Testing polymorphic associations with RSpec
polymorphic-associations, rspec, ruby-on-rails
Solution
I feel the latter is testing better than the former, but have no confidence.
If you intended to implicitly ask which was "better", then that question is not a good fit for StackOverflow.
Or are they equivalent to each other?
In the sense that the setup results in the same `Link` object being created, I would say that yes, they are equivalent. However, the second tests the association helper method set up for `Book`, which you may find desirable.
Problem
I'm writing RSpec code for polymorphic associations. I have two testing ideas that - Use Factory Girl to build polymorphic associations - Use rails methods to build polymorphic associations. Here are the pieces of the code I wrote (relevant codes are at the bottom): 1) link_spec.rb, creating the association with FactoryGirl. ``` describe "Book links" do let(:book) { FactoryGirl.create(:book) } let(:book_link) { FactoryGirl.create(:book_link, linkable: book) } subject{ book_link } it { should be_valid } it { should respond_to(:url) } it { should respond_to(:linkable) } its(:linkable) { should eq book } end ``` 2) link_spec.rb, creating the association through rails methods. ``` describe "Book links" do let(:book) { FactoryGirl.create(:book) } let(:link) { book.links.create(url: "http://example.com") } subject { link } it { should be_valid } it { should respond_to(:url) } it { should respond_to(:linkable) } its(:linkable) { should eq book } end ``` I feel the latter is testing better than the former, but have no confidence. Or are they equivalent to each other? book.rb ``` class Book < ActiveRecord::Base has_many :links, as: :linkable end ``` link.rb ``` class Link < ActiveRecord::Base belongs_to :linkable, polymorphic: true end ``` factories.rb ``` factory :book do title "Foo bar" author "John" end factory :book_link, class: "Link" do association :linkable, factory: :book url "http://examle.com" end ```