Factory Bot

https://thoughtbot.github.io/factory_bot/
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Factory Bot is a fixtures replacement with a straightforward definition syntax, supporting multiple...
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### Install factory_bot_rails for Rails Projects

Source: https://thoughtbot.github.io/factory_bot/setup/summary

Add the factory_bot_rails gem to your Gemfile for seamless integration with Rails applications. This is the recommended approach for Rails users.

```ruby
gem "factory_bot_rails"
```

--------------------------------

### Configure factory_bot with Test::Unit

Source: https://thoughtbot.github.io/factory_bot/setup/summary

Include FactoryBot::Syntax::Methods in your Test::Unit::TestCase classes to use factory_bot syntax in your unit tests. This provides a convenient way to generate test data.

```ruby
class Test::Unit::TestCase
  include FactoryBot::Syntax::Methods
end
```

--------------------------------

### Configure factory_bot with RSpec

Source: https://thoughtbot.github.io/factory_bot/setup/summary

Include FactoryBot::Syntax::Methods in your RSpec configuration to enable factory_bot syntax within your tests. This allows you to use shorthand methods for creating factories.

```ruby
RSpec.configure do |config|
  config.include FactoryBot::Syntax::Methods
end
```

--------------------------------

### Factory Bot Build Strategies

Source: https://thoughtbot.github.io/factory_bot/print

This snippet outlines the different build strategies supported by Factory Bot: `build`, `create`, `attributes_for`, and `build_stubbed`, with examples of their usage.

```ruby
# Returns a User instance that's not saved
user = build(:user)

# Returns a saved User instance
user = create(:user)

# Returns a hash of attributes, which can be used to build a User instance for example
attrs = attributes_for(:user)

# Integrates with Ruby 3.0's support for pattern matching assignment
attributes_for(:user) => {email:, name:, **attrs}

# Returns an object with all defined attributes stubbed out
stub = build_stubbed(:user)
```

--------------------------------

### Install factory_bot for Non-Rails Projects

Source: https://thoughtbot.github.io/factory_bot/setup/summary

Add the core factory_bot gem to your Gemfile if you are not using the Rails framework. This allows you to use factory_bot in other Ruby projects.

```ruby
gem "factory_bot"
```

--------------------------------

### Example Rake Task for Factory Bot Linting

Source: https://thoughtbot.github.io/factory_bot/print

Provides an example of how to integrate `FactoryBot.lint` into a Rake task, which is a recommended practice for running factory checks before the test suite executes to avoid performance impacts on individual tests.

```ruby
# Example Rake task:
task lint_factories: :environment do
  begin
    FactoryBot.lint
  rescue FactoryBot::InvalidFactoryError => e
    puts "Factories are invalid:"
    e.failures.each do |failure|
      puts "- #{failure.name}: #{failure.exception.message}"
    end
    exit(1)
  end
end
```

--------------------------------

### Set and Generate User Email Sequence Values

Source: https://thoughtbot.github.io/factory_bot/sequences/setting-the-value

Illustrates how to generate a user email sequence, including setting a specific starting number using `FactoryBot.set_sequence`.

```ruby
# user email
generate(:user, :with_email, :email) # "user_1@example.com"
FactoryBot.set_sequence(:user, :with_email, :email, 1_234_567)
generate(:user, :with_email, :email) # "user_1234567@example.com"
```

--------------------------------

### Define Sequence with Aliases and Default Counter

Source: https://thoughtbot.github.io/factory_bot/sequences/aliases

This example demonstrates defining a sequence with aliases but using the default starting value (1) for the counter. The aliases 'sender' and 'receiver' will share this counter.

```ruby
factory :user do
  sequence(:email, aliases: [:sender, :receiver]) { |n| "person#{n}@example.com" }
end
```

--------------------------------

### Configure factory_bot Definition File Paths

Source: https://thoughtbot.github.io/factory_bot/ref/find_definitions

The load order for factory definitions can be customized by setting the `FactoryBot.definition_file_paths`. This can be done during application initialization, for example, in `config/initializers`, or through `Rails.application.config.factory_bot.definition_file_paths`.

```Ruby
FactoryBot.definition_file_paths = [
  "path/to/your/factories",
  "another/path/**/*.rb"
]
```

```Ruby
Rails.application.config.factory_bot.definition_file_paths = [
  "config/factories",
  "app/models/factories/**/*.rb"
]
```

--------------------------------

### Define Sequence with Aliases and Custom Start Value

Source: https://thoughtbot.github.io/factory_bot/sequences/aliases

This snippet shows how to define a sequence named 'email' with aliases 'sender' and 'receiver'. It starts the counter at 1000 and provides a block to generate email addresses.

```ruby
factory :user do
  sequence(:email, 1000, aliases: [:sender, :receiver]) { |n| "person#{n}@example.com" }
end

# will increase value counter for :email which is shared by :sender and :receiver
generate(:sender)
```

--------------------------------

### Rewind All FactoryBot Sequences

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates rewinding all global and factory-specific sequences to their starting values using `FactoryBot.rewind_sequences`. This is useful for resetting sequence states between tests.

```ruby
FactoryBot.define do
  sequence(:email) {|n| "person#{n}@example.com" }

  factory :user do
    sequence(:email) {|n| "user#{n}@example.com" }
  end
end

generate(:email) # "person1@example.com"
generate(:email) # "person2@example.com"
generate(:email) # "person3@example.com"

generate(:user, :email) # "user1@example.com"
generate(:user, :email) # "user2@example.com"
generate(:user, :email) # "user3@example.com"

FactoryBot.rewind_sequences

generate(:email)        # "person1@example.com"
generate(:user, :email) # "user1@example.com"
```

