Model Testing in Sinatra

Warmup

• Read the Thoughtbot article linked in the lesson plan.

Intro to RSpec

• describe blocks
• nested describe blocks
• it blocks
• expect instead of assert

Setup

• Add gem 'rspec' to your Gemfile.
• bundle

Create RSpec Directories and Files

• Create a .rspec file
• Create a spec directory
• Create a spec/spec_helper.rb file
• Create a spec/models directory
• Create a spec/models/horse_spec.rb file

RSpec Flags

Add to your .rspec file

• -–color
• -–format=documentation
• –order=random

Set Up Your Spec Helper

require 'bundler'
bundler.require(:default, :test)
require File.expand_path('../../config/environment.rb', __FILE__)

Set Up Your First Test

RSpec.describe Film do
  describe "Class Methods" do
    describe ".total_box_office_sales" do
      it "returns total box office sales for all films" do
        Film.create(title: "Fargo", year: 2017, box_office_sales: 3)
        Film.create(title: "Die Hard", year: 2016, box_office_sales: 4)

        expect(Film.total_box_office_sales).to eq(7)
      end
    end
  end
end

Implement the Method

# film.rb
def self.total_box_office_sales
  sum(:box_office_sales)
end

Update Spec Helper

On the first line:

ENV['RACK_ENV'] = 'test'

Run Migrations on Your Test DB

$ rake db:test:prepare

Add Database Cleaner

# Gemfile
gem 'database_cleaner'

# spec_helper.rb

require 'database_cleaner'

DatabaseCleaner.strategy = :truncation

RSpec.configure do |c|
  c.before(:all) do
    DatabaseCleaner.clean
  end
  c.after(:each) do
    DatabaseCleaner.clean
  end
end

Testing validations

describe "Validations" do
  it "is invalid without a title" do
    film = Film.new(year: 2017, box_office_sales: 2)

    expect(film).to_not be_valid
  end
end

In the Film model

validates :name, presence: true

Practice

• a test for an .average_box_office_sales class method
• tests that a film cannot be created without a year or box_office_sales

Takeaways

• RSpec organizes tests using describe and it blocks
• We run our tests in the test environment so that we don’t have to worry about data in our development database
• DatabaseCleaner can be used to clean your test database
• RSpec and DatabaseCleaner have gems that we can use in our projects
• We can test methods that exist on models as well as validations
• Specific setup steps can be looked up