testing behaviour or testing code?

[David Green]

hypothetical question for all you BDD experts:

I want to make sure that a :list action always returns widgets in alphabetical order. There's at least 2 ways of doing this:

it "should fetch items in alphabetical order" do
  Widget.should_receive(:find).with(:order => "name ASC")
  get :list
end

it "should fetch items in alphabetical order" do
  [:red, :green, :blue].each {|x| Widget.create(:name => x) }
  get :list
  assigns[:widgets].first.name.should == 'blue'
  assigns[:widgets].last.name.should == 'red'
end

with the first method, I get to mock the important calls and stub the rest, but the example is very closely tied to the implementation. If I change from Widget.find to Widget.find_alphabetically then the example breaks (assuming find_alphabetically() doesn't use AR::Base.find)

with the second method, I'm testing the behaviour more than how it's implemented. I don't care what the action does as long as it gives me an array of widgets sorted alphabetically, but I spend more time setting things up and worrying about model validations. In addition, the specs are tied to a db.

so which is the better method, and is there another way i havn't considered that gives me the best of both worlds?

[David Chelimsky-2]

On 8/24/07, David Green <justnothing@...> wrote:

>
> hypothetical question for all you BDD experts:
>
> I want to make sure that a :list action always returns widgets in
> alphabetical order. There's at least 2 ways of doing this:
>
> it "should fetch items in alphabetical order" do
>   Widget.should_receive(:find).with(:order => "name ASC")
>   get :list
> end
>
> it "should fetch items in alphabetical order" do
>   [:red, :green, :blue].each {|x| Widget.create(:name => x) }
>   get :list
>   assigns[:widgets].first.name.should == 'blue'
>   assigns[:widgets].last.name.should == 'red'
> end
>
> with the first method, I get to mock the important calls and stub the rest,
> but the example is very closely tied to the implementation. If I change from
> Widget.find to Widget.find_alphabetically then the example breaks (assuming
> find_alphabetically() doesn't use AR::Base.find)
>
> with the second method, I'm testing the behaviour more than how it's
> implemented. I don't care what the action does as long as it gives me an
> array of widgets sorted alphabetically, but I spend more time setting things
> up and worrying about model validations. In addition, the specs are tied to
> a db.
>
> so which is the better method, and is there another way i havn't considered
> that gives me the best of both worlds?

It depends on how high you have your magnifying glass set. Really!

Here's how I'd get there:

In an integration test, which I use as ... well ... integration tests
(i.e. pretty close to end to end - just no browser, so the javascript
can't get tested), I'd have something akin to the second example,
except that the creates would be done through a controller. This would
be in place before I ever started working on individual objects.

Then I'd develop the view, followed by the controller, followed by the
model. Typically, in my experience, that would result in something
like (not executing these so please pardon any potential bugs):

describe "/widgets/index" do
  it "should display a list of widgets" do
    assigns[:widgets] = [
      mock_model(Widget, :name => 'foo'),
      mock_model(Widget, :name => 'bar')
    ]
    render '/widgets/index'
    response.should have_tag('ul') do
      with_tag('li', 'foo')
      with_tag('li', 'bar')
    end
  end
end

describe WidgetController, 'responding to GET /widgets' do
  it "should assign a list of widgets" do
    Widget.should_receive(:find_alphabetically).and_return(list = [])
    get :index
    assigns[:widgets].should == []
  end
end

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?

David

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[Zach Dennis-2]

On 8/24/07, David Green <justnothing@...> wrote:

>
> hypothetical question for all you BDD experts:
>
> I want to make sure that a :list action always returns widgets in
> alphabetical order. There's at least 2 ways of doing this:
>
>
> it "should fetch items in alphabetical order" do
>   Widget.should_receive(:find).with(:order => "name ASC")
>   get :list
> end
>
> it "should fetch items in alphabetical order" do
>   [:red, :green, :blue].each {|x| Widget.create(:name => x) }
>   get :list
>   assigns[:widgets].first.name.should == 'blue'
>   assigns[:widgets].last.name.should == 'red'
> end
>
> with the first method, I get to mock the important calls and stub the rest,
> but the example is very closely tied to the implementation. If I change from
> Widget.find to Widget.find_alphabetically then the example breaks (assuming
> find_alphabetically() doesn't use AR::Base.find)
>
> with the second method, I'm testing the behaviour more than how it's
> implemented. I don't care what the action does as long as it gives me an
> array of widgets sorted alphabetically, but I spend more time setting things
> up and worrying about model validations. In addition, the specs are tied to
> a db.
>
> so which is the better method, and is there another way i havn't considered
> that gives me the best of both worlds?

