FactoryBot Rails

FactoryBot is a Ruby library for setting up Ruby objects as test data in a test suite. Specifically, FactoryBot Rails is an extension of FactoryBot designed to work seamlessly with Ruby on Rails applications.

In the context of testing Rails applications, FactoryBot Rails provides a convenient way to define and create factories for ActiveRecord models.

Factories are used to generate instances of model objects with predefined attributes, making it easier to set up test data for various scenarios.

---

Add to the Gemfile

According to the documentation, add factory_bot_rails to your Gemfile in both the test and development groups:

group :development, :test do
  gem 'rspec-rails'
  gem 'factory_bot_rails'
  gem "debug", platforms: %i[ mri mingw x64_mingw ]
end

---

Install the dependencies

bundle install

Output

---

Configure FactoryBot Rails

The next parts is to configure FactoryBotRails.

---

Create a folder

 mkdir spec/support

---

Create the configuration file

touch spec/support/factory_bot.rb

---

Add the configuration

# spec/support/factory_bot.rb
RSpec.configure do |config|
  config.include FactoryBot::Syntax::Methods
end

This configures RSpec to include FactoryBot methods (like create, build, etc.) in your tests and ensures that FactoryBot factories are loaded before the test suite runs.

---

Let's test

---

Create a rspec test file

 rails generate rspec:model Author

---

Use the create method

We don't have any factories yet, but let's try to use the create method anyway.

# spec/models/author_spec.rb
require 'rails_helper'

RSpec.describe Author, type: :model do  
  it 'creates a valid author object using FactoryBot' do    
    author = FactoryBot.create(:author)

    expect(author).to be_valid
    expect(author.persisted?).to eq(true)
  end
end

---

Run the tests

bundle exec rspec spec/models/author_spec.rb -fd

output

Great, it tried to create an object using FactoryBot.

---

Use the build method

# spec/models/author_spec.rb
RSpec.describe Author, type: :model do  
    it 'builds a valid author object using FactoryBot' do    
        author = FactoryBot.build(:author, name: 'John Doe')

        expect(author).to be_valid

        author.save

        expect(author.persisted?).to eq(true)
    end
end

Output of the complete code

---

Run the tests

bundle exec rspec spec/models/author_spec.rb -fd

Output

---

Create a factory

---

Create the factories folder

mkdir spec/factories

Output

---

Create the file

touch spec/factories/authors.rb

Output

---

Add the factory

# spec/factories/authors.rb
FactoryBot.define do
  factory :author do
    name { 'Toby Flanderson' }
  end
end

---

Run the tests

The error messages so far have indicated that we don't have registered factories, but this time we do.

Let's run the tests; all the tests should fail.

---

Run

bundle exec rspec spec/models/author_spec.rb -fd

Output

---

Done

---

---

Reach me out

• Github

• LinkedIn

• Hashnode

• Youtube

---

Final thoughts

Thank you for reading this article.

If you have any questions, thoughts, suggestions, or corrections, please share them with us.

We appreciate your feedback and look forward to hearing from you.