--------------------------------

### Use Symbol#to_proc for Callbacks

Source: https://thoughtbot.github.io/factory_bot/print

This example illustrates using `Symbol#to_proc` as a shorthand for defining callbacks, particularly for simple methods like `confirm!` on a user object. This makes the factory definition more compact.

```ruby
# app/models/user.rb
class User < ActiveRecord::Base
  def confirm!
    # confirm the user account
  end
end

# spec/factories.rb
FactoryBot.define do
  factory :user do
    after :create, &:confirm!
  end
end

create(:user) # creates the user and confirms it
```

--------------------------------

### Define Factory Inline

Source: https://thoughtbot.github.io/factory_bot/using-without-bundler/summary

This example shows how to define factories directly within your code. It requires the gem and uses the `FactoryBot.define` block to create a factory for a 'user' object with specific attributes.

```ruby
require 'factory_bot'

FactoryBot.define do
  factory :user do
    name { 'John Doe' }
    date_of_birth { 21.years.ago }
  end
end
```

--------------------------------

### Define user factory with aliases

Source: https://thoughtbot.github.io/factory_bot/aliases/summary

Defines a 'user' factory with aliases 'author' and 'commenter' for simplified association usage. This factory includes attributes for first name, last name, and date of birth.

```ruby
factory :user, aliases: [:author, :commenter] do
  first_name { "John" }
  last_name { "Doe" }
  date_of_birth { 18.years.ago }
end
```

--------------------------------

### Define a factory with a sequence for email

Source: https://thoughtbot.github.io/factory_bot/sequences/initial-value

This snippet demonstrates how to define a factory for a 'user' with a sequence for the 'email' attribute. The sequence starts at 1000 and generates unique email addresses.

```ruby
factory :user do
  sequence(:email, 1000) { |n| "person#{n}@example.com" }
end
```

--------------------------------

### factory_bot Callbacks: Global, Factory, and Trait Order

Source: https://thoughtbot.github.io/factory_bot/callbacks/callback_order

Demonstrates the execution order of factory_bot callbacks including global, factory-specific, and trait-specific callbacks. This example highlights how callbacks are nested and executed based on their definition scope.

```ruby
FactoryBot.define do
  before(:all) { puts "Global before(:all)" }
  after(:all) { puts "Global after(:all)" }

  factory :user do
    before(:all) { puts "User before(:all)" }
    after(:all) { puts "User after(:all)" }
    before(:build) { puts "User before(:build)" }
    after(:build) { puts "User after(:build)" }

    trait :trait_a do
      before(:build) { puts "Trait-A before(:build)" }
      after(:build) { puts "Trait-A after(:build)" }
    end

    trait :trait_b do
      before(:build) { puts "Trait-B before(:build)" }
      after(:build) { puts "Trait-B after(:build)" }
    end
  end
end

build(:user, :trait_b, :trait_a)
```

--------------------------------

### Use alias for user association in post factory

Source: https://thoughtbot.github.io/factory_bot/aliases/summary

Demonstrates using the 'author' alias to associate a 'user' with a 'post' factory. This replaces the need for a full 'association' declaration.

```ruby
factory :post do
  # The alias allows us to write author instead of
  # association :author, factory: :user
  author
  title { "How to read a book effectively" }
  body { "There are five steps involved." }
end
```

--------------------------------

### Use alias for user association in comment factory

Source: https://thoughtbot.github.io/factory_bot/aliases/summary

Shows how to utilize the 'commenter' alias to associate a 'user' with a 'comment' factory, simplifying the association syntax.

```ruby
factory :comment do
  # The alias allows us to write commenter instead of
  # association :commenter, factory: :user
  commenter
  body { "Great article!" }
end
```

--------------------------------

### Selectively lint factories

Source: https://thoughtbot.github.io/factory_bot/linting-factories/summary

This example shows how to lint specific factories by filtering the available factories. Here, factories prefixed with 'old_' are excluded from the linting process.

```ruby
factories_to_lint = FactoryBot.factories.reject do |factory|
  factory.name =~ /^old_/
end

FactoryBot.lint factories_to_lint
```

--------------------------------

### Explicitly Specify Factory Class

Source: https://thoughtbot.github.io/factory_bot/print

This example shows how to explicitly define the class for a factory. This is useful when the factory name doesn't directly map to the desired class name.

```ruby
# This will use the User class (otherwise Admin would have been guessed)
factory :admin, class: "User"
```

--------------------------------

### Attribute Setter Example in Ruby

Source: https://thoughtbot.github.io/factory_bot/ref/add_attribute

Illustrates the direct use of a Ruby attribute setter, which is how `add_attribute` functions internally. This shows the assignment of a value to the 'name' attribute of a User object.

```ruby
user = User.new
user.name = "Acid Burn"
```

--------------------------------

### Generating a Single Sequence Value

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates the `generate` method for retrieving a single value from a sequence. This is the primary way to interact with sequences to get their next value.

```ruby
generate(:email)
# => "person1@example.com"

generate(:email)
# => "person2@example.com"
```

