Mocking Methods that Don't Exist with RSpec

I've done some tests/specs using RSpec in Ruby with Mock Objects, but until I read this message on the RSpec List it hadn't occurred to me that you could mock methods (messages) that aren't present in the class itself.

I guess you could see that as a natural consequence of the kind of duck-typing system that dynamic languages offer, but it's a little awkward. You can end up, as the poster suggests, with a view that's out of sync with your model, and tests that don't pick it up.

As a result, not only do dynamic languages make testing more important, they make integration testing more important. Interesting.

I'd be interested to see a large codebase written entirely in Ruby and get a sense for the comprehensiveness and duration of a test run -- within three months of writing tests and specs on a Ruby/Rest project, we'd already racked up a five-minute test run (but, hey, we were Ruby newbies, so I'd be surprised to discover that people who've been at it longer have good strategies for maximizing test comprehensiveness and minimizing test-run time.