From: Tim Bates <tim@...>
Date: 2004-05-18T09:17:13+09:00
Subject: Re: How to duck type? - the psychology of static typing in Ruby

Gavin Sinclair wrote:
>>10:  def test_date
>>11:    @obj = Foo.new
>>12:    @obj.date = MyClass.new.notadate
>>13:    assert(@obj.date.respond_to?(:year))
>>14:  end
> 
> 
> 
> Now I'm no unit testing guru (I try...) but that test to me seems so
> trivial as to be pointless.  Since the code it's testing does
> absolutely nothing other than assignment, you're not testing the
> *code*, you're testing one possible input value.

You're right, that's a really stupid example, and I was hoping nobody 
would spot it. :P I tried to think of a better example, and failed, 
since my original example (`attr_accessor :date`) is so trivial as to 
not need unit testing. (Although the unit testing gurus may disagree 
with me, I tend not to write tests for attributes unless I have written 
extra code in them - I just assume that attr_accessor does what it's 
supposed to.)

> I think it would be more convincing to talk about unit tests covering
> the correct overall operation of the class under scrutiny, rather than
> examining some lowly accessor.

That's right, and the problem arises because the whole article revolves 
around writing an accessor method - partly because it's simple, and 
partly because that was what I was trying to write when I started the 
discussion on #ruby-lang. :) If you can think of a better example, I'll 
happily rewrite it.

> # But your psychological needs could differ from mine :)

No, they don't. You're absolutely correct, that unit test is so trivial 
as to be pointless. I don't bother to test attr_accessor either.

> The rest of the article's good, though.

Thanks. :D

Tim.

-- 
Tim Bates
tim@bates.id.au