[rspec-users] Spec'ing via features
ben at benmabey.com
Tue Nov 25 12:26:41 EST 2008
David Chelimsky wrote:
> On Tue, Nov 25, 2008 at 12:52 AM, Ben Mabey <ben at benmabey.com> wrote:
>> Andrew Premdas wrote:
>>> I came across this idea of dropping unit tests for acceptance tests in
>>> the java world. It didn't like it there and I don't like it here, but
>>> maybe thats because I'm an old fuddy duddy or something :). I do think
>>> that every public method of an object should be specifically unit
>>> tested, and yes that means that if you refactor your object you should
>>> refactor your unit tests. This isn't really that much of a burden if
>>> you design your objects to have simple and minimal public api's in the
>>> first place.
>>> What is that makes you think you can refactor code run acceptance
>>> tests and be save without unit tests? Writing tests "that guarantee
>>> the correct functioning of the system" isn't something you can just
>>> do. Best you can hope for with acceptance tests is that part of the
>>> system functions correctly most of the time in some circumstances.
>>> Perhaps its the BDD ideal that your only writing the code you need to
>>> make your acceptance tests pass, that make you think your acceptance
>>> tests cover all your code. However just because you've written minimal
>>> code to make an acceptance test pass doesn't mean that you can't use
>>> this code in a multitude of different ways
>>> Do you really think that BDD created code is just some black box that
>>> you can tinker around with restructure and still be sure it works just
>>> because your black box tests still work?
>>> I just don't believe you can get the coverage you need for an
>>> application using acceptance testing / features alone. If you do
>>> actually write enough features to do this you'll end up doing much
>>> more work than writing unit tests combined with features.
>> +1 again.
>>> All best
>> Here is how I look at the two sets of tests...
>> Features at the application level (acceptance tests) instill more confidence
> That and, as Kent Beck describes today, responsible software, are why
> we do testing at all.
>> in me about the correctness of the system's behavior. Object level code
>> examples (unit tests) instill more confidence in me about the design of the
>> With acceptance tests passing we have no guarantee about the state of the
>> design. Remember, TDD/BDD naturally produces easy to test objects and by
>> skipping object level examples you run the risk of creating dependent laden,
>> highly coupled objects that are hard to test. (Just think, you can make all
>> of your features, for a web app, pass by writing the app in PHP4 with no
>> objects at all :p .)
> Which is not an inherently bad deal, if that's your comfort zone, and
> if that's the comfort zone of *everybody* on your team.
>> I also think that acceptance tests are too slow to be used in all
>> refactorings and they are not fine grained enough so you'll end up doing
>> more debugging than you would otherwise with good object level coverage. I
>> generally try to keep each individual unit test faster than a tenth of a
>> second, as suggested in 'Working Effectively With Legacy Code'. What
>> results is an extremely fast suite that can be used to quickly do
>> refactorings. I have experienced the pain of using just Cucumber features
>> first hand-- finding bugs on this level is just not as fast object level
>> examples. If you skip object level examples you are incurring a technical
>> debt that you will feel down the road, IMO.
>> Someone at the start of this thread had wondered what people had learned
>> when they went through this process of balancing FIT tests with unit tests.
> I can speak to this a bit. Maybe more than a bit.
> When I was working with .NET FitNesse and NUnit, we had very high
> levels of coverage in NUnit. Early on one project I told Micah Martin
> (who co-created FitNesse with Bob Martin) that I was concerned about
> the duplication between our FitNesse tests and NUnit tests and
> questioned the value of keeping it.
> Micah pointed out reasons that made absolute 100% perfect sense in the
> context of the project we were working on. The customers were
> encouraged to own the FitNesse tests. They were stored on a file
> system, backed up in zip files, while the NUnit tests were stored in
> subversion with the code. The FitNesse fixtures were stored with the
> application code, distant from the FitNesse tests.
> In order to foster confidence in the code amongst the developers,
> having a high level of coverage in NUnit made sense, in spite of the
> duplication with some of the FitNesse tests.
> That duplication, by the way, was only in terms of method calls at the
> highest levels of the system. When a FitNesse test made an API call,
> that message went all the way to the database and back.
> When an NUnit test made the same call, that message typically got no
> further than the object in the test, using stubs and mocks to keep it
> Now fast forward to our current discussion about Cucumber and RSpec.
> As things stand today, we tend to store .feature files right in the
> app alongside the step_definitions and the application code.
> The implications here are different from having a completely decoupled
> acceptance testing system. I'm not saying that abandoning RSpec or
> Test::Unit or whatever is the right thing to do. But I certainly feel
> less concerned about removing granular code examples, especially on
> rails/merb controllers and views, when I've got excellent coverage of
> them from Cucumber with Webrat. Thus far I have seen a case where I
> couldn't quickly understand a failure in a view or controller based on
> the feedback I get from Cucumber with Webrat.
> But this is mostly because that combination of tools does a very good
> job of pointing me to the right place. This is not always the case
> with high level examples. If you're considering relaxing a requirement
> for granular examples, you should really consider each case separately
> and include the level of granularity of feedback you're going to get
> from your toolset when you make that decision.
> Now this is how *I* see things.
> For anybody who is brand new to all this, my feeling is that whatever
> pain there is from duplication between the two levels of examples and
> having to change granular examples to refactor is eclipsed by the pain
> of debugging from high level examples.
> Also, as I alluded to earlier, every team is different. If you are
> working solo, the implications of taking risks by working
> predominantly at higher levels is different from when you are on a
> team. The point of testing is not to follow a specific process. The
> point is to instill confidence so you can continue to work without
> migraines, and deliver quality software.
Thanks for sharing your experience and insight! Having never used
FitNesse I didn't see that distinction at all. What you said makes a lot
>> While I know some people on this list could provide some first hand
>> experience, I think this post by Bob Martin should provide some good
>> - Ben Mabey
>>> 2008/11/25 Raimond Garcia <lists at ruby-forum.com>:
>>>>> Wow, if that's it in a nutshell... :)
>>>> Thanks Pat, great summary.
>>>> I have to admit that I'm as crazy as Yehuda,
>>>> and believe that all we need are just acceptance tests,
>>>> at different layers of abstraction, for clients and developers.
>>>> I also see the benefits of speccing out single object's behaviors, with
>>>> the aim of a good design.
>>>> However, the drawbacks of doing this out-weight the benefits, in my
>>>> Testing how every method of an object is going to behave,
>>>> implies that after refactoring, that spec will no longer be useful,
>>>> eventhough the business and application logic stay the same.
>>>> I believe that being able to come up with a good design,
>>>> is not only dependent on writing tests before your implementation,
>>>> but also on knowing how to write a good implementation.
>>>> This can be gained through experience,
>>>> reading books, blogs, pair-programming,
>>>> using tools to tell you about the complexity of your code,
>>>> and a constant process of refactoring as we complete requirements,
>>>> and then fully understand what the best design could be.
>>>> Therefore in my opinion, by writing tests that guarantee
>>>> the correct functioning of the system, we have a robust suite of tests.
>>>> Let the refactoring come storming in and change the whole
>>>> but the tests should not be affected at all,
>>>> as I'm not testing my implementation nor design,
>>>> only the correct functioning of the system,
>>>> and relying on other tools on top of tests to maintain my code
>>>> nice, clean and understandable by anyone that comes along.
>>>> Kind Regards,
>>>> Posted via http://www.ruby-forum.com/.
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