Simple One-Liner Tests for Rails

Without Shoulda Matchers

describe User do
  it 'is not valid if its username is the same as another user within the same account' do
    _existing_user = FactoryBot.create(:user,
      username: 'johnsmith',
      account_id: 1
    )
    user = FactoryBot.build(:user,
      username: 'johnsmith',
      account_id: 1
    )
    expect(user).not_to be_valid
  end

  it 'is valid if its username is the same as another user within the same account, but for different case' do
    _existing_user = FactoryBot.create(:user,
      username: 'johnsmith',
      account_id: 1
    )
    user = FactoryBot.build(:user,
      username: 'JohnSmith',
      account_id: 1
    )
    expect(user).to be_valid
  end
end

With Shoulda Matchers

describe User do
  context 'validations' do
    before { FactoryBot.build(:user) }

    it do
      should validate_uniqueness_of(:username).
        scoped_to(:account_id).
        case_insensitive
    end
  end
end

Extensive matchers for ActiveModel, ActiveRecord, and ActionController

ActiveModel validation matchers Other ActiveModel matchers ActiveRecord validation matchers ActiveRecord association matchers ActionController matchers Independent matchers

ActiveModel validation matchers

Example: validate_presence_of matcher

Post model

class Robot
  include ActiveModel::Model
  attr_accessor :arms

  validate :arms, presence: true
end

Test using RSpec

describe Robot do
  it { should validate_presence_of(:arms) }
end

Test using Shoulda Context

class RobotTest < ActiveSupport::TestCase
  should validate_presence_of(:arms)
end

Other ActiveModel matchers

Example: have_secure_password matcher

Post model

class User
  include ActiveModel::Model
  include ActiveModel::SecurePassword
  attr_accessor :password

  has_secure_password
end

Test using RSpec

describe User do
  it { should have_secure_password }
end

Test using Shoulda Context

class UserTest < ActiveSupport::TestCase
  should have_secure_password
end

ActiveRecord validation matchers

Example: validate_uniqueness_of matcher

Post model

class Post < ActiveRecord::Base
  validates_uniqueness_of :slug,
    scope: :user_id,
    message: 'duplicate slug within same user_id',
    case_insensitive: true
end

Test using RSpec

describe Post do
  context 'validations' do
    subject { FactoryBot.build(:post) }

    it do
      should validate_uniqueness_of(:slug).
        scoped_to(:user_id).
        with_message('duplicate slug within same user_id').
        case_insensitive
    end
  end
end

Test using Shoulda Context

class PostTest < ActiveSupport::TestCase
  context 'validations' do
    subject { FactoryBot.build(:post) }

    should validate_uniqueness_of(:slug).
      scoped_to(:user_id).
      with_message('duplicate slug within same user_id').
      case_insensitive
  end
end

ActiveRecord association matchers

Example: have_many matcher

Post model

class Person < ActiveRecord::Base
  has_many :acquaintances,
    through: :friends,
    class_name: 'Person'
end

Test using RSpec

describe Person do
  it do
    should have_many(:acquaintances).
      through(:friends).
      class_name('Person')
  end
end

Test using Shoulda Context

require 'test_helper'

class PersonTest < ActiveSupport::TestCase
  should have_many(:acquaintances).
    through(:friends).
    class_name('Person')
end

ActionController matchers

Example: rescue_from matcher

Routes

class ApplicationController < ActionController::Base
  rescue_from ActiveRecord::RecordNotFound, with: :render_not_found

  private

  def render_not_found
    # ...
  end
end

Test using RSpec

describe ApplicationController do
  it do
    should rescue_from(ActiveRecord::RecordNotFound).
      with(:render_not_found)
  end
end

Test using Shoulda Context

class ApplicationControllerTest < ActionController::TestCase
  should rescue_from(ActiveRecord::RecordNotFound).
    with(:render_not_found)
end

Independent matchers

Example: delegate_method matcher

app/models/courier.rb

require 'forwardable'

class Courier
  extend Forwardable

  attr_reader :post_office

  def_delegators :post_office, :deliver

  def initialize
    @post_office = PostOffice.new
  end
end

Test using RSpec

describe Courier do
  it { should delegate_method(:deliver).to(:post_office) }
end

Test using Shoulda Context

class CourierTest < Minitest::Test
  should delegate_method(:deliver).to(:post_office)
end

Simple One-Liner Tests for Rails

Without Shoulda Matchers

With Shoulda Matchers

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More Readable Results

Extensive matchers for ActiveModel, ActiveRecord, and ActionController

List of Matchers

ActiveModel

ActiveRecord

ActionController

Independent Matchers