rspec users - Feb 2012 - Game development: how to test interactions like an attack?

Hello,

I''m writing webgames with Rails and I want to test my code (and even
TDD) but I''m really stuck figuring what to test.
I read a lot of articles on the subject but I still don''t know what to
do in my case: how to start?

For instance, a simple interaction in most game: a character attacks another
one. What should be tested?
With words, here is what I can say about an attack:

It''s an action from an attacker to a target.
The attacker may have a weapon and the target may have an armor.
In order to be successful, the attacker must hit the target, according to the
combat skill of each actor and the precision of the weapon.
When the target is hit, it receives damages according to the attacker power, the
weapon damages and the resistance.
A part of these damages may be absorbed by it''s armor.
So, what could my specs be with that? I really can''t start? :(

Thanks for your help!

Hello,

I''m writing webgames with Rails and I want to test my code (and even
TDD) but I''m really stuck figuring what to test.
I read a lot of articles on the subject but I still don''t know what to
do in my case: how to start?

For instance, a simple interaction in most game: a character attacks another
one. What should be tested?
With words, here is what I can say about an attack:

It''s an action from an attacker to a target.
The attacker may have a weapon and the target may have an armor.
In order to be successful, the attacker must hit the target, according to the
combat skill of each actor and the precision of the weapon.
When the target is hit, it receives damages according to the attacker power, the
weapon damages and the resistance.
A part of these damages may be absorbed by it''s armor.
So, what could my specs be with that? I really can''t start? :(

Thanks for your help!

On 2 Feb 2012, at 09:50, Romain Tribes wrote:
> Hello,
> 
> I''m writing webgames with Rails and I want to test my code (and
even TDD) but I''m really stuck figuring what to test.
> I read a lot of articles on the subject but I still don''t know
what to do in my case: how to start?
> 
> For instance, a simple interaction in most game: a character attacks
another one. What should be tested?
> With words, here is what I can say about an attack:
> 
> It''s an action from an attacker to a target.
> The attacker may have a weapon and the target may have an armor.
> In order to be successful, the attacker must hit the target, according to
the combat skill of each actor and the precision of the weapon.
> When the target is hit, it receives damages according to the attacker
power, the weapon damages and the resistance.
> A part of these damages may be absorbed by it''s armor.
> So, what could my specs be with that? I really can''t start? :(
Have you started to design a domain model for this? Could we see a picture?

cheers,
Matt

--
Freelance programmer & coach
Author, http://pragprog.com/book/hwcuc/the-cucumber-book
Founder, http://www.relishapp.com/
Twitter, https://twitter.com/mattwynne


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I always find it''s very good to start simply.

Make the simplest spec you can imagine, then the next, and so on...

What is a spec? Some of this stuff might seem so obvious... for example... when
you start playing your game, you expect that it''ll present you with
something... write a test for that. Basically any time you''re doing
something yourself to run your code, you should be able to spec it. That way you
don''t have to manually test things out.

So I''ve got a basic question: have you started building your game? Do
you have any idea of the requirements at all?

Julian


On 02/02/2012, at 8:20 PM, Romain Tribes wrote:
> Hello,
> 
> I''m writing webgames with Rails and I want to test my code (and
even TDD) but I''m really stuck figuring what to test.
> I read a lot of articles on the subject but I still don''t know
what to do in my case: how to start?
> 
> For instance, a simple interaction in most game: a character attacks
another one. What should be tested?
> With words, here is what I can say about an attack:
> 
> It''s an action from an attacker to a target.
> The attacker may have a weapon and the target may have an armor.
> In order to be successful, the attacker must hit the target, according to
the combat skill of each actor and the precision of the weapon.
> When the target is hit, it receives damages according to the attacker
power, the weapon damages and the resistance.
> A part of these damages may be absorbed by it''s armor.
> So, what could my specs be with that? I really can''t start? :(
> 
> Thanks for your help!
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users

On Feb 2, 2012, at 2:20 AM, Romain Tribes wrote:
> Hello,
> 
> I''m writing webgames with Rails and I want to test my code (and
even TDD) but I''m really stuck figuring what to test.
> I read a lot of articles on the subject but I still don''t know
what to do in my case: how to start?
> 
> For instance, a simple interaction in most game: a character attacks
another one. What should be tested?
> With words, here is what I can say about an attack:
> 
> It''s an action from an attacker to a target.
> The attacker may have a weapon and the target may have an armor.
> In order to be successful, the attacker must hit the target, according to
the combat skill of each actor and the precision of the weapon.
> When the target is hit, it receives damages according to the attacker
power, the weapon damages and the resistance.
> A part of these damages may be absorbed by it''s armor.
What you just listed ^^ is the behavior of the system. The great thing about BDD
is you can start _without_ needing to know the implementation details.

