Rails & RSpec - Testing Concerns class methods - ruby-on-rails

Question

I have the following (simplified) Rails Concern:
module HasTerms
extend ActiveSupport::Concern
module ClassMethods
def optional_agreement
# Attributes
#----------------------------------------------------------------------------
attr_accessible :agrees_to_terms
end
def required_agreement
# Attributes
#----------------------------------------------------------------------------
attr_accessible :agrees_to_terms
# Validations
#----------------------------------------------------------------------------
validates :agrees_to_terms, :acceptance => true, :allow_nil => :false, :on => :create
end
end
end
I can't figure out a good way to test this module in RSpec however - if I just create a dummy class, I get active record errors when I try to check that the validations are working. Has anyone else faced this problem?

Answer 1

Check out RSpec shared examples.
This way you can write the following:
# spec/support/has_terms_tests.rb
shared_examples "has terms" do
# Your tests here
end
# spec/wherever/has_terms_spec.rb
module TestTemps
class HasTermsDouble
include ActiveModel::Validations
include HasTerms
end
end
describe HasTerms do
context "when included in a class" do
subject(:with_terms) { TestTemps::HasTermsDouble.new }
it_behaves_like "has terms"
end
end
# spec/model/contract_spec.rb
describe Contract do
it_behaves_like "has terms"
end

Answer 2

You could just test the module implicitly by leaving your tests in the classes that include this module. Alternatively, you can include other requisite modules in your dummy class. For instance, the validates methods in AR models are provided by ActiveModel::Validations. So, for your tests:
class DummyClass
include ActiveModel::Validations
include HasTerms
end
There may be other modules you need to bring in based on dependencies you implicitly rely on in your HasTerms module.

Answer 3

I was struggling with this myself and conjured up the following solution, which is much like rossta's idea but uses an anonymous class instead:
it 'validates terms' do
dummy_class = Class.new do
include ActiveModel::Validations
include HasTerms
attr_accessor :agrees_to_terms
def self.model_name
ActiveModel::Name.new(self, nil, "dummy")
end
end
dummy = dummy_class.new
dummy.should_not be_valid
end

Answer 4

Here is another example (using Factorygirl's "create" method" and shared_examples_for)
concern spec
#spec/support/concerns/commentable_spec
require 'spec_helper'
shared_examples_for 'commentable' do
let (:model) { create ( described_class.to_s.underscore ) }
let (:user) { create (:user) }
it 'has comments' do
expect { model.comments }.to_not raise_error
end
it 'comment method returns Comment object as association' do
model.comment(user, "description")
expect(model.comments.length).to eq(1)
end
it 'user can make multiple comments' do
model.comment(user, "description")
model.comment(user, "description")
expect(model.comments.length).to eq(2)
end
end
commentable concern
module Commentable
extend ActiveSupport::Concern
included do
has_many :comments, as: :commentable
end
def comment(user, description)
Comment.create(commentable_id: self.id,
commentable_type: self.class.name,
user_id: user.id,
description: description
)
end
end
and restraunt_spec may look something like this (I'm not Rspec guru so don't think that my way of writing specs is good - the most important thing is at the beginning):
require 'rails_helper'
RSpec.describe Restraunt, type: :model do
it_behaves_like 'commentable'
describe 'with valid data' do
let (:restraunt) { create(:restraunt) }
it 'has valid factory' do
expect(restraunt).to be_valid
end
it 'has many comments' do
expect { restraunt.comments }.to_not raise_error
end
end
describe 'with invalid data' do
it 'is invalid without a name' do
restraunt = build(:restraunt, name: nil)
restraunt.save
expect(restraunt.errors[:name].length).to eq(1)
end
it 'is invalid without description' do
restraunt = build(:restraunt, description: nil)
restraunt.save
expect(restraunt.errors[:description].length).to eq(1)
end
it 'is invalid without location' do
restraunt = build(:restraunt, location: nil)
restraunt.save
expect(restraunt.errors[:location].length).to eq(1)
end
it 'does not allow duplicated name' do
restraunt = create(:restraunt, name: 'test_name')
restraunt2 = build(:restraunt, name: 'test_name')
restraunt2.save
expect(restraunt2.errors[:name].length).to eq(1)
end
end
end

Answer 5

Building on Aaron K's excellent answer here, there are some nice tricks you can use with described_class that RSpec provides to make your methods ubiquitous and make factories work for you. Here's a snippet of a shared example I recently made for an application:
shared_examples 'token authenticatable' do
describe '.find_by_authentication_token' do
context 'valid token' do
it 'finds correct user' do
class_symbol = described_class.name.underscore
item = create(class_symbol, :authentication_token)
create(class_symbol, :authentication_token)
item_found = described_class.find_by_authentication_token(
item.authentication_token
)
expect(item_found).to eq item
end
end
context 'nil token' do
it 'returns nil' do
class_symbol = described_class.name.underscore
create(class_symbol)
item_found = described_class.find_by_authentication_token(nil)
expect(item_found).to be_nil
end
end
end
end