Unit Testing, Agile Development, Leadership & .NET - By Roy Osherove
Bizmock is really nice, because it reduces the need to worry about external systems. It does take a fair amount of upfront work to define all the artifacts that need to be mocked.
Bizmonade is really quite cool, but it is still new enough that it doesn't support what I would consider good coding practices, such as using multi-part messages.
Last but not least, BizUnit has been around for a long time, and was for us BizTalk developers the only testing framework for use to use. There is a codeplex project called BooUnit that is a DSL for BizUnit (No XML for tests).
BTW, the DeploymentItem you see in the BizMock samples are the XML message instances used to kick-off the process. The real reason it is to be considered integration type tests is that you still have to deploy all the code to BizTalk and create the configuration. It basically is a an Adapter that allows you to write unit tests that recieve and respond to requests.
As BizTalks connects between systems - XML is not as bad as it sounds - this is when other guys should create the unit test data for you (as you are testing their interface) - and these guys have not necessary even anything like .NET and XML is at least better than pure text files or csv.