The first step you can take is to setup some high level, outside-in testing.
These tests interact with your program the same way as a user would.
You''ll hear these tests called many different names: acceptance,
integration, functional, application, system, etc. I don''t believe
there is a correct term anymore, as everyone interprets the definitions
differently.

In the case of Ruby, you have excellent tools available for these tests: RSpec,
MiniTest, Cucumber (used with RSpec or MiniTest). Personally, I prefer to use
only RSpec, so let''s use that as an example.

Pick a simple behavior to start off with. A good one is something that the user
_has_ to do first. For example, in a Rails app, this would be signing up:

# project/spec/functional/signing_up_spec.rb

describe ''Signing up'' do
  context ''by visiting the sign up page'' do
    before { go_to_the_sign_up_page }

    context ''and submitting the sign up form with valid data''
do
      before { submit_the_sign_up_form_with_valid_data }

      it ''redirects to the dashboard page'' do
        expect_to_be_on_the_dashboard_page
      end
    end
  end
end

Great, now I have my first spec. Obviously, if you tried to run this, it would
completely fail since you haven''t written any implementation code.

At this point, writing more high level tests doesn''t make sense because
we haven''t got the first one to pass. Let''s focus on doing
that.

Alright, so as we can see from our spec, the first thing it does is "visits
the sign up page". Okay, we need a sign up page. The sign up page is a
single entity, and we''re no longer concerned with how it interacts with
other parts of the system. Therefore, we need to drop down to the
"unit" level, and subsequently create a unit test for this entity:

# project/spec/unit/sign_up_page_spec.rb

describe SignUpPage do
  context ''given a coupon code'' do
    it ''sets a hidden field called "coupon_code" with its
value as the code'' do
      expect_a_hidden_field_with_a_particular_value
    end
  end
end

Notice how we are still focusing on behavior. The difference is, we are only
concerned with the behavior of just this entity/unit, not on its role or
interactions in the system. Because of this, you''ll sometimes see
people call them "isolated unit tests".

After you get the unit test to pass, you can check to see if the high level test
can pass. The BDD process involves jumping back and forth between unit and high
level tests. However, the high level tests are _always_ your guide. You drive
the high level tests, and in turn they drive the unit tests.

I think this is enough to get you started, but looking at your post, this could
be your first high level test:

describe ''Attacking'' do
  let!(:attacker) { create_attacker }
  let!(:target) { create_target }

  context ''on the playing page'' do
    before { go_to_the_playing_page }

    describe ''when an attacker hits a target'' do
      before { hit_target(attacker, target) }

      it ''displays the damages on the target'' do
        expect_page_to_display_the_correct_damage_amount
      end
    end
  end
end

> When the target is hit, it receives damages according to the attacker
power, the weapon damages and the resistance.
> So, what could my specs be with that? I really can''t start? :(
> 
> Thanks for your help!
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users

Romain,

On 2/2/12 4:50 AM, Romain Tribes wrote:
> Hello,
>
> I''m writing webgames with Rails and I want to test my code (and
even TDD) but I''m really stuck figuring what to test.
> I read a lot of articles on the subject but I still don''t know
what to do in my case: how to start?
>
> For instance, a simple interaction in most game: a character attacks
another one. What should be tested?
> With words, here is what I can say about an attack:
>
> It''s an action from an attacker to a target.
> The attacker may have a weapon and the target may have an armor.
> In order to be successful, the attacker must hit the target,
> according to the combat skill of each actor and the precision of the
> weapon.
> When the target is hit, it receives damages according to the attacker
> power, the weapon damages and the resistance.
> A part of these damages may be absorbed by it''s armor.
> So, what could my specs be with that? I really can''t start? :(
Start with the simplest scenario you can imagine.

What would happen if the attacker had no weapon and the target had no 
armor? I can imagine scenarios with each having little skill, with each 
having great skill, and the two unbalanced scenarios where one has great 
skill and the other little.

Is it possible for the attacker to miss?

  - George

-- 
  ----------------------------------------------------------------------
   * George Dinwiddie *                      http://blog.gdinwiddie.com
   Software Development                    http://www.idiacomputing.com
   Consultant and Coach                    http://www.agilemaryland.org
  ----------------------------------------------------------------------

Thanks for your attention and your answers!

I worked on that the whole afternoon: it''s really timeconsuming when
you
are not used to test!  
My code is on GitHub : https://github.com/Sephi-Chan/LearnToTest

As I said I read a lot of stuff about testing and TDD. Unfortunately, most 
of the time it''s for systems with very little business logic and I
don''t
believe I can learn good software design with simplistic systems 
(todo-lists/blogs/...).  
It''s why I want to build something more interesting and focus on the 
business logic: not the controllers/views stuff.

Anyway I hope you''ll keep helping me to review and give me precious 
advices. :)

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