Chapter I - Introduction to RSpec

(avr. time for this chapter: 1 day)

Testing is a crucial part of software development. In the Ruby on Rails ecosystem, RSpec is one of the most popular testing frameworks. It provides a behavior-driven development (BDD) approach that makes tests readable and maintainable.

In this chapter, the objective is to understand the basics of RSpec, how to set it up in your ebook application, and how to write your first tests.

RSpec Setup

Before writing tests, you need to set up RSpec in your Rails application.

Steps to implement:

1. Add the rspec-rails gem to your Gemfile (in the :development and :test groups)
2. Run bundle install
3. Initialize RSpec with rails generate rspec:install
4. Understand the folder structure created:
5. spec/ - main folder for all tests
6. spec/spec_helper.rb - RSpec configuration
7. spec/rails_helper.rb - Rails-specific configuration
8. .rspec - command line options

Reference: RSpec Rails Documentation

Basic Test Structure

Understand the anatomy of an RSpec test file:

• describe blocks - group related tests
• context blocks - describe different scenarios
• it blocks - individual test cases
• expect - make assertions

Steps to implement:

1. Generate the spec file for your Ebook model: rails generate rspec:model Ebook
2. Open spec/models/ebook_spec.rb and examine the generated structure
3. Write your first test checking if the model can be instantiated
4. Run tests with bundle exec rspec

RSpec Matchers

Matchers are used to define expected outcomes. Practice with your Ebook and User models.

Steps to implement:

1. Practice using equality matchers: eq, eql, equal, be
2. Example: expect(ebook.status).to eq('draft')
3. Practice using comparison matchers: be >, be <, be_between
4. Example: expect(ebook.price).to be > 0
5. Practice using truthiness matchers: be_truthy, be_falsy, be_nil
6. Example: expect(user.enabled?).to be_truthy
7. Practice using collection matchers: include, match_array, contain_exactly
8. Example: expect(Ebook.statuses.keys).to include('draft', 'pending', 'live')
9. Practice using predicate matchers: be_empty, be_valid
10. Example: expect(ebook).to be_valid

Reference: RSpec Built-in Matchers

Hooks: before and after

Hooks allow you to run code before or after tests.

Steps to implement:

1. Use before(:each) to set up an ebook for each test:

   before(:each) do
     @ebook = Ebook.new(title: "Ruby Guide", price: 19.99)
   end
   

2. Use before(:all) to set up data once for all tests in a group
3. Understand when to use after hooks for cleanup
4. Practice using let and let! for lazy and eager evaluation:

   let(:user) { User.create(name: "John", email: "john@example.com") }
   let(:ebook) { Ebook.create(title: "Rails Tutorial", seller: user) }
   

Exercise

Apply these concepts to your ebook application:

1. Set up RSpec in your ebook application (if not already done)
2. Generate spec files for your existing models:
3. rails generate rspec:model Ebook
4. rails generate rspec:model User
5. Write basic model specs for your Ebook model:
6. Test that an ebook can be created with valid attributes (title, price, seller)
7. Test that an ebook without a title is invalid
8. Test the status enum values (Draft, Pending, Live)
9. Write basic model specs for your User model:
10. Test that a user can be created with name and email
11. Test the enable/disable status functionality