In your controller have something like:

    @widgets = mock("widgets")
    Widget.should_receive(:find_alphabetically).and_return(@widgets)
    get :index

You don't care in your controller test what actually gets returned,
just that it's calling the right method on the model. Now in your
"Widget" spec have one that looks like:

    describe Widget, "#find_alphabetically) do
         before do
             Widget.destroy_all
             # create some widgets for your test, say widgets C, A, B
in that order
             @results = Widget.find_alphabetically
         end

         it "has widget A as the first widget" do
             # ...
         end

         it "has widget B as the second widget" do
             # ...
         end

         it "has widget C as the third widget" do
             # ...
         end
    end

HTH,

Zach
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[Pat Maddox]

On 8/24/07, David Chelimsky <dchelimsky@...> 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.

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.

Pat
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[David Chelimsky-2]

On 8/24/07, Pat Maddox <pergesu@...> wrote:

> On 8/24/07, David Chelimsky <dchelimsky@...> 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).

>
> Pat
> _______________________________________________
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[Pat Maddox]

On 8/24/07, David Chelimsky <dchelimsky@...> wrote:

> On 8/24/07, Pat Maddox <pergesu@...> wrote:
> > On 8/24/07, David Chelimsky <dchelimsky@...> 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.

You're absolutely right, there should be an integration or acceptance
test that exercises the behavior.  I would question then whether or
not the example for find_alphabetically is (a) pulling its weight or
(b) too brittle.

(a) What value does the example provide?  It doesn't serve to document
how find_alphabetically is used (usage doco is provided by good
naming, and secondarily by the controller specs).  It doesn't give you
any information that you couldn't get by looking at the
implementation, because it duplicates the implementation exactly.  So
the only real benefits of it is that you can see it when you visually
scan the specs, and it shows up in the output when you generate spec
docs.

Those are real benefits, of course, which leads me to believe that the
spec is just a bit brittle.  Knowing what exact arguments are passed
to Widget.find doesn't add any value.  It makes the test more
cluttered and brittle.  All we really care about is that a find is
performed.  In that case, perhaps the example should be simply

it "should provide a list of widgets sorted alphabetically" do
  Widget.should_receive(:find)
  Widget.find_alphabetically
end

WDYT?

> 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).

Will Story Runner give us all the same abilities as Rails ITs,
obviating the need for test::unit altogether?

Pat
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[David Chelimsky-2]

On 8/24/07, Pat Maddox <pergesu@...> wrote:

> On 8/24/07, David Chelimsky <dchelimsky@...> wrote:
> > On 8/24/07, Pat Maddox <pergesu@...> wrote:
> > > On 8/24/07, David Chelimsky <dchelimsky@...> 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.
>
> You're absolutely right, there should be an integration or acceptance
> test that exercises the behavior.  I would question then whether or
> not the example for find_alphabetically is (a) pulling its weight or
> (b) too brittle.
>
> (a) What value does the example provide?  It doesn't serve to document
> how find_alphabetically is used (usage doco is provided by good
> naming, and secondarily by the controller specs).  It doesn't give you
> any information that you couldn't get by looking at the
> implementation, because it duplicates the implementation exactly.  So
> the only real benefits of it is that you can see it when you visually
> scan the specs, and it shows up in the output when you generate spec
> docs.
>
> Those are real benefits, of course, which leads me to believe that the
> spec is just a bit brittle.  Knowing what exact arguments are passed
> to Widget.find doesn't add any value.  It makes the test more
> cluttered and brittle.  All we really care about is that a find is
> performed.  In that case, perhaps the example should be simply
>
> it "should provide a list of widgets sorted alphabetically" do
>   Widget.should_receive(:find)
>   Widget.find_alphabetically
> end
>
> WDYT?

The problem w/ that, for me, is that if I change that method for any
reason I won't know if I broke anything until I run the integration
tests. I'll trade off a bit of brittleness for rapid feedback. Not
always - but usually.

>
> > 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).
>
> Will Story Runner give us all the same abilities as Rails ITs,
> obviating the need for test::unit altogether?

Yes. Just need to figure out how to wrap IT w/ Story Runner.