--------------------------------

### factory_bot Callbacks: Inheritance and Nested Traits Order

Source: https://thoughtbot.github.io/factory_bot/callbacks/callback_order

Illustrates the callback execution order in a more complex scenario involving factory inheritance and multiple nested traits. This example showcases how callbacks from global, parent, child factories, and various traits are sequenced.

```ruby
FactoryBot.define do
  before(:all) { puts "Global before(:all)" }
  before(:build) { puts "Global before(:build)" }
  after(:build) { puts "Global after(:build)" }
  after(:all) { puts "Global after(:all)" }

  factory :parent do
    before(:all) { puts "Parent before(:all)" }
    before(:build) { puts "Parent before(:build)" }
    after(:all) { puts "Parent after(:all)" }
    after(:build) { puts "Parent after(:build)" }

    trait :trait_a do
      before(:build) { puts "Trait-A before(:build)" }
      after(:build) { puts "Trait-A after(:build)" }
    end

    factory :child do
      before(:all) { puts "Child before(:all)" }
      before(:build) { puts "Child before(:build)" }
      after(:build) { puts "Child after(:build)" }
      after(:all) { puts "Child after(:all)" }

      trait :trait_b do
        before(:build) { puts "Trait-B before(:build)" }
        after(:build) { puts "Trait-B after(:build)" }
        after(:all) { puts "Trait-B after(:all)" }
      end

      trait :trait_c do
        before(:build) { puts "Trait-C before(:build)" }
        after(:build) { puts "Trait-C after(:build)" }
        before(:all) { puts "Trait-C before(:all)" }
      end
    end
  end
end

build(:child, :trait_c, :trait_a, :trait_b)
```

--------------------------------

### Overriding Attributes on Associations (Ruby)

Source: https://thoughtbot.github.io/factory_bot/print

Explains how to override attributes on associations, providing examples for implicit, explicit, and inline methods. This allows customization of associated objects.

```ruby
factory :post do
  # ...
  author factory: :author, last_name: "Writely"
end

factory :post do
  # ...
  association :author, last_name: "Writely"
end

factory :post do
  # ...
  author_last_name { "Writely" }
  author { association :author, last_name: author_last_name }
end

```

--------------------------------

### Linking Associated Objects with Attribute Overrides (Ruby)

Source: https://thoughtbot.github.io/factory_bot/print

Shows how attribute overrides can be used to link associated objects. This includes examples using direct association and overriding attributes of associated objects.

```ruby
FactoryBot.define do
  factory :author do
    name { 'Taylor' }
  end

  factory :post do
    author
  end
end

eunji = build(:author, name: 'Eunji')
post = build(:post, author: eunji)

```

```ruby
author = build(:author, name: 'Eunji')

post = build(:post, author:)

```

--------------------------------

### Sequence Incrementing Without a Block

Source: https://thoughtbot.github.io/factory_bot/print

Illustrates a sequence that automatically increments its value without needing a custom block. It starts from its initial value (defaulting to 1 if not specified) and increments on each call.

```ruby
factory :post do
  sequence(:position)
end
```

--------------------------------

### Manage Model Callbacks within Factory Definitions

Source: https://thoughtbot.github.io/factory_bot/callbacks/summary

This example demonstrates how to temporarily disable a model's 'after_create' callback before a factory is created and then re-enable it afterwards. This is useful for preventing unintended side effects during factory operations.

```ruby
factory :user do
  before(:all){ User.skip_callback(:create, :after, :send_welcome_email) }
  after(:all){ User.set_callback(:create, :after, :send_welcome_email) }
end
```

--------------------------------

### Generate Has-Many Data with Transient Attributes and Inline Associations

Source: https://thoughtbot.github.io/factory_bot/cookbook/has_many-associations

This example combines transient attributes with inline associations for more flexible generation of has-many relationships. The `user_with_posts` factory includes a `posts_count` transient attribute, and the `posts` association uses `Array.new` to create the specified number of associated posts. This method is versatile for use with `create`, `build`, and `build_stubbed`.

```ruby
FactoryBot.define do
  factory :post do
    title { "Through the Looking Glass" }
    user
  end

  factory :user do
    name { "Adiza Kumato" }

    factory :user_with_posts do
      transient do
        posts_count { 5 }
      end

      posts do
        Array.new(posts_count) { association(:post) }
      end
    end
  end
end

create(:user_with_posts).posts.length # 5
create(:user_with_posts, posts_count: 15).posts.length # 15
build(:user_with_posts, posts_count: 15).posts.length # 15
build_stubbed(:user_with_posts, posts_count: 15).posts.length # 15
```

--------------------------------

### Using Traits with Different Association Names in factory_bot

Source: https://thoughtbot.github.io/factory_bot/traits/with-associations

This example demonstrates using traits with associations where the association name differs from the factory name. It defines a user factory with an admin trait and a post factory associating with an 'author' that uses the user factory with the admin trait. Two syntaxes are shown for applying the trait.

```ruby
factory :user do
  name { "Friendly User" }

  trait :admin do
    admin { true }
  end
end

factory :post do
  association :author, :admin, factory: :user, name: 'John Doe'
  # or
  association :author, factory: [:user, :admin], name: 'John Doe'
end

# creates an admin user with name "John Doe"
create(:post).author
```

