index.html.md

position	chapter
7	Factory

rom-factory

rom-factory provides a simple API for creating and persisting ROM::Struct's. If you already know FactoryBot you'll definitely understand the concept.

Installation

First of all you need to define a ROM Container for Factory. For example if you are using rspec, you can add these lines to spec_helper.rb. Also you need to require here all files with Factories.

Factory = ROM::Factory.configure do |config|
  config.rom = my_rom_container
end

Dir[File.dirname(__FILE__) + '/support/factories/*.rb'].each { |file| require file }

Usage

Define factory

# 'spec/support/factories/users.rb'

Factory.define(:user) do |f|
  f.name 'John'
  f.age 42
end

Specify relations

You can specify ROM relation if you want. It'll be pluralized factory name by default.

Factory.define(:user, relation: :people) do |f|
  f.name 'John'
  f.age 42
end

Specify namespace for your structs

Struct User will be found in MyApp::Entities namespace

Factory.define(:user, struct_namespace: MyApp::Entities) do |f|
  # ...
end

Sequences

You can use sequences for uniq fields

Factory.define(:user) do |f|
  f.name 'John'
  f.sequence(:email) { |n| "john#{n}@example.com" }
end

Timestamps

Factory.define(:user) do |f|
  f.name 'John'
  f.timestamps
  # same as
  # f.created_at { Time.now }
  # f.updated_at { Time.now }
end

Associations

• belongs_to

Factory.define(:group) do |f|
  f.name 'Admins'
end

Factory.define(:user) do |f|
  f.name 'John'
  f.association(:group)
end

• has_many

Factory.define(:group) do |f|
  f.name 'Admins'
  f.association(:user, count: 2)
end

Factory.define(:user) do |f|
  f.name 'John'
end

Extend already existing factory

Factory.define(:user) do |f|
  f.name 'John'
  f.admin false
end

Factory.define(admin: :user) do |f|
  f.admin true
end

# Factory.structs[:admin]

Traits

Factory.define(:user) do |f|
  f.name 'John'
  f.admin false

  f.trait :with_age do |t|
    t.age 42
  end
end

# Factory.structs[:user, :with_age]

Build-in Faker objects

Factory.define(:user) do |f|
  f.email { fake(:internet, :email) }
end

Unique values with fake

Passing the unique: true option will use Faker's unique feature

Factory.define(:user) do |f|
  f.email { fake(:internet, :email, unique: true) }
end

Dependent attributes

Attributes can be based on the values of other attributes:

Factory.define(:user) do |f|
  f.full_name { fake(:name) }
  # Dependent attributes are inferred from the block parameter names:
  f.login { |full_name| full_name.downcase.gsub(/\s+/, '_') }
  # Works with sequences too:
  f.sequence(:email) { |n, login| "#{login}-#{n}@example.com" }
end

Build and persist objects

# Create in-memory object
Factory.build(:user)

# Persist struct in database
Factory.create(:user)

# Override attributes
Factory.create(:user, age: 24)

# Build and Create via #[] accessors
Factory.structs[:user]
Factory[:user]