Tightening controller test

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Problem

One day i saw a snippet of code inside controller test, which is green and sadly is a little hard to understand:

describe BooksController, type: :controller do
  describe "GET #index" do
    before do
      expect(Book).to receive_message_chain(:published, :latest, :limit).with(10)
      create_list :book, 5, :published
      create_list :book, 3
    end
 
    it { get :index }
  end
end

After a while, i realized this tests are trying to assert query invoked in an index action. Unfortunately at first sight it doesn’t have a clear intent about what we are going to test.

Besides that this test is not integrated with the views that will be rendered. The test still pass against this code below, if we forgot to supply view variable:

def index
  books = Book.published.latest.limit(10) # view need @books
end

Ok, we have a weak controller test.

Solution

I think there are two solutions, first is refactor the controller test to be more clear intent and tight, second is tell a controller example to render views.

We can apply arrange-act-assert (AAA) pattern for this test and add more assertion. AAA is simple concept: setup context -> execute thing -> verify expected behavior.
Tell controller example to render view using render_views method and add more assertion with view.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
describe BooksController, type: :controller do describe "GET #index", :focus do render_views 
    # arrange let!(:published_book){ create :book, :published } let!(:unpublished_book){ create :book } 
    # act before do get :index end 
    # assertion it "response ok & render correct view" do expect(response).to have_http_status :ok expect(response).to render_template :index end 
    it "query latest published books" do expect(assigns(:books)).to include published_book end 
    it "contain only published book title" do expect(response.body).to include published_book.title expect(response.body).not_to include unpublished_book.title end end class="k">end

Tightening controller test

Problem

Solution

Written by

Agung Prasetyo

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devblog of @sgt_mactavish