Testing

Postman is helpful to help us test our endpoints. But, what if we have 10 endpoints? Are we really going to manually click on Postman for each one of the 10 endpoints every time we modify our code?

Postman becomes unscalable when we have 10, 50, 100 endpoints. So, instead of manual testing, we write code for automated testing. You heard it right! We are writing software to test other softwares.

Generally, we call these softwares tests or specs (specifications). Remember we have actually done this in Ruby Koans? We write code to pass tests. Here, it's the same concept. We are writing tests to test the entire MVC framework.

Rspec

We are going to use the Rspec gem for testing in Rails.

Add rspec-rails to both the :development and :test groups in the Gemfile:

...

group :development, :test do
  gem 'rspec-rails', '~> 3.5'

  ...
end

...

Install new gems by running $ bundle install.

Initialize the spec/ directory (where specs will reside) with: $ rails generate rspec:install. As you can guess, Rspec calls tests specs, hence the specs folder.

$ rails generate rspec:install

      create  .rspec
      create  spec
      create  spec/spec_helper.rb
      create  spec/rails_helper.rb

Great! Now, let's run the specs with $ rspec

$ rspec

No examples found.

Finished in 0.00039 seconds (files took 0.35769 seconds to load)
0 examples, 0 failures

As expected, we haven't written any specs yet, so there are no examples and no failures.

Rspec can be used to test the entire MVC framework, including but not limited to:

1. Model Specs
2. Controller Specs
3. Helper Specs
4. Integration Specs

Again, we have a way to generate these specs files. To generate a controller spec, run:

$ rails g rspec:controller books

      create  spec/controllers/books_controller_spec.rb

The format here is rails g rspec:<type of spec> <name of spec>.

In spec/controllers/books_controller_spec.rb,

require 'rails_helper'

RSpec.describe BooksController, type: :controller do

end

So now, let's replicate what we had in Postman to test the POST /books endpoint.

We will attempt to translate the following:

Into Rspec:

RSpec.describe BooksController, type: :controller do
  describe 'POST /books' do
    it 'create a new book object' do
      post :create, params: { name: 'Harry Potter' }

      expect(Book.count).to eq(1)
    end
  end
end

post :create, params: { name: 'Harry Potter' } creates a POST request to the method create in the BooksController. It passes parameters as a hash { name: 'Harry Potter' }.

expect(Book.count).to eq(1) means that we expect Book.count to equal to 1.

$ rspec
.

Finished in 0.04074 seconds (files took 3.17 seconds to load)
1 example, 0 failures

And, our first test has passed!