CODEWITHSUNDEEP
ruby-on-railsrspec
Mich Dart
Mich Dart

Reputation: 2422

RSpec, how to test initialize inside a module

I have this module:

module TicketsPresenters

    class ShowPresenter
      def initialize(ticket_or_id = nil)
        unless ticket_or_id.nil?
          if ticket_or_id.is_a?(Ticket)
            @ticket = ticket_or_id
          else
            @ticket = Ticket.find(ticket_or_id)
          end
      end
    end

end

I'd like to test if the initialize() method sets up the object properly, when I pass an integer or directly the object instance.

Upvotes: 1

Views: 2461

Answers (1)

Peter Brown
Peter Brown

Reputation: 51697

There's probably a dozen ways to answer this, but I'll give you the RSpec format that I prefer.

The following assumes you have a reader method for ticket (ie attr_reader :ticket) in your ShowPresenter class. It also assumes you are creating your Ticket object with valid parameters so it gets saved.

describe TicketsPresenters::ShowPresenter do
  context '#initialize' do
    let!(:ticket) { Ticket.create!(...) }

    context 'with an id' do
      subject { TicketsPresenters::ShowPresenter.new(ticket.id) }
      its(:ticket) { should == ticket }
    end

    context 'with a Ticket object' do
      subject { TicketsPresenters::ShowPresenter.new(ticket) }
      its(:ticket) { should == ticket }
    end

    context 'with nothing' do
      subject { TicketsPresenters::ShowPresenter.new }
      its(:ticket) { should be_nil }
    end
  end
end

Note: I'm a fan of FactoryGirl so I would personally prefer to use Factory.create(:ticket) over Ticket.create!(...) since it allows you define a valid Ticket object in one place and you don't need to update it in all your tests if that definition changes.

Another testing position that people take is to not use database persistance at all. This is probably not a concept I would suggest to people new to Ruby or RSpec since it is a little harder to explain and would require more OOP knowledge. The upside is that it removes the database dependency and tests are faster and more isolated.

describe TicketsPresenters::ShowPresenter do
  context '#initialize' do
    let(:ticket) { mock(:ticket, id: 1) }

    before do
      ticket.stub(:is_a?).with(Ticket) { true }
      Ticket.stub(:find).with(ticket.id) { ticket }
    end

    context 'with an id' do
      subject { TicketsPresenters::ShowPresenter.new(ticket.id) }
      its(:ticket) { should == ticket }
    end

    context 'with a Ticket object' do
      subject { TicketsPresenters::ShowPresenter.new(ticket) }
      its(:ticket) { should == ticket }
    end

    context 'with nothing' do
      subject { TicketsPresenters::ShowPresenter.new }
      its(:ticket) { should be_nil }
    end
  end
end

Upvotes: 2

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