[rspec-users] testing behaviour or testing code?

David Chelimsky dchelimsky at gmail.com
Sun Sep 2 03:56:58 EDT 2007

On 9/2/07, Pat Maddox <pergesu at gmail.com> wrote:
> On 8/24/07, David Chelimsky <dchelimsky at gmail.com> wrote:
> > On 8/24/07, Pat Maddox <pergesu at gmail.com> wrote:
> > > On 8/24/07, David Chelimsky <dchelimsky at gmail.com> wrote:
> > > > describe Widget, "class" do
> > > >   it "should provide a list of widgets sorted alphabetically" do
> > > >     Widget.should_receive(:find).with(:order => "name ASC")
> > > >     Widget.find_alphabetically
> > > >   end
> > > > end
> > > >
> > > > You're correct that the refactoring requires you to change the
> > > > object-level examples, and that is something that would be nice to
> > > > avoid. But also keep in mind that in java and C# people refactor
> > > > things like that all the time without batting an eye, because the
> > > > tools make it a one-step activity. Refactoring is changing the design
> > > > of your *system* without changing its behaviour. That doesn't really
> > > > fly all the way down to the object level 100% of the time.
> > > >
> > > > WDYT?
> > >
> > > I think that example is fine up until the model spec.  The
> > > find_alphabetically example should hit the db, imo.  With the current
> > > spec there's no way to know whether find_alphabetically actually works
> > > or not.  You're relying on knowledge of ActiveRecord here, trusting
> > > that the arguments to find are correct.
> >
> > Au contrare! This all starts with an Integration Test. I didn't post
> > the code but I did mention it.
> >
> > > What I've found when I write specs is that I discover new layers of
> > > services until eventually I get to a layer that actually does
> > > something.  When I get there, it's important to have specs that
> > > describe what it does, not how it does it.  In the case of
> > > find_alphabetically we care that it returns the items in alphabetical
> > > order.  Not that it makes a certain call to the db.
> >
> > I play this both ways and haven't come to a preference, but I'm
> > leaning towards blocking database access from the rspec examples and
> > only allowing it my end to end tests (using Rails Integration Tests or
> > - soon - RSpec's new Story Runner).
> Now that I've had a chance to play with Story Runner, I want to
> revisit this topic a bit.
> Let's say in your example you wanted to refactor find_alphabetically
> to use enumerable's sort_by to do the sorting.
> def self.find_alphabetically
>   find(:all).sort_by {|w| w.name }
> end
> Your model spec will fail, but your integration test will still pass.
> I've been thinking about this situation a lot over the last few
> months.  It's been entirely theoretical because I haven't had a suite
> of integration tests ;)  Most XP advocates lean heavily on unit tests
> when doing refactoring.  Mocking tends to get in the way of
> refactoring though.  In the example above, we rely on the integration
> test to give us confidence while refactoring.  In fact I would ignore
> the unit test (model-level spec) altogether, and rewrite it when the
> refactoring is complete.
> Here's how I reconcile this with traditional XP unit testing.  First
> of all our integration tests are relatively light weight.  In a web
> app, a user story consists of making a request and verifying the
> response.  Authentication included, you'll be making at most 3-5 HTTP
> requests per test.  This means that our integration tests still run in
> just a few seconds.  Integration tests in a Rails app are a completely
> different beast from the integration tests in the Chrysler payroll app
> that Beck, Jeffries, et al worked on.
> The second point of reconciliation is that mock objects and
> refactoring are two distinct tools you use to design your code.  When
> I'm writing greenfield code I'll use mocks to drive the design.  When
> I refactor though, I'm following known steps to improve the design of
> my existing code.  The vast majority of the time I will perform a
> known refactoring, which means I know the steps and the resulting
> design.  In this situation I'll ignore my model specs because they'll
> blow up, giving me no information other than I changed the design of
> my code.  I can use the integration tests to ensure that I haven't
> broken any behavior.  At this point I would edit the model specs to
> use the correct mock calls.
> As I mentioned, this has been something that's been on my mind for a
> while.  I find mock objects to be very useful, but they seem to clash
> with most of the existing TDD and XP literature.  To summarize, here
> are the points where I think they clash:
> * Classical TDD relies on unit tests for confidence in refactoring.
> BDD relies on integration tests
> * XP acceptance tests are customer tests, whereas RSpec User Stories
> are programmer tests.  They can serve a dual-purpose because you can
> easily show them to a customer, but they're programmer tests in the
> sense that the programmer writes and is responsible for those
> particular tests.
> In the end it boils down to getting stuff done.  After a bit of
> experimentation I'm thinking that the process of
> 1. Write a user story
> 2. Write detailed specs using mocks to drive design
> 3. Refactor, using stories to ensure that expected behavior is
> maintained, ignoring detailed specs
> 4. Retrofit specs with correct mock expectations
> is a solid approach.  I'd like others to weigh in with their thoughts.

Hey Pat,

I really appreciate that you're thinking about and sharing this as its
something that weighs on a lot of people's minds and it's clear that
you have some understanding of the XP context in which all of this was

That said, I see this quite a bit differently.

I don't think this has anything to do w/ TDD vs BDD. "Mock Objects" is
not a BDD concept. It just feels that way because we talk more about
interaction testing, but interaction testing predates BDD by some
years. The problem we experience with mocks relates to the fact that
we've chosen to live in the beautiful, free, dynamically typed and
POORLY TOOLED land of Ruby. When Ruby refactoring tools catch up with
those of java and .NET, this pain will all go away.

For example - if I'm in IntelliJ in a java project and I have a method
like this:


and I'm using jmock (the old version), which uses Strings for method names:

  model.expects(once()).method("getName").will(returnValue("stub value"))

and I do a Rename Method refactoring on getName(), IntelliJ will ask
me if I want to change the strings it finds that match getName as well
as the method invocations.

In Ruby, we do this now w/ search and replace. Not quite as elegant.
But under the hood, that's all IntelliJ is doing. It just makes it
feel like an integrated step of an automated refactoring.

re: Story Runner. The intent of Story Runner is exactly the same as
tools like FIT, etc, that are typically found in the Acceptance
Testing space in XP projects. In my experience using FitNesse, it was
rare that a customer actually added new tests to a suite. If there
were testing folks on board, they would do it (and they would likely
be equipped to do it in Story Runner as well), but if not, then the
FitNesse tests were at best the result of a collaborative session with
the customer and, at worst, our (developers), interpretation of
conversations we had had with the customer.

I see Story Runner fitting in exactly like that in the short run. I
can also see external DSLs emerging that let customers actually write
the outputs that Story Runner should produce and run that through a
process that writes what we're writing now in Story Runner. But that's
probably some time off.

I totally agree with your last statement that "it boils down to
getting stuff done." And your approach seems to be the approach that I
take, given the tools that we have. But I really think its about tools
and not process. And I think that BDD is a lot more like what really
experienced TDD'ers do out of the gate. We're just choosing different
words and structures to make it easier to communicate across roles on
a team (customer, developer, tester, etc).



> Pat
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