Fixture and factory usage in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a fixture in Rails testing?

A fixture is a fixed set of sample data stored in YAML files that Rails loads into the test database before running tests. It helps tests run with known data.

beginner

What is a factory in Rails testing?

A factory is a Ruby object that builds test data dynamically. It creates objects with default or customized attributes when tests run, often using Factory Bot.

intermediate

How do fixtures and factories differ in flexibility?

Fixtures use static data loaded before tests, so they are less flexible. Factories create data on demand with customizable attributes, making them more flexible for varied test cases.

beginner

How do you define a simple factory for a User model using Factory Bot?

You define it like this:

FactoryBot.define do
  factory :user do
    name { "Test User" }
    email { "[e-mail]" }
  end
end

intermediate

Why might you choose factories over fixtures in Rails tests?

Factories allow creating fresh, customized data for each test, reducing dependencies and making tests easier to maintain and understand. Fixtures can become brittle with static data.

What file format do Rails fixtures use to store test data?

A YAML

B JSON

C XML

D CSV

Rails fixtures are stored in YAML files, which are easy to read and write.

Which gem is commonly used to create factories in Rails?

A Factory Bot

B Pry

C Capybara

D RSpec

Factory Bot is the popular gem for defining and using factories in Rails tests.

Which is a benefit of using factories over fixtures?

A Static data for all tests

B Faster test runs always

C Dynamic, customizable test data

D No need to write any code

Factories create dynamic data with customizable attributes, unlike static fixtures.

How do you access fixture data in a Rails test?

A Using instance variables

B Using fixture names as methods

C Using FactoryBot.create

D Using SQL queries

Fixtures are accessed by their names as methods inside tests, e.g., users(:one).

Which statement about fixtures is true?

A They generate data at runtime dynamically

B They cannot be used with Rails

C They require Factory Bot to work

D They are loaded once before tests run

Fixtures load static data into the test database before tests run.

Explain the difference between fixtures and factories in Rails testing.

Think about how test data is created and used.

Describe how you would define and use a factory for a User model in a Rails test.

Focus on the syntax and usage steps.