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!
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