--------------------------------

### factory_bot Create Strategy

Source: https://thoughtbot.github.io/factory_bot/print

The `FactoryBot.create` method constructs an instance of the class and then persists it. It supports similar build strategies as `FactoryBot.build` (single, pair, list) and includes hooks for the creation process (`after_build`, `before_create`, `to_create`, `after_create`).

```ruby
FactoryBot.create(:user)
FactoryBot.create(:user, :admin, name: "John Doe")
FactoryBot.create_list(:user, 5)
FactoryBot.create_list(:user, 5, name: "Jane Doe")
FactoryBot.create_pair(:user)
```

--------------------------------

### Define a Factory with factory_bot

Source: https://thoughtbot.github.io/factory_bot/ref/factory

Demonstrates the basic syntax for defining a factory using `FactoryBot.define`. It shows how to specify the factory name and use a block to define its attributes. The `:class` option is used to specify the object the factory should build.

```ruby
FactoryBot.define do
  factory :user do
    name { "John Doe" }
    email { "john.doe@example.com" }
    
    factory :admin, class: "AdminUser" do
      role { "admin" }
    end
  end
end
```

--------------------------------

### Lint all factories with factory_bot

Source: https://thoughtbot.github.io/factory_bot/linting-factories/summary

This snippet demonstrates the basic usage of `FactoryBot.lint` to create each factory and catch exceptions. It's recommended to run this before your test suite.

```ruby
FactoryBot.lint
```

--------------------------------

### Custom Initialization with User.build_with_name

Source: https://thoughtbot.github.io/factory_bot/custom-construction/summary

Shows how to use `initialize_with` to call a custom class method, `User.build_with_name`, for object instantiation. This allows for more complex object creation logic beyond a simple `new` call.

```Ruby
factory :user do
  name { "John Doe" }

  initialize_with { User.build_with_name(name) }
end
```

--------------------------------

### Generate Data with FactoryBot

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates basic data generation using `generate` and `generate_list` for different attributes and types.

```ruby
generate(:char) # "global_character_a"
generate_list(:char, 2) # ["global_character_b", "global_character_c"]
generate(:char) # "global_character_d"

generate(:user, :name) # "Jane"
generate_list(:user, :name, 3) # ['Joe', 'Josh', 'Jayde']
generate(:user, :name) # "John"

generate(:user, :with_age, :age) # 21
generate_list(:user, :with_age, :age, 5) # [22, 23, 24, 25, 26]
generate(:user, :with_age, :age) # 27
```

--------------------------------

### FactoryBot Traits with Instance Creation

Source: https://thoughtbot.github.io/factory_bot/print

Explains how to pass traits as symbols during instance creation (build, create, etc.) to apply specific configurations and overrides.

```ruby
factory :user do
  name { "Friendly User" }

  trait :active do
    name { "John Doe" }
    status { :active }
  end

  trait :admin do
    admin { true }
  end
end

# creates an admin user with :active status and name "Jon Snow"
create(:user, :admin, :active, name: "Jon Snow")
```

```ruby
factory :user do
  name { "Friendly User" }

  trait :active do
    name { "John Doe" }
    status { :active }
  end

  trait :admin do
    admin { true }
  end
end

# creates 3 admin users with :active status and name "Jon Snow"
create_list(:user, 3, :admin, :active, name: "Jon Snow")
```

--------------------------------

### factory_bot Create Method

Source: https://thoughtbot.github.io/factory_bot/ref/build-strategies

Explains the `FactoryBot.create` method for constructing and persisting objects. It details the hooks invoked during creation (`after_build`, `before_create`, `to_create`, `after_create`) and how the `to_create` hook controls persistence, defaulting to `#save!`.

```ruby
user = UserFactory.create
admin = UserFactory.create(:admin)
user = UserFactory.create({ name: "John Doe" })
user = UserFactory.create(:admin, { name: "Jane Doe" })
user = UserFactory.create do |u|
  u.name = "John Doe"
end
users = UserFactory.create_list(5)
users = UserFactory.create_list(5, :admin)
users = UserFactory.create_list(5, { name: "John Doe" })
users = UserFactory.create_list(5, :admin, { name: "Jane Doe" })
users = UserFactory.create_list(5) do |u, i|
  u.name = "User #{i}"
end

UserFactory.to_create do |user_instance|
  user_instance.save
end
```

--------------------------------

### factory_bot Build Strategies

Source: https://thoughtbot.github.io/factory_bot/ref/build-strategies

Demonstrates how to construct instances using factory_bot's built-in build strategies like .build, .build_pair, and .build_list. These methods accept factory names, traits, and attribute overrides, and can also take a block for post-construction manipulation. They utilize ActiveSupport::Notifications for instrumentation.

```ruby
user = UserFactory.build
admin = UserFactory.build(:admin)
user = UserFactory.build({ name: "John Doe" })
user = UserFactory.build(:admin, { name: "Jane Doe" })
user = UserFactory.build do |u|
  u.name = "John Doe"
end
users = UserFactory.build_list(5)
users = UserFactory.build_list(5, :admin)
users = UserFactory.build_list(5, { name: "John Doe" })
users = UserFactory.build_list(5, :admin, { name: "Jane Doe" })
users = UserFactory.build_list(5) do |u, i|
  u.name = "User #{i}"
end
```