Cheers,
David

>
> Pat
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[David Green]

David Chelimsky-2 wrote:

It depends on how high you have your magnifying glass set. Really!

Here's how I'd get there:

In an integration test, which I use as ... well ... integration tests
(i.e. pretty close to end to end - just no browser, so the javascript
can't get tested), I'd have something akin to the second example,
except that the creates would be done through a controller. This would
be in place before I ever started working on individual objects.

Then I'd develop the view, followed by the controller, followed by the
model. Typically, in my experience, that would result in something
like (not executing these so please pardon any potential bugs):

describe "/widgets/index" do
  it "should display a list of widgets" do
    assigns[:widgets] = [
      mock_model(Widget, :name => 'foo'),
      mock_model(Widget, :name => 'bar')
    ]
    render '/widgets/index'
    response.should have_tag('ul') do
      with_tag('li', 'foo')
      with_tag('li', 'bar')
    end
  end
end

describe WidgetController, 'responding to GET /widgets' do
  it "should assign a list of widgets" do
    Widget.should_receive(:find_alphabetically).and_return(list = [])
    get :index
    assigns[:widgets].should == []
  end
end

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?

David

after reading your post yesterday, I dug out some old specs that were doing some really complex setup using real objects, and rewrote them to exclusively use mocks and stubs. The specs run around 20% quicker, but more importantly, the code is much less complex and much easier to work with! it's a relief not having to worry about model behaviour in controller specs. so much so that I ended up adding around 50% more examples and catching some bugs which I'd missed.

I wasn't testing my views at all, instead relying on integrate_views to catch any problems. This time round I wrote view specs, which is a little more work but testing only one MVC aspect in isolation really makes things simpler. I realise now that the old way, I was using controller specs to test integration rather than controllers.

I'm relatively new to programming, and it's all self taught so I can't speak with authority, but the more I use BDD, the more I like it. It just makes sense.  thanks for your help

p.s. when is the book coming? :)

[Hans de Graaff]

On Sat, 2007-08-25 at 00:01 -0700, David Green wrote:

> I wasn't testing my views at all, instead relying on integrate_views to
> catch any problems. This time round I wrote view specs, which is a little
> more work but testing only one MVC aspect in isolation really makes things
> simpler. I realise now that the old way, I was using controller specs to
> test integration rather than controllers.

I'm actually doing a bit of both. I write all my controller specs
without integrate_views, with separate specs for the views. On top of
that I'm also including very simple specs for each action in the
controller including views and relying on fixtures, mostly like this:

it 'should be a valid page' do
  get :index
  response.should be_xhtml
end

Even though all the behaviour is tested without views and fixtures, this
additional check helps to find problems in the interaction between
views, controller, and model, and it is the only way I know to validate
the pages as XHTML.

Kind regards,

Hans


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[Pat Maddox]

On 8/24/07, David Chelimsky <dchelimsky@...> wrote:

> On 8/24/07, Pat Maddox <pergesu@...> wrote:
> > On 8/24/07, David Chelimsky <dchelimsky@...> 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.

Pat
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[David Chelimsky-2]

On 9/2/07, Pat Maddox <pergesu@...> wrote:

> On 8/24/07, David Chelimsky <dchelimsky@...> wrote:
> > On 8/24/07, Pat Maddox <pergesu@...> wrote:
> > > On 8/24/07, David Chelimsky <dchelimsky@...> 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
born.

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:

  model.getName()

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).

FWIW.

Cheers,
David

>
> Pat
> _______________________________________________
> rspec-users mailing list
> rspec-users@...
> http://rubyforge.org/mailman/listinfo/rspec-users
>
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[Pat Maddox]

On 9/2/07, David Chelimsky <dchelimsky@...> wrote:

> On 9/2/07, Pat Maddox <pergesu@...> wrote:
> > On 8/24/07, David Chelimsky <dchelimsky@...> wrote:
> > > On 8/24/07, Pat Maddox <pergesu@...> wrote:
> > > > On 8/24/07, David Chelimsky <dchelimsky@...> 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
> born.
>
> 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.

Hi David,

Thanks so much for your thoughtful reply.

You're right, and I didn't mean to suggest that mock objects were a
BDD concept at all.  However it seems to me that BDDers embrace mock
objects as a very useful design tool, whereas classical TDDers would
use them sparsely, when a resource is expensive or difficult to use
directly.  For example, Beck talks about mocking a database in his
book, and that's that.  Astels demonstrates mocking the roll of a die.
 He does briefly use mocks before he's ready to implement the GUI part
of the app.

