rspec users - Apr 2011 - Need suggestions on how to test a class

Hi *, the class I need to test is:

https://gist.github.com/49ef28014bb648ffa63e

I know my question is very generic, but I honestly fail to see how to test
something that is so strictly procedural and so dependent to the
platform/libraries.
Should I mock/stub filesystem, services and pretty much everything that is in
there and test how it responds to different inputs, or adopt an
"integration style" ?
How would you proceed in this case ? (you can refer to RSpec book and point to
parts that are relevant).

  ngw

-- 
[ 926381, 23200231779, 1299022, 1045307475 ].collect { |a| a.to_s( 36 ) }.join(
" " )
Nicholas Wieland (ngw)
ngw at nofeed.org
http://www.nofeed.org

On 13 Apr 2011, at 02:48, Nicholas Wieland wrote:
> Hi *, the class I need to test is:
> 
> https://gist.github.com/49ef28014bb648ffa63e
> 
> I know my question is very generic, but I honestly fail to see how to test
something that is so strictly procedural and so dependent to the
platform/libraries.
> Should I mock/stub filesystem, services and pretty much everything that is
in there and test how it responds to different inputs, or adopt an
"integration style" ?
> How would you proceed in this case ? (you can refer to RSpec book and point
to parts that are relevant).
> 
>  ngw
It depends on what you''re worried about breaking. It looks to me like
the unpack method is the most likely one to go wrong, and the most likely one to
grow with more cases, so I''d focus my effort on that.

You have about three distinct responsibilities going on in this class -
there''s something which sets up a directory structure, something which
fetches zip files from S3, and something which unpacks a zip file into a folder
structure. If you encapsulated what''s going on in #sandbox into a
Target or Destination or Sandbox class, with methods like write_stylesheet and
and write_image, you could mock out that object easily. Similarly if you create
a wrapper object around the responsibility of calling S3, you''d be able
to test your unpack method with some fixture zip files from your test suite. The
Sandbox and S3Fetcher classes will be pretty simple and unlikely to break, so
you might not need to test them at all, other than with a quick manual
integration test.

Depending on how mission critical this code is, you might want a simple
integration test to check it all wires up, but that depends on you appetite for
risk, how often this code will change, and where that change happens. If all you
do is add more cases to the unpack method, you''re going to be safe
testing those changes with specs and running a quick manual test.
> 
> -- 
> [ 926381, 23200231779, 1299022, 1045307475 ].collect { |a| a.to_s( 36 )
}.join( " " )
> Nicholas Wieland (ngw)
> ngw at nofeed.org
> http://www.nofeed.org
> 
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users
cheers,
Matt

--
Freelance programmer & coach
Founder, http://relishapp.com
+44(0)7974430184 | http://twitter.com/mattwynne

Hi Nicholas,

You have little choice but to mock external dependencies like S3 and
the file system in order to be able to do TDD. The problem is that, as
Matt said, if it''s a mission critical feature you''ll want to
create
infrastructure to run tests against a real environment (even if it''s
just a smoke suite that''s separate from the unit tests).

Take a look at
https://github.com/thoughtworks/cruisecontrol.rb/blob/master/test/file_sandbox.rb
which deals with this kind of issue in CC.rb for a (what I consider) a
rather nice way of dealing with this.

Best,
Sidu.
http://c42.in
http://about.me/ponnappa


On 13 April 2011 07:18, Nicholas Wieland <ngw at nofeed.org>
wrote:
> Hi *, the class I need to test is:
>
> https://gist.github.com/49ef28014bb648ffa63e
>
> I know my question is very generic, but I honestly fail to see how to test
something that is so strictly procedural and so dependent to the
platform/libraries.
> Should I mock/stub filesystem, services and pretty much everything that is
in there and test how it responds to different inputs, or adopt an
"integration style" ?
> How would you proceed in this case ? (you can refer to RSpec book and point
to parts that are relevant).
>
> ?ngw
>
> --
> [ 926381, 23200231779, 1299022, 1045307475 ].collect { |a| a.to_s( 36 )
}.join( " " )
> Nicholas Wieland (ngw)
> ngw at nofeed.org
> http://www.nofeed.org
>
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users
>