--------------------------------

### factory_bot: initialize_with default definition

Source: https://thoughtbot.github.io/factory_bot/ref/build-and-create

The `initialize_with` method defines how an object instance is created for a factory. It accepts a block that can access the factory's attributes and is used to return a new instance of the object.

```ruby
initialize_with { new }
```

--------------------------------

### Setting up Associations in Factories (Ruby)

Source: https://thoughtbot.github.io/factory_bot/print

Explains how to set up associations within factories. If the factory name matches the association name, the factory name can be omitted.

```ruby
factory :post do
  # ...
  author
end

```

--------------------------------

### Use FactoryBot callbacks for build strategies

Source: https://thoughtbot.github.io/factory_bot/print

Callbacks like `after`, `before`, and `callback` allow hooking into FactoryBot's build process. They can be scoped to a specific factory or global. Callbacks receive the factory instance and the context, including transient attributes.

```ruby
factory :user do
  after(:create) do |user, context|
    user.post_first_article(context.article)
  end

  callback(:after_create) do |user, context|
    user.post_first_article(context.article)
  end
end
```

--------------------------------

### Define Factory Bot Sequences and Factories

Source: https://thoughtbot.github.io/factory_bot/sequences/setting-the-value

Defines global sequences and factory sequences for 'user' with traits for email. This sets up the data structures for generating test data.

```ruby
FactoryBot.define do
  sequence(:char, 'a') {|c| "global_character_#{c}" }

  factory :user do
    sequence(:name, %w[Jane Joe Josh Jayde John].to_enum)

    trait :with_email do
      sequence(:email) {|n| "user_#{n}@example.com" }
    end
  end
end
```

--------------------------------

### Referencing Sequences by URI (Resource String)

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates referencing a sequence using a single string formatted as a URI, with names separated by forward slashes. This provides a concise way to specify the sequence.

```ruby
generate("my_factory_name/my_trait_name/my_sequence_name")
```

--------------------------------

### Using after and callback for after_create

Source: https://thoughtbot.github.io/factory_bot/ref/hooks

Demonstrates how to use the `after` and `callback` methods in factory_bot to execute code after a record is created. The `after` method provides a more concise syntax for common callbacks like `after(:create)`. Both methods accept a block that receives the created instance and a context object. The context can hold transient attributes passed during factory creation.

```ruby
after(:create) do |user, context|
  user.post_first_article(context.article)
end

callback(:after_create) do |user, context|
  user.post_first_article(context.article)
end
```

--------------------------------

### factory_bot Build Strategy

Source: https://thoughtbot.github.io/factory_bot/print

The `FactoryBot.build` method constructs an instance of the class. It can build single instances, pairs, or lists of instances. It also supports traits, overrides, and blocks for further customization.

```ruby
FactoryBot.build(:user)
FactoryBot.build(:user, :admin, name: "John Doe")
FactoryBot.build_list(:user, 5)
FactoryBot.build_list(:user, 5, name: "Jane Doe")
FactoryBot.build_pair(:user)
```

--------------------------------

### Global initialize_with for All Factories

Source: https://thoughtbot.github.io/factory_bot/custom-construction/summary

Demonstrates how to set a default `initialize_with` behavior for all factories defined within a `FactoryBot.define` block. This is useful for applying consistent instantiation logic across your project.

```Ruby
FactoryBot.define do
  initialize_with { new("Awesome first argument") }
end
```

--------------------------------

### Register custom FactoryBot build strategies

Source: https://thoughtbot.github.io/factory_bot/print

Add new build strategies by calling `FactoryBot.register_strategy`. The provided class must implement `association` and `result` methods. `association` handles building associated records, and `result` returns the final object.

```ruby
class MyStrategy
  def self.call(runner)
    # Build logic
    runner.run(:build)
  end

  def self.association(runner)
    runner.run(:build)
  end

  def self.result(object)
    object
  end
end

FactoryBot.register_strategy(:my_strategy, MyStrategy)
```

--------------------------------

### Define and Generate Sequences in factory_bot

Source: https://thoughtbot.github.io/factory_bot/sequences/generating

Demonstrates defining sequences for characters and user attributes (name, age) and then generating single values or lists of these sequences using `generate` and `generate_list`.

```ruby
FactoryBot.define do
  sequence(:char, 'a') {|c| "global_character_#{c}" }

  factory :user do
    sequence(:name, %w[Jane Joe Josh Jayde John].to_enum)

    trait :with_age do
      sequence(:age, 21)
    end
  end
end

##
# char
generate(:char) # "global_character_a"
generate_list(:char, 2) # ["global_character_b", "global_character_c"]
generate(:char) # "global_character_d"

##
# user name
generate(:user, :name) # "Jane"
generate_list(:user, :name, 3) # ['Joe', 'Josh', 'Jayde']
generate(:user, :name) # "John"

##
# user age
generate(:user, :with_age, :age) # 21
generate_list(:user, :with_age, :age, 5) # [22, 23, 24, 25, 26]
generate(:user, :with_age, :age) # 27
```

--------------------------------

### Factory Options in factory_bot

Source: https://thoughtbot.github.io/factory_bot/ref/factory

Illustrates how to configure factory behavior using options like `:parent`, `:aliases`, and `:traits`. The `:parent` option allows for inheritance, `:aliases` provide alternative names for a factory, and `:traits` define reusable sets of attributes.

```ruby
FactoryBot.define do
  factory :post, parent: :published_post, aliases: [:article] do
    title { "My First Post" }
    
    trait :draft do
      published_at { nil }
    end
  end
end
```