Those are the two TDD books with which I'm most familiar.  I'm sure a
lot has changed in the TDD community since then, and indeed you can
see that Astels' mentality has changed somewhat.  His "one assertion
per test" article [1] parses an address and then verifies it by
asserting the getters.  His remake, "one expectation per example" [2]
is a bit different in that he passes a mocked builder in and uses that
to verify that the parsing code works, exposing no getters at all.
That to me signifies a fundamental shift in TDD thought.  Instead of
thinking about objects in isolation and what services they provide, we
think of the services an object provides and how it interacts with
other objects and uses their services.

I'm certain that it's not a new way of thinking, but hopefully you can
see why I'd believe it's probably not mainstream.

There's one other roadblock to my thinking, and it results from using
RSpec almost exclusively within Rails projects.  I think it's obvious
why you mock models when writing view and controller specs.  However
less obvious to me is why mock associations in model specs, and I
think it has to do with the fact that AR couples business and
persistence logic.

If we just had domain objects that never hit a database, then we might
initially mock interactions but then use concrete instances when we
later implemented those classes.  When I think of Beck's Money
example, or Martin Fowler's video rental list in Refactoring, it seems
silly to me to use mocks in those cases.  Perhaps you might at the
very beginning, but you'd sub real objects in as you implemented them.
 We don't do this with AR because they're simply too heavy.

This culminates in another general idea I've had which is to mock
services in a lower layer, and use concrete instances for objects in
the same layer when possible.  If we were to split AR into domain
objects and a data access layer, the domain objects would mock calls
to the data access layer but use concrete domain objects in the tests.
 The unit tests remain fast and simple, and mocks no longer get in the
way of refactoring.

Of course then you're writing integration tests at a fairly low level
I guess, but that's 100% acceptable to me in the interest of getting
stuff done rather than being dogmatic.

> 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:
>
>   model.getName()
>
> 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.

Agreed.  I guess for me it's easier to get the production code right
and then fix the tests after the fact.  I'd hate to do all the work of
changing the production and test code and then find out it was
incorrect.  Fixing tests after fixing the production code amounts to
the same work as doing it all in one step, because as you mentioned
it's essentially a manual process.

> 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).

So "ideally," who would write Story Runner stories?  I put it in
quotes because I think it would differ greatly depending on the work
environment, what kind of level of interaction you have with the
customer, etc.  Using TDD terms, would we consider SR stories to be
Customer or Developer tests?  I gather from your insight that they're
Customer tests.

Finally I agree 100% on not focusing on process.  I'm trying to figure
out the most effective process given the tools currently available,
and will be constantly changing it as more/better tools come along.
Although I suppose what I should really be spending my energy on is
building the tools that will make all our lives better ;)

Pat
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[Rodrigo Alvarez Fernández]

I have an article about this in my blog, with a controller spec example, testing just behaviour and not the code. Please, comment it and tell me what you think. I guess that with the new Story runner, this approach will be even better.

Thanks in advance.

--
http://papipo.blogspot.com

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[David Chelimsky-2]

On 9/2/07, Rodrigo Alvarez Fernández <papipo@...> wrote:
> I have an article about this in my blog, with a controller spec example,
> testing just behaviour and not the code. Please, comment it and tell me what
> you think.

I added comments on the blog:
http://papipo.blogspot.com/2007/08/bdd-isolation-integration.html

> I guess that with the new Story runner, this approach will be
> even better.

Be careful here - Story Runner is not really intended to solve these
lower level problems. Not that it can't be used for that, but it's a
lot more heavyweight and better suited for high level scenarios that
exercise the code end to end (including the DB).

Cheers,
David

>
> Thanks in advance.
>
> --
> http://papipo.blogspot.com
>
> _______________________________________________
> rspec-users mailing list
> rspec-users@...
> http://rubyforge.org/mailman/listinfo/rspec-users
>

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[Rodrigo Alvarez Fernández]

On 9/2/07, David Chelimsky <dchelimsky@...> wrote:

On 9/2/07, Rodrigo Alvarez Fernández <papipo@...> wrote:
> I have an article about this in my blog, with a controller spec example,
> testing just behaviour and not the code. Please, comment it and tell me what
> you think.

I added comments on the blog:
http://papipo.blogspot.com/2007/08/bdd-isolation-integration.html

> I guess that with the new Story runner, this approach will be
> even better.

