Ruby factory bot

Library for creating test data in ruby.

NOTE:

There is also ruby factory_bot_rails.

Documentation

official docs (book)	https://thoughtbot.github.io/factory_bot/
official docs	https://github.com/thoughtbot/factory_bot/wiki
quickstart docs	https://github.com/thoughtbot/factory_bot/blob/master/GETTING_STARTED.md
github	https://github.com/thoughtbot/factory_bot

Tutorials

factorybot without orm

https://thoughtbot.com/blog/tips-for-using-factory-girl-without-an-orm

Basics

FactoryBot.define do
  factory :user do                        # <-- User class
    first_name { "John" }                 # <-- value between brackets
    last_name  { "Doe" }
    stats = { {"a" => nil, "b" => nil} }  # <-- double quotes for hash
    admin { false }
  end
end

user = build(:user)             # instantiates User
user = create(:user)            # instantiates User, calls #save() method
users = create_list(:user, 10)  # create 10x users
stub = build_stubbed(:user)     # creates stub (all attributes/methods, and associations are faked)

attrs = attributes_for(:user)  # creates hash to instantiate User instance

# can be used in 'do' block
create(:user) do |user|
  user.posts.create(attributes_for(:post))
end

Associations

factory :post do
  association :author                  # assigned factory :author
  association :author, factory: :user  # assigned to `author`, but uses facotry `:user`
end

Traits

Traits are implemented as constructor arguments.
They are presets of object-attribute values.

FactoryBot.define do
  factory :user do
    first_name = "Alex"
    last_name = "Guthrie"
    languages = ["English"]

    trait :bilingual do
      languages = ["English", "French"]
    end
  end
end

FactoryBot.create(:user, :bilingual)  # <- creates a bilingual user

Stubbing Methods

FactoryBot is designed not to alter your object. This is ugly, but effective.

FactoryBot.define do
  factory :user do
    after(:build) do |user, _evaluator|
      user.define_singleton_method(:fetch_age) { 30 }
    end
  end
end