[rspec-users] simple == with prettier error messages + good documentation

[Nick Hoffman]

On 29/01/2009, at 2:18 PM, David Chelimsky wrote:
> On Thu, Jan 29, 2009 at 1:02 PM, aslak hellesoy <aslak.hellesoy at gmail.com 
> > wrote:
> On Thu, Jan 29, 2009 at 7:25 PM, David Chelimsky  
> <dchelimsky at gmail.com> wrote:
> >
> >
> > On Thu, Jan 29, 2009 at 12:00 PM, <r_j_h_box-sf at yahoo.com> wrote:
> >>
> >> Hi all,
> >>
> >> I've found myself writing a thing I think is less than optimal,  
> looking
> >> for suggestions.  The context is, I'm testing a result, and as a  
> part of
> >> that test, I might verify two or three things, which are  
> individually
> >> relevant but not really discrete results (?).
> >>
> >> Here's my thinking process, using a toy example:
> >>
> >>   foo.should == bar (or foo.should_not be_nil)
> >>
> >> > expected not to be nil, but was
> >>
> >> (hm, not very informative)
> >>
> >>   if( foo == nil )
> >>     "failure to setup foo".should == "foo should be set to the  
> thing that
> >> will be rendered"
> >>   end
> >>
> >> > expected "foo should be set to the thing that will be rendered",
> >> > got "failure to setup foo" (using ==)
> >>
> >> I've used this, by example, for a test on a dependency  
> (imagemagick),
> >> where if the dependency isn't found, I show a decent message with  
> info the
> >> tester can use to resolve it.  And, as I mentioned, I've used it  
> for
> >> revealing more details in cases where the it "" + the generic  
> error aren't
> >> informative.
> >>
> >> I'm satisfied using this method for things like detecting a  
> failure to use
> >> a test-helper correctly - works fine, doesn't get in my way as  
> part of the
> >> documentation.  Which brings me to the problem I'm concerned about:
> >>
> >> With this method, nothing come out in the generated spec-docs to  
> represent
> >> the thing I'm conditionally requiring.
> >>
> >> I guess I could get more fine-grained with my it()'s, but I've been
> >> preferring a more general statement for it(), that gives the  
> sense without
> >> the detail.
> >>
> >> Any suggestions?
> >
> > I can't think of anything that wouldn't result in something that  
> requires
> > more writing as of now. Maybe we need a new construct like:
> > it "does something" do
> >   with_message "this is a more specific message" do
> >     foo.should == bar
> >   end
> > end
> > WDYT?
> >
>
> I think that would be useful. Maybe make it more explicit that it's an
> error message:
>
> on_error "bla" do
>  ...
> end
>
> on_failure "..." do ????

I like "on_failure", as it's consistent with RSpec's output. Eg:
   31 examples, 0 failures

What could be done to make the construct more sentence-like? If used  
in this manner:

it 'should do something' do
   on_failure "@foo is nil" do
     @foo.should_not be_nil
   end
end

It reads like this to me:
   If "@foo is nil" fails, execute the block.

These are a bit verbose, but what do you think these approaches?:
http://gist.github.com/54726