Be careful here - Story Runner is not really intended to solve these
lower level problems. Not that it can't be used for that, but it's a
lot more heavyweight and better suited for high level scenarios that
exercise the code end to end (including the DB).

Yes, I meant as integration tests. 

Cheers,
David

>
> Thanks in advance.
>
> --
> http://papipo.blogspot.com
>
> _______________________________________________
> rspec-users mailing list
> rspec-users@...
> http://rubyforge.org/mailman/listinfo/rspec-users
>

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[David Chelimsky-2]

On 9/2/07, Pat Maddox <pergesu@...> wrote:

> On 9/2/07, David Chelimsky <dchelimsky@...> wrote:
> > On 9/2/07, Pat Maddox <pergesu@...> wrote:
> > > On 8/24/07, David Chelimsky <dchelimsky@...> wrote:
> > > > On 8/24/07, Pat Maddox <pergesu@...> wrote:
> > > > > On 8/24/07, David Chelimsky <dchelimsky@...> 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
> > born.
> >
> > 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.
>
> Hi David,
>
> Thanks so much for your thoughtful reply.

Thanks for your thought provoking post!

> You're right, and I didn't mean to suggest that mock objects were a
> BDD concept at all.  However it seems to me that BDDers embrace mock
> objects as a very useful design tool, whereas classical TDDers would
> use them sparsely, when a resource is expensive or difficult to use
> directly.

This is true to some extent, but the mock objects paper, which
introduced the idea of mocks-as-design-tool
(http://mockobjects.com/files/mockrolesnotobjects.pdf) was presented
at OOPSLA 04, and the thinking that it came from had already been
evolving.

> For example, Beck talks about mocking a database in his
> book, and that's that.  Astels demonstrates mocking the roll of a die.
> He does briefly use mocks before he's ready to implement the GUI part
> of the app.
>
> Those are the two TDD books with which I'm most familiar.  I'm sure a
> lot has changed in the TDD community since then, and indeed you can
> see that Astels' mentality has changed somewhat.  His "one assertion
> per test" article [1] parses an address and then verifies it by
> asserting the getters.  His remake, "one expectation per example" [2]
> is a bit different in that he passes a mocked builder in and uses that
> to verify that the parsing code works, exposing no getters at all.
> That to me signifies a fundamental shift in TDD thought.  Instead of
> thinking about objects in isolation and what services they provide, we
> think of the services an object provides and how it interacts with
> other objects and uses their services.
>
> I'm certain that it's not a new way of thinking, but hopefully you can
> see why I'd believe it's probably not mainstream.
>
> There's one other roadblock to my thinking, and it results from using
> RSpec almost exclusively within Rails projects.  I think it's obvious
> why you mock models when writing view and controller specs.  However
> less obvious to me is why mock associations in model specs, and I
> think it has to do with the fact that AR couples business and
> persistence logic.

Absolutely! AR presents quite a testing conundrum. It's clear from the
testing approach supported by Rails directly that decoupling from the
database is simply not of interested to DHH and company. Or at least
it wasn't early on. I see mock frameworks starting to appear in the
Rails codebase, so perhaps this is changing. And I don't mean to
suggest that the Rails core team approach is the wrong approach. It
simply does not align with what you've called "classical TDD
thinking".

> If we just had domain objects that never hit a database, then we might
> initially mock interactions but then use concrete instances when we
> later implemented those classes.  When I think of Beck's Money
> example, or Martin Fowler's video rental list in Refactoring, it seems
> silly to me to use mocks in those cases.

I think you're right. Even if you're going down what I view as the
ideal mockists path - mocking everything that you need that doesn't
exist yet - I've often used mocks in process, but replaced them w/ the
real deal once the real objects existed. Then you're really using
mocks for what they're most powerful at: interface discovery. And then
disposing of them once they've passed their usefulness in a given
situation.

In the case of AR, I keep them around to keep from hitting the DB.

> Perhaps you might at the
> very beginning, but you'd sub real objects in as you implemented them.

D'oh! You ARE an ideal mockist!

>  We don't do this with AR because they're simply too heavy.

Funny - I'm tempted to remove what I wrote above - but this is fun -
responding as I go and then discovering that you already made the same
point.

> This culminates in another general idea I've had which is to mock
> services in a lower layer, and use concrete instances for objects in
> the same layer when possible.  If we were to split AR into domain
> objects and a data access layer, the domain objects would mock calls
> to the data access layer but use concrete domain objects in the tests.
>  The unit tests remain fast and simple, and mocks no longer get in the
> way of refactoring.

