testing-factory_bot

FactoryBot Standards

Use FactoryBot rather than fixtures in Rails tests. Install the factory_bot gem if it is not already included in the Gemfile.

Factory Organization

1. Directory Structure

test/factories/
├── users.rb
├── posts.rb
├── comments.rb
└── traits/
    ├── addressable.rb
    └── timestampable.rb

1. Basic Factory Structure

# test/factories/users.rb
FactoryBot.define do
  factory :user do
    first_name { Faker::Name.first_name }
    last_name { Faker::Name.last_name }
    email { Faker::Internet.email }
    password { "password123" }

    trait :admin do
      role { "admin" }
      admin_since { Time.current }
    end

    trait :inactive do
      active { false }
      deactivated_at { Time.current }
    end

    factory :admin_user do
      role { "admin" }
      admin_since { Time.current }
    end
  end
end

Best Practices

1. Factory Design

• Keep factories minimal
• Use traits for variations
• Use sequences for unique values
• Follow database constraints

1. Naming Conventions

• Use singular form for factory names
• Use descriptive trait names
• Prefix dynamic values with with_
• Use verb past tense for states

1. Data Generation

• Use Faker for realistic data
• Use sequences for unique fields
• Use associations when needed
• Keep data consistent

1. Performance

• Avoid unnecessary associations
• Use build instead of create when possible
• Use traits to minimize database hits
• Clean up test data properly

Common Patterns

1. Associations

# test/factories/posts.rb
FactoryBot.define do
  factory :post do
    association :user
    title { Faker::Lorem.sentence }
    content { Faker::Lorem.paragraphs(number: 3).join("\n\n") }

    trait :with_comments do
      after(:create) do |post|
        create_list(:comment, 3, post: post)
      end
    end

    trait :published do
      published_at { Time.current }
      status { "published" }
    end
  end
end

# test/factories/comments.rb
FactoryBot.define do
  factory :comment do
    association :user
    association :post
    content { Faker::Lorem.paragraph }
  end
end