Factory Bot Cheatsheet · Cheat Sheets

Factory Bot is a fixtures replacement with a straightforward definition syntax, support for multiple build strategies, and support for multiple factories for the same class.

Factories

Introduction

Factory Bot is a helper library for writing factories in Ruby test suites. It was previously known as Factory Girl. For legacy versions, use FactoryGirl instead of FactoryBot.

Factory Bot Documentation (thoughtbot.github.io)
Getting Started Guide (github.com)
Source Code (github.com)

Defining Factories

FactoryBot.define do
  factory :user do
    first_name { 'John' }
    last_name  { 'Doe' }
    birthdate  { 21.years.ago }
    admin      { false }

    sequence(:username) { |n| "user#{n}" }
  end
end

See: Defining Factories.

Additional Options

Custom Class Name

factory :user, class: 'User' do
  ···
end

Aliases

factory :user, aliases: [:author] do
  ···
end

Usage Strategies

Building an Instance

FactoryBot.build(:user)

Other Build Strategies

build(:user)           # → model instance (not saved)
create(:user)          # → model instance (saved to database)
attributes_for(:user)  # → hash of attributes
build_stubbed(:user)   # stubbed out attributes (no DB hits)

Overriding Attributes

build(:user, name: 'John')

Building Collections

create_list(:user, 3)
build_list(:user, 3)

Associations

Defining Associations

factory :post do
  association :author, factory: :user
  association :author, factory: [:user, :admin]
end

Implicit Association

factory :post do
  author  # assumes there is a factory named :author
end

After-Create Hooks

factory :post do
  after :create do |post|
    create :theme, post: post             # has_one
    create_list :comment, 3, post: post   # has_many
  end
end

Advanced Features

Traits

factory :user do
  trait :admin do
    admin { true }
  end
end

create :user, :admin

Traits allow you to group related attributes and behaviors together. See: Traits.

Nested Factories

factory :user do
  first_name { 'John' }

  factory :sample_user do
    first_name { FFaker::Name.first_name }
  end
end

create :sample_user

See: Inheritance.

Sub-factories

factory :user do
  ···
end

factory :sample_user, parent: :user do
  first_name { FFaker::Name.first_name }
end

create :sample_user

Sub-factories work similarly to nested factories using the parent option.

Transient Attributes

factory :user do
  transient do
    upcased { true }
  end

  after :create do |user, options|
    user.name.upcase! if options.upcased
  end
end

create(:user, upcased: true)

Transient attributes are not assigned directly to model fields, but are accessible inside callbacks and hooks. See: Transient Attributes.

Standard File Locations

test/factories.rb
spec/factories.rb
test/factories/*.rb
spec/factories/*.rb

Place your factory definition files in any of these paths for automatic loading.

References

Factory Bot Getting Started Guide