Ay, there's the rub.

The problem we face is that AR promises huge productivity gains for
the non TDD-er, and challenges the thinking of the die-hard TDD-er.

I've gone back and forth about whether it's OK to test validations like this:

it "should validate_presence_of digits" do
  PhoneNumber.expects(:validates_presence_of).with(:digits)
  load "#{RAILS_ROOT}/app/models/phone_number.rb"
end

On the one hand, it looks immediately like we're testing
implementation. On the other, we're not really - we're mocking a call
to an API. The confusion is that the API is represented in the same
object as the one we're testing (at least its class object). I haven't
really done this in anger yet, but I'm starting to think it's the
right way to go - especially now that we have Story Runner to cover
things end to end. WDYT of this approach?

>
> Of course then you're writing integration tests at a fairly low level
> I guess, but that's 100% acceptable to me in the interest of getting
> stuff done rather than being dogmatic.

+ 1 - in the end this is all about getting stuff done and knowing WHEN
you're done.

> > 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:
> >
> >   model.getName()
> >
> > 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.
>
> Agreed.  I guess for me it's easier to get the production code right
> and then fix the tests after the fact.  I'd hate to do all the work of
> changing the production and test code and then find out it was
> incorrect.  Fixing tests after fixing the production code amounts to
> the same work as doing it all in one step, because as you mentioned
> it's essentially a manual process.
>
> > 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).
>
> So "ideally," who would write Story Runner stories?  I put it in
> quotes because I think it would differ greatly depending on the work
> environment, what kind of level of interaction you have with the
> customer, etc.  Using TDD terms, would we consider SR stories to be
> Customer or Developer tests?  I gather from your insight that they're
> Customer tests.

Yes - in my view they are Customer Tests - but bear in mind that that
means "tests created by the person acting in the customer role." On a
team of one, that might be the same person as the developer.

> Finally I agree 100% on not focusing on process.  I'm trying to figure
> out the most effective process given the tools currently available,
> and will be constantly changing it as more/better tools come along.
> Although I suppose what I should really be spending my energy on is
> building the tools that will make all our lives better ;)

Patches always welcome!

Cheers Pat.

David

>
> Pat
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>
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[Jay Levitt-7]

On 9/2/2007 12:43 PM, David Chelimsky wrote:

> The problem we face is that AR promises huge productivity gains for
> the non TDD-er, and challenges the thinking of the die-hard TDD-er.
>
> I've gone back and forth about whether it's OK to test validations like this:
>
> it "should validate_presence_of digits" do
>   PhoneNumber.expects(:validates_presence_of).with(:digits)
>   load "#{RAILS_ROOT}/app/models/phone_number.rb"
> end
>
> On the one hand, it looks immediately like we're testing
> implementation. On the other, we're not really - we're mocking a call
> to an API. The confusion is that the API is represented in the same
> object as the one we're testing (at least its class object). I haven't
> really done this in anger yet, but I'm starting to think it's the
> right way to go - especially now that we have Story Runner to cover
> things end to end. WDYT of this approach?

Personally, I don't much like it.  It feels too much like:

it "should validate_presence_of digits" do
   my_model.line(7).should_read "validates_presence_of :digits"
end

I can write specs like that all day and ensure absolutely nothing about
my code.

I like to think of specs as a form of N-version programming where N=2
(or maybe N=3 now with Story Runner).  By using a different vocabulary
to express the specs than the actual code, we are more likely to think
of the problem differently, and thus find places where the two versions
of our code differ.  Sometimes, it means we miswrote the spec;
sometimes, it means we miswrote the code.

But if all your spec does is guarantee that your code reads a certain
way, you've done nothing but protect against accidental edits.  And if
you're gonna go that way, why not go all the way:

it "shouldn't change unless I change the spec too" do
   MD5.new(my_model).should == "0xDEADBEEF0FFD2FFE4..."
end

I'd much rather see:

it "should prevent me from entering anything but digits" do
   PhoneNumber.new("800-MATTRESS").should_not be_valid
end

And then, every time I find an edge case, I add another spec:

it "should allow me to enter dashes" do
   PhoneNumber.new("800-555-1212").should be_valid
end

it "should only allow 10 digits" do
   PhoneNumber.new("800-555-12121212").should_not be_valid
end

etc.