--------------------------------

### factory_bot: to_create default definition

Source: https://thoughtbot.github.io/factory_bot/ref/build-and-create

The `to_create` method customizes the `FactoryBot.create` strategy. It takes a block that receives the constructed object and the factory_bot context, allowing control over persistence, with the default being to save the object.

```ruby
to_create { |obj, context| obj.save! }
```

--------------------------------

### Set and Generate User Name Sequence Values

Source: https://thoughtbot.github.io/factory_bot/sequences/setting-the-value

Shows how to generate a user name sequence and then set it to a specific value using `FactoryBot.set_sequence`.

```ruby
# user name
generate(:user, :name) # "Jane"
FactoryBot.set_sequence(:user, :name, 'Jayde')
generate(:user, :name) # "Jayde"
```

--------------------------------

### Referencing Sequences by URI (Strings)

Source: https://thoughtbot.github.io/factory_bot/print

Illustrates referencing a sequence by providing its constituent names (factory, trait, sequence) as individual strings to the `generate` method.

```ruby
generate('my_factory_name', 'my_trait_name', 'my_sequence_name')
```

--------------------------------

### Define Factories and Build Objects with Overrides (Ruby)

Source: https://thoughtbot.github.io/factory_bot/associations/association-overrides

Demonstrates defining factories for 'author' and 'post' and then building instances with attribute overrides. Shows how to link associated objects.

```Ruby
FactoryBot.define do
  factory :author do
    name { 'Taylor' }
  end

  factory :post do
    author
  end
end

eunji = build(:author, name: 'Eunji')
post = build(:post, author: eunji)

```

--------------------------------

### Referencing Sequences by URI (Symbols)

Source: https://thoughtbot.github.io/factory_bot/print

Shows how to reference a sequence using its factory name, trait name (if applicable), and sequence name, all provided as individual symbols to the `generate` method.

```ruby
generate(:my_factory_name, :my_trait_name, :my_sequence_name)
```

--------------------------------

### factory_bot Build Strategies: build, create, attributes_for, build_stubbed

Source: https://thoughtbot.github.io/factory_bot/using-factories/build-strategies

Demonstrates the usage of factory_bot's core build strategies. `build` creates an unsaved instance, `create` saves an instance to the database, `attributes_for` returns a hash of attributes, and `build_stubbed` creates an object with stubbed attributes. Blocks can be passed to yield the created object for further manipulation.

```ruby
user = build(:user)

user = create(:user)

attrs = attributes_for(:user)

attributes_for(:user) => {email:, name:, **attrs}

stub = build_stubbed(:user)

create(:user) do |user|
  user.posts.create(attributes_for(:post))
end
```

--------------------------------

### Sequence with Enumerable and Cycle

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates using an Enumerable (an array of symbols) with the `.cycle` method as the source for a sequence. This allows generating values by cycling through a predefined list.

```ruby
factory :task do
  sequence :priority, %i[low medium high urgent].cycle
end
```

--------------------------------

### Registering a Build Strategy with factory_bot

Source: https://thoughtbot.github.io/factory_bot/ref/register_strategy

Demonstrates how to add a new build strategy to factory_bot. The `register_strategy` method accepts a symbol for the strategy name and a class that defines `association` and `result` methods.

```ruby
FactoryBot.register_strategy(:my_strategy, MyStrategyClass)
```

--------------------------------

### Initializing with Attributes Hash using **attributes

Source: https://thoughtbot.github.io/factory_bot/custom-construction/summary

Illustrates how to pass all defined factory attributes, excluding transient ones, to the constructor using `new(**attributes)`. This is a convenient way to initialize objects with multiple attributes.

```Ruby
factory :user do
  transient do
    comments_count { 5 }
  end

  name "John Doe"

  initialize_with { new(**attributes) }
end
```

--------------------------------

### Define Global Callbacks

Source: https://thoughtbot.github.io/factory_bot/print

Shows how to define callbacks that apply globally to all factories by placing them within a `FactoryBot.define` block. These global callbacks execute before or after factory-specific or trait callbacks.

```ruby
FactoryBot.define do
  after(:build) { |object| puts "Built #{object}" }
  after(:create) { |object| AuditLog.create(attrs: object.attributes) }

  factory :user do
    name { "John Doe" }
  end
end
```

--------------------------------

### Custom Object Initialization with `initialize_with`

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates overriding the default object initialization behavior using `initialize_with`. This is useful for non-ActiveRecord objects that require arguments in their `initialize` method.

```ruby
# user.rb
class User
  attr_accessor :name, :email

  def initialize(name)
    @name = name
  end
end

# factories.rb
sequence(:email) { |n| "person#{n}@example.com" }

factory :user do
  name { "Jane Doe" }
  email

  initialize_with { new(name) }
end

build(:user).name # Jane Doe
```

--------------------------------

### Create with Block - FactoryBot

Source: https://thoughtbot.github.io/factory_bot/print

Demonstrates creating an instance of a factory and yielding the created object to a block for further modifications. This allows for nested object creation or attribute setting within the yielded object.

```ruby
create(:user) do |user|
  user.posts.create(attributes_for(:post))
end
```

