Generating randomized test data in Rails with Faker

Yesterday we discussed spinning up test data with FactoryBot. Today we'll expand upon that idea by using Faker, a gem with all sorts of whimsical modules for easily creating randomized data.

Faker's API

Faker has a ton of modules for generating data, all of which can be invoked with an API like Faker::Module.method. For example, the Name module can be used to generate, well, names of course:

> Faker::Name.first
> "Shirley"
> Faker::Name.last
> "Ernser"

Combining with FactoryBot

Let's update our user factory that we discussed yesterday to use Faker::Name to generate random user names. Here's the factory with a hardcoded default user name:

FactoryBot.define do
  factory :user do
    sequence(:email) { |n| "test#{n}@example.com" }
    password { "password" }
    first_name { "John" }
    last_name { "Dorian" }
  end
end

Here's the factory leveraging Faker:

FactoryBot.define do
  factory :user do
    sequence(:email) { |n| "test#{n}@example.com" }
    password { "password" }
    first_name { Faker::Name.first_name }
    last_name { Faker::Name.last_name }
  end
end

Generating unique values

Have an attribute that needs to be unique? Yesterday we talked about achieving this using FactoryBot sequences (as seen above for the email attribute), but what if we want our Faker data to be unique?

Faker provides a unique method that guarantees a random result (caveat: it can run out of unique results).

Faker::Name.unique.name # This will return a unique name every time it is called

More than just names

First and last names are just the beginning. Faker has a lot of modules for generating fake data.

There are modules for addresses, lorem ipsum, phone numbers, mountains, and more! Whatever you need, Faker is likely to have you covered.

Delightful whimsy

Faker isn't all business. Are you a Tolkien fan like me? You did see the painting of The Shire behind me in my headshot, didn't you?

Faker::Movies::LordOfTheRings.character #=> "Legolas"
Faker::Movies::LordOfTheRings.location #=> "Helm's Deep"

Conclusion

That wraps up for today. I hope you give Faker a spin and see if you enjoy working with it. Tomorrow we'll talk about a gem that adds some useful one-line tests to your arsenal for testing all sorts of things in your ActiveRecord models.