On Dec 7, 2011, at 4:07 AM, Pat Maddox wrote: > On Dec 7, 2011, at 1:57 AM, Nikolay Sturm wrote: > >> * David Chelimsky [2011-12-07]: >>>> reading "Growing Object-Oriented Software, guided by tests", I came >>>> across the distinction of class, role and responsibility. >>>> >>>> While classes are classes and responsibilities could be mapped to public >>>> methods, I wonder how to specify roles in my specs. Does anyone have >>>> experiences with this? >>>> >>>> cheers, >>>> >>>> Nikolay >>> >>> https://www.relishapp.com/rspec/rspec-core/docs/example-groups/shared-examples >> >> Sorry, but I don't see how that helps. In my understanding, roles are a >> set of related responsibilities. If responsibilities map roughly to >> public methods, than a role should be a subset of a class' API. I don't >> see where I should want to share example groups. > > You can use shared example groups to test a subset of a class's API.
Nikolay - just because they're shareable doesn't mean they have to be shared :) As Pat suggests, you can use them to specify a subset of a single object's API. That said, one goal of thinking of roles is code that is easy to extend thanks to polymorphism. You might have onlly one class that satisfies a role now, but you might add another later. Shared examples allow you to just drop in a spec for that part of the new object's responsibilities. I blogged about this a while back: http://blog.davidchelimsky.net/2010/11/07/specifying-mixins-with-shared-example-groups-in-rspec-2/ - the focus of that entry is on Modules, but you could just as easily think in terms of roles (since a Module often represents a role). The stuff about spec'ing the what happens when you include the module doesn't really apply, but the stuff about spec'ing similar behavior across different objects does. HTH, David _______________________________________________ rspec-users mailing list rspec-users@rubyforge.org http://rubyforge.org/mailman/listinfo/rspec-users
