sort mini test in rails - ruby-on-rails

Question

I'm new to rails and i've done a simple sorting of dates in descending order. and now i need to write a test for it. my controller looks like this
def index
#article = Article.all.order('date DESC')
end
i tried writing a test but it doesn't work this is my code
def setup
#article1 = articles(:one)
end
test "array should be sorted desc" do
sorted_array = article1.sort.reverse
assert_equal article1, sorted_array, "Array sorted"
end

Answer 1

You should write a better description, by saying what each part of the code refers to, like:
# this is my controller_whatever.rb
def index
#article = Article.all.order('date DESC')
end
#this is my test/controllers/controller_whatever_test.rb
def setup
#article1 = articles(:one)
end
...
In your case you didn't create a "sorting", you created a controller action that queries records in descending order, so to test it you either need a controller test or an integration test (controller tests I believe are being dropped of use in favour of integration ones), which are more complex, since you need to visit the path in the test, then assert that somehow your results are as expected.
I think the best way to do this is to actually create a scope for your model, use that when querying in index and then test that scope.
This would be something like:
# app/models/article.rb
scope :default -> { order(date: :desc) }
Which then you could test it with:
#test/models/article_test.rb
def setup
#articles = Article.all
end
test "should be most recently published first" do
assert_equal articles(:last), #articles.first
assert_equal articles(:first), #articles.last
end
And you would need two fixtures with different dates at least, but I would advise you to have 4 or 5 with different dates and written in a different order in the articles.yml file (to make sure the test passes because it's correct and not simply because of randomness), and change your index action to simply:
def index
#article = Article.all # since now you have a default_scope
end
(if you have other places where you query Articles and you need them ordered in another way, instead of a default_scope, create a particular one and use that, both on controller and model test)

Answer 2

I would write a functional test in a test class according to the controller of your index action.
I assume your controller is named ArticlesController then the test class name is ArticlesControllerTest placed in test/controllers/articles_controller_test.rb.
In the test method you call/request the index action of your controller and you check for a successful answer first. Then you catch the articles, which your controller returns in the #article1 instance variable, with assigns(:article1).
Now you could check your articles are set and you can check the dates. Here I loop through all articles in an easy way and compare the date of the article before is greater or equal to the date of the current article, because of the descending order. For a simple test it should be acceptable, because you should not have a big amount of test records. May be there's a better way to check the order.
class ArticlesControllerTest < ActionController::TestCase
test "index should provide sorted articles" do
get :index
assert_response :success
articles = assigns(:article1)
assert_not_nil articles
date = nil
articles.each do |article|
if date
assert date >= article.date
end
date = article.date
end
end
end
Read about Functional Tests for Your Controllers in the Rails 4.2 Guides for more information.