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.