From: Simon Strandgaard <neoneye@...>
Date: 2004-05-29T20:39:03+09:00
Subject: Re: Test::Unit: assert_follows_spec() (or something like that)

David Garamond wrote:
> David Garamond wrote:
> > For deterministic functions/methods, the same set of inputs should 
> > always produces the same output. What about adding something like:
> > 
> >  assert_follows_spec(method_or_class_name, spec)
> > 
> > Where spec is an array of input and output pairs (and optionally an 
> > exception, if the input should not be accepted):
> > 
> >  [{input => [1, 1, 1], output => 1},
> >   {input => [8, 1, 2], output => 4},
> >   {input => [8, 3, 4], output => 6},
> >   {input => [4, 3, 2], output => 6},
> >   {input => [1, 2, nil], exception => ArgumentError},
> >   {input => [1, 2, 0], exception => ZeroDivisionError}]
> 
> Of course the above should be written as :input, :output, etc. Too much 
> writing YAML, I guess :-).
> 
> Some more ideas:
> 
> * max_delta for floats:
> 
>   {:input => [1, 3.0], :output    => 0.333333333333333,
>                        :max_delta => 0.000000000000001}
> 
> * support for non-deterministic func/methods, like 'output_in' (multiple 
> possible outputs), 'output_class' and 'output_range' (for any acceptable 
> output or a certain clas and inside a certain range). e.g. for testing 
> Kernel#rand:
> 
>   [{:input => [1], :output => 0},
>    {:input => [3], :output_in => [0, 1, 2]},
>    {:input => [],  :output_class => Float,
>                    :output_range => 0...1.0}]
> 

What about :in  :out  :fail  :error


> Basically, I'm seeing assert_follows_spec (or assert_calls, or whatever) 
> as simply an aggregate of lots of simpler asserts (assert_equals, 
> assert_raises, etc) as one big assert. The difference is, it's shorter 
> (it saves some keystrokes), nicer/tidier, and the "spec" itself is a 
> data structure and can be changed/manipulated/displayed/etc more easily.
> 
> Of course, this "spec" in many cases cannot cover all aspects of the 
> testing, only simpler ones. So perhaps a better name for "spec" is desired.

What about 'assert_array' as name.. it sort of indicates that there
are multiple element to compare against.

def func(val)
  val + val
end
expected = [
  { :in=>1, :out=>2 },
  { :in=>'a', :out=>'aa' },
]
assert_array(expected, :func)

Or perhaps

assert_inout(expected, :func)

-- 
Simon Strandgaard