--------------------------------

### Optimized Initialization with initialize_with (No Duplicate Assignment)

Source: https://thoughtbot.github.io/factory_bot/custom-construction/summary

Explains how `initialize_with` prevents duplicate assignment by only passing attributes to the constructor. This behavior is demonstrated with a `User` factory, showing the optimized instantiation flow compared to older versions.

```Ruby
FactoryBot.define do
  factory :user do
    initialize_with { new(name) }

    name { 'value' }
  end
end

build(:user)
# runs
User.new('value')
```

--------------------------------

### FactoryBot Sequences with Scopes

Source: https://thoughtbot.github.io/factory_bot/print

Illustrates how to use sequences with scopes to ensure proper value generation, especially when attributes depend on other factory attributes or external objects.

```ruby
FactoryBot.define do
  factory :user do
    sequence(:email) { |n| "#{name}-#{n}@example.com" }
  end
end

jester = build(:user, name: "Jester")
jester.email # "Jester-1@example.com"

generate(:user, :email, scope: jester)
# "Jester-2@example.com"

generate_list(:user, :email, 2, scope: jester)
# ["Jester-3@example.com", "Jester-4@example.com"]
```

```ruby
require 'ostruct'

FactoryBot.define do
  factory :user do
    sequence(:info) { |n| "#{name}-#{n}-#{age + n}" }
  end
end

test_scope = OpenStruct.new(name: "Jester", age: 23)

generate_list('user/info', 3, scope: test_scope)
# ["Jester-1-24", "Jester-2-25", "Jester-3-26"]
```

--------------------------------

### Define Factory with after(:build) Callback

Source: https://thoughtbot.github.io/factory_bot/callbacks/summary

This snippet shows how to define a factory named 'user' that executes a 'generate_hashed_password' method after the user object is built. The 'after(:build)' callback receives the built object and a context object.

```ruby
factory :user do
  after(:build) { |user, context| generate_hashed_password(user) }
end
```

--------------------------------

### Create Multiple Factory Instances (build_list, create_list)

Source: https://thoughtbot.github.io/factory_bot/building-or-creating-multiple-records/summary

Use build_list and create_list to generate multiple factory instances. You can pass a hash to set attributes for all instances or a block to customize each instance individually. `create_list` saves instances before yielding them.

```Ruby
built_users   = build_list(:user, 25)
created_users = create_list(:user, 25)
```

```Ruby
twenty_year_olds = build_list(:user, 25, date_of_birth: 20.years.ago)
```

```Ruby
twenty_somethings = build_list(:user, 10) do |user, i|
  user.date_of_birth = (20 + i).years.ago
end
```

```Ruby
twenty_somethings = create_list(:user, 10) do |user, i|
  user.date_of_birth = (20 + i).years.ago
  user.save!
end
```

--------------------------------

### Nesting Factories for Reusability (Ruby)

Source: https://thoughtbot.github.io/factory_bot/print

Illustrates how to create multiple factories for the same class without repeating common attributes by nesting factories. This promotes code reuse and organization.

```ruby
factory :post do
  title { "A title" }

  factory :approved_post do
    approved { true }
  end
end

approved_post = create(:approved_post)
approved_post.title    # => "A title"
approved_post.approved # => true

```

--------------------------------

### Define and Register Custom Strategy with Callbacks (Ruby)

Source: https://thoughtbot.github.io/factory_bot/custom-callbacks/summary

Demonstrates how to create a custom strategy named 'json' that includes before, after, and custom callbacks. It registers this strategy with FactoryBot and defines a factory that utilizes these callbacks.

```ruby
class JsonStrategy
  def initialize
    @strategy = FactoryBot.strategy_by_name(:create).new
  end

  delegate :association, to: :@strategy

  def result(evaluation)
    result = @strategy.result(evaluation)
    evaluation.notify(:before_json, result)

    result.to_json.tap do |json|
      evaluation.notify(:after_json, json)
      evaluation.notify(:make_json_awesome, json)
    end
  end

  def to_sym
    :json
  end
end

FactoryBot.register_strategy(:json, JsonStrategy)

FactoryBot.define do
  factory :user do
    before(:json)                { |user| do_something_to(user) }
    after(:json)                 { |user_json| do_something_to(user_json) }
    callback(:make_json_awesome) { |user_json| do_something_to(user_json) }
  end
end
```

--------------------------------

### factory_bot Null Method

Source: https://thoughtbot.github.io/factory_bot/ref/build-strategies

Explains the `FactoryBot.null` method, which returns `nil`. It also covers `null_pair` for a pair of nils and `null_list` for multiple nils, noting its internal usage.

```ruby
nil_value = FactoryBot.null
nil_pair = FactoryBot.null_pair
nil_list = FactoryBot.null_list(3)
```

--------------------------------

### Generate Has-Many Data with Plain Ruby Helper

Source: https://thoughtbot.github.io/factory_bot/cookbook/has_many-associations

This method uses a plain Ruby helper to create associated records. It defines factories for 'post' and 'user' and then a helper function 'user_with_posts' to create a user and a specified number of posts associated with that user. It's a straightforward way to set up relationships.

```ruby
FactoryBot.define do
  factory :post do
    title { "Through the Looking Glass" }
    user
  end

  factory :user do
    name { "Rachel Sanchez" }
  end
end

def user_with_posts(posts_count: 5)
  FactoryBot.create(:user) do |user|
    FactoryBot.create_list(:post, posts_count, user: user)
  end
end

create(:user).posts.length # 0
user_with_posts.posts.length # 5
user_with_posts(posts_count: 15).posts.length # 15
```