Jay Levitt

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[David Chelimsky-2]

On 9/2/07, Jay Levitt <lists-rspec@...> wrote:

> On 9/2/2007 12:43 PM, David Chelimsky wrote:
> > The problem we face is that AR promises huge productivity gains for
> > the non TDD-er, and challenges the thinking of the die-hard TDD-er.
> >
> > I've gone back and forth about whether it's OK to test validations like this:
> >
> > it "should validate_presence_of digits" do
> >   PhoneNumber.expects(:validates_presence_of).with(:digits)
> >   load "#{RAILS_ROOT}/app/models/phone_number.rb"
> > end
> >
> > On the one hand, it looks immediately like we're testing
> > implementation. On the other, we're not really - we're mocking a call
> > to an API. The confusion is that the API is represented in the same
> > object as the one we're testing (at least its class object). I haven't
> > really done this in anger yet, but I'm starting to think it's the
> > right way to go - especially now that we have Story Runner to cover
> > things end to end. WDYT of this approach?
>
> Personally, I don't much like it.  It feels too much like:
>
> it "should validate_presence_of digits" do
>    my_model.line(7).should_read "validates_presence_of :digits"
> end
>
> I can write specs like that all day and ensure absolutely nothing about
> my code.
>
> I like to think of specs as a form of N-version programming where N=2
> (or maybe N=3 now with Story Runner).  By using a different vocabulary
> to express the specs than the actual code, we are more likely to think
> of the problem differently, and thus find places where the two versions
> of our code differ.  Sometimes, it means we miswrote the spec;
> sometimes, it means we miswrote the code.
>
> But if all your spec does is guarantee that your code reads a certain
> way, you've done nothing but protect against accidental edits.  And if
> you're gonna go that way, why not go all the way:
>
> it "shouldn't change unless I change the spec too" do
>    MD5.new(my_model).should == "0xDEADBEEF0FFD2FFE4..."
> end
>
> I'd much rather see:
>
> it "should prevent me from entering anything but digits" do
>    PhoneNumber.new("800-MATTRESS").should_not be_valid
> end
>
> And then, every time I find an edge case, I add another spec:
>
> it "should allow me to enter dashes" do
>    PhoneNumber.new("800-555-1212").should be_valid
> end
>
> it "should only allow 10 digits" do
>    PhoneNumber.new("800-555-12121212").should_not be_valid
> end

A couple of things to consider:

There's a very useful guideline in TDD that says "test YOUR code, not
everyone elses." The validation library we're testing here is
ActiveRecord's. It's already tested (we hope!).

Also - there's a difference between the behaviour of a system and the
behaviour of an object. The system's job is to validate that the phone
number is all digits. So it makes sense to have examples like that in
high level examples using Story Runner, rails integration tests, or an
in-browser suite like Selenium or Watir.

This model object's job is to make sure the input gets validated, not
to actually validate it. If the model made a more OO-feeling call out
to a message library - something like this:

class PhoneNumber
  def validators
    @validators ||= []
  end

  def add_validator (validator)
    validators << validator
  end

  def validate(input)
    validators.each {|v| v.validate (input)}
  end
end

Then submitting mock validators via add_validator and setting mock
expectations that they get called would be totally par for the course.

In AR, the validators are added declaratively. This is a Rails design
decision that we have to either live with or write other code around.
Choosing to live with it, it seems to me that mocking the call to
validates_presence_of :digits is no different than mocking validate on
an injected validator.

That all make sense?

>
> etc.
>
>
> Jay Levitt
>
> _______________________________________________
> rspec-users mailing list
> rspec-users@...
> http://rubyforge.org/mailman/listinfo/rspec-users
>

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[Pat Maddox]

On 9/2/07, David Chelimsky <dchelimsky@...> wrote:

