[TIP] running away from RSpec

Alfredo Deza alfredodeza at gmail.com
Sat Feb 12 13:26:10 PST 2011

On Sat, Feb 12, 2011 at 2:58 PM, Gary Bernhardt <gary.bernhardt at gmail.com>wrote:

> On Sat, Feb 12, 2011 at 10:34 AM, Alfredo Deza <alfredodeza at gmail.com>
> wrote:
> > This more of an open question I guess, but why there isn't a project in
> > Python that grabs the best features from RSpec
> > and implements them?
> As you suggest, it's impossible. Mote and PySpec are just fancy ways
> to name your tests: weak implementations of one tiny corner of RSpec.
> Mote uses horrible settrace magic; PySpec adds a bunch of
> domain-irrelevant noise. Neither even supports arbitrary context
> strings. RSpec is more terse, more expressive, removes the noise, and
> is an entirely reasonable thing to build in Ruby.
> That last point is important: it's not just that RSpec is possible in
> Ruby; it's actually idiomatic. I think that people don't realize just
> how easy it is to build its syntax. RSpec lets you say things like:
>  describe Integer do
>    it "adds numbers" do
>      (1 + 1).should == 2
>    end
>  end
> Looks complicated and magical, right? Nope. Here's an implementation
> of describe and it:
>  def describe(name)
>    puts name
>    yield
>  end
>  def it(name)
>    puts "- #{name}"
>    yield
>  end
> This will output the spec output that's become so familiar:
>  Integer
>  - adds numbers
> I spent a couple days of my life trying to get Python to do this when
> writing Mote and failed completely.
> The `2.should == 2` syntax is also simple, but here you can get close
> in Python. Expecter Gadget [1] lets you say `expect(1 + 1) == 2`. I
> still prefer RSpec because the statement reads as "subject,
> relationship, expected value".
> There's much more terseness to be had than this, though; the above is
> just the most trivial example. You can say things like:
>  describe Dog do
>    it { should have(4).feet }
>    it { should be_thirsty }
>  end
> This is totally stock RSpec (and totally self-contained).
> `have(4).feet` asserts that `Dog.new.feet.size == 4`; `be_thirsty`
> asserts that `Dog.new.thirsty?` returns true.
> The most equivalent Python is:
>    class DogTest:
>        def setup(self):
>            self.dog = Dog()
>        def test_that_it_has_4_feet(self):
>            assert len(self.dog.feet) == 4
>        def test_that_it_is_thirsty(self):
>            assert self.dog.is_thirsty()
> (Inline the dog construction if you like; that just moves the problem
> around.)
> Some Python programmers will probably turn their noses up at that
> RSpec example because it's fancy (I know I would've). I think that's
> unreasonable. It's significantly more terse *and* more readable than
> the Python: a combination we don't often get.

It is *very* difficult to talk about things that exist in other languages
that are great
and that they do not exist in Python.

It is also not a case of "if you like it so much just use BLEH". I just
think we can
come up with different and better things and should be talking about that

> "More readable" does depend on learning RSpec, but that's easy because
> it's so intuitive. And I bet that you knew exactly what it meant upon
> reading it, even if its mapping onto the Dog class wasn't obvious.
> Getting back to the point: you just can't do this stuff in Python.
> I've spent a lot of time over the last couple years thinking about
> this and eventually I just gave up.

I think that is why it is important to talk about stuff that is not
necessarily tied to
UnitTesting and the way things are currently done.

> It's one of the reasons that
> almost all of my programming is now done in Ruby.

> [1] https://github.com/garybernhardt/expecter
> --
> Gary
> http://blog.extracheese.org
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