[mocha-developer] how does Mocha compare in terms of classical vs mock-based testing, and stubbing???

James Mead jamesmead44 at gmail.com
Mon Feb 5 07:52:44 EST 2007

On 05/02/07, Greg Hauptmann <greg.hauptmann.ruby at gmail.com> wrote:
> I've just been reading Martin Fowler's article re mock versus
> stubbing<http://martinfowler.com/articles/mocksArentStubs.html>where
> he compares traditional TDD testing techniques with mock based
> testing. I'd be interested in comments from a ruby on rails perspective in
> terms of this and Mocha?  For example:
> a) Do you see Mocha as a robust way to test Ruby on Rails based apps?
> b) Why would one use Mocha over traditional non-mock object based testing
> for Ruby on Rails?
> c) Is Mocha a good choice for stubbing out other components that the rails
> app may interact with, for the purpose of testing?

Hi Greg,

Some great questions!

The team at reevoo.com has been using Mocha and its earlier incarnations to
help us test drive Rails applications over the last 18 months or so. We find
it useful to be able to do interaction-based testing as well as traditional
state-based testing. But you could use any mocking library to achieve the
same effect. In general terms, I think doing interaction-based TDD can help
you write more cohesive, less coupled code, although of course it's not a
silver bullet. You will still need higher level functional/integration tests
which check that the real objects are all wired up correctly. I would say
you will see more benefits of using an interaction-based approach, the
bigger your application gets - mainly due to the reduction in coupling and
hence the reduction in brittleness of tests.

There are some great resources on the JMock & MockObjects websites (see
http://www.jmock.org/docs.html and http://www.mockobjects.com/) which
although they give examples in Java, are just as applicable in Ruby. In
particular the "Mock Roles, Not Objects" paper (
http://www.jmock.org/oopsla2004.pdf) is well worth a read.

I'm not sure I've completely answered your questions, but please feel free
to ask more questions like this on the mailing list. I find it's often
easier to talk about specific examples rather than generalities, so why not
have a go with Mocha in a Rails app and drop us a line if you have any


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