--------------------------------

### Customize Factory Definition Paths

Source: https://thoughtbot.github.io/factory_bot/using-without-bundler/summary

This snippet illustrates how to specify custom directories for factory definitions if they are not in the default locations. After setting the paths, `find_definitions` will load from the specified directories.

```ruby
FactoryBot.definition_file_paths = %w(custom_factories_directory)
FactoryBot.find_definitions
```

--------------------------------

### Define Multiple Callback Types - factory_bot

Source: https://thoughtbot.github.io/factory_bot/callbacks/multiple-callbacks

Demonstrates how to define different types of callbacks (after build and after create) on the same factory. This allows for specific actions to be performed after object instantiation and after object persistence.

```ruby
factory :user do
  after(:build)  { |user| do_something_to(user) }
  after(:create) { |user| do_something_else_to(user) }
end
```

--------------------------------

### Load factory_bot Definitions

Source: https://thoughtbot.github.io/factory_bot/ref/find_definitions

The `FactoryBot.find_definitions` method is used to load all factory definitions within a project. The order in which these definitions are loaded is determined by the `FactoryBot.definition_file_paths` attribute, which can be configured.

```Ruby
FactoryBot.find_definitions
```

--------------------------------

### Basic Factory Definition for User

Source: https://thoughtbot.github.io/factory_bot/print

This is a simple Factory Bot definition for a 'user' factory. It sets attributes like first name, last name, and admin status.

```ruby
# This will guess the User class
FactoryBot.define do
  factory :user do
    first_name { "John" }
    last_name  { "Doe" }
    admin { false }
  end
end
```

--------------------------------

### Set and Generate Global Sequence Values

Source: https://thoughtbot.github.io/factory_bot/sequences/setting-the-value

Demonstrates how to generate a global sequence value and then set it to a specific value using `FactoryBot.set_sequence`.

```ruby
# char
generate(:char) # "global_character_a"
FactoryBot.set_sequence(:char, 'z')
generate(:char) # "global_character_z"
```

--------------------------------

### Define Multiple Callbacks for Multiple Strategies - factory_bot

Source: https://thoughtbot.github.io/factory_bot/callbacks/multiple-callbacks

Illustrates defining multiple callbacks for various strategies (stub, create, custom) within a single factory definition. This is useful for executing common code across different building strategies.

```ruby
factory :user do
  callback(:after_stub, :before_create) { do_something }
  after(:stub, :create) { do_something_else }
  before(:create, :custom) { do_a_third_thing }
end
```

--------------------------------

### Directly Generate Sequence Values

Source: https://thoughtbot.github.io/factory_bot/print

Explains how to directly generate single values or arrays of sequential values using `:generate` and `:generate_list` without building a full object. This speeds up testing by focusing only on sequence generation.

```ruby
FactoryBot.define do
  sequence(:char, 'a') {|c| "global_character_#{c}" }

  factory :user do
    sequence(:name, %w[Jane Joe Josh Jayde John].to_enum)

    trait :with_age do
      sequence(:age, 21)
    end
  end
end
```

--------------------------------

### Callback Execution Order with Global, Factory, and Trait Callbacks

Source: https://thoughtbot.github.io/factory_bot/print

This snippet details the execution order of callbacks when multiple are defined at different levels (global, factory, trait). It demonstrates how `before` and `after` callbacks are interleaved, respecting the hierarchy and order of trait application.

```ruby
FactoryBot.define do
  before(:all) { puts "Global before(:all)" }
  after(:all) { puts "Global after(:all)" }

  factory :user do
    before(:all) { puts "User before(:all)" }
    after(:all) { puts "User after(:all)" }
    before(:build) { puts "User before(:build)" }
    after(:build) { puts "User after(:build)" }

    trait :trait_a do
      before(:build) { puts "Trait-A before(:build)" }
      after(:build) { puts "Trait-A after(:build)" }
    end

    trait :trait_b do
      before(:build) { puts "Trait-B before(:build)" }
      after(:build) { puts "Trait-B after(:build)" }
    end
  end
end

build(:user, :trait_b, :trait_a)

# Result:
#
# 1. "Global before(:all)"
# 2. "User before(:all)"
# 3. "User before(:build)
# 4. "Trait-B before(:build)"
# 5. "Trait-A before(:build)"
# 6. "User after(:build)"
# 7. "Trait-B after(:build)"
# 8. "Trait-A after(:build)"
# 9. "Global after(:all)"
# 10. "User after(:all)"
```

--------------------------------

### Basic User Initialization with initialize_with

Source: https://thoughtbot.github.io/factory_bot/custom-construction/summary

Demonstrates overriding the default `new` behavior to pass the `name` attribute to the `User` class's `initialize` method. This is useful for non-ActiveRecord objects requiring constructor arguments.

```Ruby
class User
  attr_accessor :name, :email

  def initialize(name)
    @name = name
  end
end

sequence(:email) { |n| "person#{n}@example.com" }

factory :user do
  name { "Jane Doe" }
  email

  initialize_with { new(name) }
end

build(:user).name # Jane Doe
```
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