On Jan 8, 2008 11:25 AM, Matt Patterson <[EMAIL PROTECTED]> wrote: > On 8 Jan 2008, at 19:14, Daniel Tenner wrote: > > > > Might be a personal thing, but my approach is that I try to test the > > public behaviour of the object. Testing private methods is, imho, > > getting dangerously close to specifying how the object does its > > business, rather than what it does. > > > > If you're a proponent of many-skinny-methods then you wind up with a > lot of public methods which should never need to be called by another > object, so making them private can be a good thing for general users > of the object.
There are several problems with this thinking: 1. It separates refactoring from BDD. Having several private helper methods is a result of refactoring. Refactoring is not only a design tool, but a central part of BDD. 2. It couples your specs too tightly to the implementation. If you rename/delete/add a private method, you need to update the spec, even though the object's public behavior didn't change. 3. It eliminates the effectiveness of specs as documentation. Reading the specs is one of the first things I do when examining some code. If I see examples of how to use it, except not really, because they're private methods, I'm going to be seriously confused or seriously pissed off. 4. It leads to violations of the "one defect, one broken test" guideline. Some spec that exercises public behavior covers this private method, as does its individual spec, so if it breaks, then you have two broken specs. Whether that's important is a matter of personal preference. There is no 1:1 mapping of specification example to method. You don't specify a method. You specify a behavior. There are no rules dictating the specification's granularity, as long as it helps you design your code in the beginning, and localize defects as your code base persists. Specifying private methods is, in my opinion, slightly less pleasant than week-old trout in my pillow. It means one of two things. At a code level, your method's visibility could just be off. At a conceptual level, you may be missing the point of BDD entirely. Pat _______________________________________________ rspec-users mailing list rspec-users@rubyforge.org http://rubyforge.org/mailman/listinfo/rspec-users
