Generating Test Data with Faker and friends

During my recent endeavours to build a REST API, I wanted to test the bulk upload feature of the API which required a large set of test data. I was looking for a quick way to create a fake test data set and found an interesting Ruby library called Faker. This a port of Perl’s Data::Faker library.

Faker is a popular choice in Rails community. It is also ported to Java, Python and JavaScript.

Faker provides a number of categories for test data generation. For example Names, Addresses, Pictures, Business & Finance (Credit Card Numbers, IBAN numbers, Swift Codes etc.), Text placeholders and much more.

Let’s say we want to create a list of records on the fly. We want a list of names and contact phone number. In Ruby, all we would have to do is:

First install Faker Gem with:

gem install faker

and create a simple script to generate records:

require 'faker'
require 'json'

landlords = []

100.times do
  landlord = Hash.new
  landlord["name"] = Faker::Name.name
  landlord["contact_number"] = Faker::PhoneNumber.cell_phone
  landlords.push(landlord)
end

puts JSON.pretty_generate(landlords)

This will create records similar to below output. You can copy or store the output and use it seed to database or during the testing

[
  {
    "name": "Ms. Adelia Ortiz",
    "contact_number": "1-443-107-3897"
  },
  {
    "name": "Delores Cassin",
    "contact_number": "868.775.6054"
  },
  {
    "name": "Rose Klocko",
    "contact_number": "759-090-9777"
  },
  {
    "name": "Josiah Langworth I",
    "contact_number": "1-308-497-4606"
  },
  {
    "name": "Kattie Hamill",
    "contact_number": "266-980-1233"
  },
]

We can also use Faker in automated tests. For example here’s Capybara test using a fake user data to test Sign-Up feature:

name = Faker::Name.name
email =  Faker::Internet.email

visit("/signup")

fill_in('account_name', with: name)
fill_in('account_email', with: email)
click_button('Sign Up')

page.has_content?("Dear ${name}")
page.has_content?('Verify Your Email Address')

Here’s JavaScript version of the Ruby script made with Faker.js

var faker = require('faker')

landlords = []
for(i=0; i<100; i++) {
  var user = {
    name: faker.name.findName(),
    email: faker.phone.phoneNumber(),
  };
  landlords.push(user)
}

console.log(landlords);

By default, these libraries generate values which may not be unique. However, you can set options to generate unique values. You can also extend/customise the output.

You can find Java port of the Faker called Java Faker
There is also Python port available at https://github.com/joke2k/faker

Faker and friends are must have power tool for Developers and testers.