also check whether the unit price is less than zero,…and if either of those conditions is true,…I throw the argument out of range exception.…Over in my unit test, I verify…that that exception is thrown by using…this expected exception attribute on my test method.…

I tell it I'm looking for argument out of range exception.…This states that the system under…test will throw this exception.…Let's review what happens when you have…an un-handled exception in your code.…Let's say that the exception is thrown on line ten.…Since there's no handler for it inside this method,…none of the rest of the code in this method will run.…That's also true over here in my test method.…