> On 9/2/07, Jay Levitt <lists-rspec@...> wrote:
> > On 9/2/2007 12:43 PM, David Chelimsky wrote:
> > > The problem we face is that AR promises huge productivity gains for
> > > the non TDD-er, and challenges the thinking of the die-hard TDD-er.
> > >
> > > I've gone back and forth about whether it's OK to test validations like this:
> > >
> > > it "should validate_presence_of digits" do
> > >   PhoneNumber.expects(:validates_presence_of).with(:digits)
> > >   load "#{RAILS_ROOT}/app/models/phone_number.rb"
> > > end
> > >
> > > On the one hand, it looks immediately like we're testing
> > > implementation. On the other, we're not really - we're mocking a call
> > > to an API. The confusion is that the API is represented in the same
> > > object as the one we're testing (at least its class object). I haven't
> > > really done this in anger yet, but I'm starting to think it's the
> > > right way to go - especially now that we have Story Runner to cover
> > > things end to end. WDYT of this approach?
> >
> > Personally, I don't much like it.  It feels too much like:
> >
> > it "should validate_presence_of digits" do
> >    my_model.line(7).should_read "validates_presence_of :digits"
> > end
> >
> > I can write specs like that all day and ensure absolutely nothing about
> > my code.
> >
> > I like to think of specs as a form of N-version programming where N=2
> > (or maybe N=3 now with Story Runner).  By using a different vocabulary
> > to express the specs than the actual code, we are more likely to think
> > of the problem differently, and thus find places where the two versions
> > of our code differ.  Sometimes, it means we miswrote the spec;
> > sometimes, it means we miswrote the code.
> >
> > But if all your spec does is guarantee that your code reads a certain
> > way, you've done nothing but protect against accidental edits.  And if
> > you're gonna go that way, why not go all the way:
> >
> > it "shouldn't change unless I change the spec too" do
> >    MD5.new(my_model).should == "0xDEADBEEF0FFD2FFE4..."
> > end
> >
> > I'd much rather see:
> >
> > it "should prevent me from entering anything but digits" do
> >    PhoneNumber.new("800-MATTRESS").should_not be_valid
> > end
> >
> > And then, every time I find an edge case, I add another spec:
> >
> > it "should allow me to enter dashes" do
> >    PhoneNumber.new("800-555-1212").should be_valid
> > end
> >
> > it "should only allow 10 digits" do
> >    PhoneNumber.new("800-555-12121212").should_not be_valid
> > end
>
> A couple of things to consider:
>
> There's a very useful guideline in TDD that says "test YOUR code, not
> everyone elses." The validation library we're testing here is
> ActiveRecord's. It's already tested (we hope!).
>
> Also - there's a difference between the behaviour of a system and the
> behaviour of an object. The system's job is to validate that the phone
> number is all digits. So it makes sense to have examples like that in
> high level examples using Story Runner, rails integration tests, or an
> in-browser suite like Selenium or Watir.
>
> This model object's job is to make sure the input gets validated, not
> to actually validate it. If the model made a more OO-feeling call out
> to a message library - something like this:
>
> class PhoneNumber
>   def validators
>     @validators ||= []
>   end
>
>   def add_validator (validator)
>     validators << validator
>   end
>
>   def validate(input)
>     validators.each {|v| v.validate (input)}
>   end
> end
>
> Then submitting mock validators via add_validator and setting mock
> expectations that they get called would be totally par for the course.
>
> In AR, the validators are added declaratively. This is a Rails design
> decision that we have to either live with or write other code around.
> Choosing to live with it, it seems to me that mocking the call to
> validates_presence_of :digits is no different than mocking validate on
> an injected validator.
>
> That all make sense?

There's nothing technically *wrong* with it, and logically it holds weight.

It just doesn't feel right.

Your key point is that we're making an API call, which I agree with.
We also agree that AR probably does too much, and I think this is a
situation where we should go with the flow.  We call my_record.valid?
and end up with my_record.errors if it's not valid.  An AR object is
in fact responsible for its own validation (even if you feel it's too
much responsibility).  It makes sense to specify the object's behavior
in the same way.

Personally I can't find a strong argument either way.  I'm sure it's a
matter of taste here.  I would prefer to look at a spec and get as
much info on how to use an object as possible.  In that case, creating
an object, calling valid?, and inspecting errors is probably more
helpful.  But after giving this a lot of thought, I'm not sure it
warrants a ton of thought :)

Pat
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[Peter Marklund-2]

> There's a very useful guideline in TDD that says "test YOUR code, not
> everyone elses." The validation library we're testing here is
> ActiveRecord's. It's already tested (we hope!).

Personally, I don't have the courage to assume Rails code is always  
working. I know from experience it doesn't always work although it is  
quite solid in general. The Rails code has been tested but not in  
conjunction with my particular apps. I also want to test my  
assumptions of how the Rails API works, maybe it doesn't work as I  
think. Having tests/specs that cover Rails interaction with my app,  
which higher level tests of course naturally do (system/integration  
tests), gives me much more courage to upgrade Rails as well.

Peter

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