[rspec-users] State Based vs. Behaviour Based Spec/Testing

Pat Maddox pergesu at gmail.com
Sun Mar 25 03:17:29 EDT 2007

On 3/25/07, Scott Taylor <mailing_lists at railsnewbie.com> wrote:
> On Mar 25, 2007, at 2:40 AM, Pat Maddox wrote:
> > On 3/25/07, Scott Taylor <mailing_lists at railsnewbie.com> wrote:
> >>
> >> On Mar 25, 2007, at 2:25 AM, Pat Maddox wrote:
> >>
> >>> On 3/24/07, Scott Taylor <mailing_lists at railsnewbie.com> wrote:
> >>>> 1.  Should you test protected and private methods in your specs?
> >>>
> >>> No.  You're specifying the behavior of an object as seen by the
> >>> outside world.  Of course protected and private methods aren't
> >>> available to the world, so why would you need to test them?  When
> >>> you're doing state-based testing, just call a method and then verify
> >>> that it returns the expected value or leaves your object in an
> >>> expected state.
> >>>
> >>
> >>
> >> How about if your writing code that is *only* meant to be reused?
> >> E.g., you are writing some class which is only meant to be derived
> >> from (ruby metaprogramming - Spec'ing rails would be a good example)?
> >>
> >
> > I'm not sure what you mean, to tell you the truth.  Would you mind
> > showing an example of some code that you want to spec but aren't sure
> > how?
> I had in mind a rails generic crud controller.  The basic gist of it
> is would be one class which had a series of private class methods.
> These methods could be called in any class which derived from this
> class, which would then set certain instance variables and instance
> methods for use in the class.
> A good example is a typical rails controller, or class:
> class Person < ActiveRecord::Base
>    has_many :posts
> end
> If you say something like:
> @person = Person.find(:first_name => "Scott", :last_name => "Taylor)
> @person.posts
> The first line will find the first person in the database that
> matches "Scott Taylor."  The second will find all posts associated
> with Scott Taylor.
> What do you think the ActiveRecord::Base class is going to look
> like?  It's going to have a private class method named "has_many"
> which excepts a string or symbol as a parameter.  This will then
> create an instance method in the derived class.  In this example,
> that instance method would "posts".  (For simplicity sake I've left
> out or changed some details of all the other things rails does).
> ActiveRecord::Base will never be used on its own, only as a class
> which is derived from.
> So how would ActiveRecord::Base be spec'ed out for this example?

I'm not sure how the Rails codebase is tested, but I think I'd do

base = ActiveRecord::Base.new
base.send :has_many, :posts

and verify from there.  I'm interested to see what David and Aslak think.


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