rspec-with-rails.md

Rspec with Rails

In this lesson we will learn:

• Creating a Rails app without test unit.
• Setting up rspec with Rails
• Testing models
• Testing controllers

Rails new

First we will create a new rails app to implement rspec into. But, since we'll be using rspec, I want to leave out Test::Unit so it doesn't clutter up my app.

rails new twitter_ripoff -T -d postgresql

The -T is the flag to leave out Test::Unit

Rspec setup

Next we'll add the rspec gem to our application. In the Gemfile

group :development, :test do
  gem 'rspec-rails'
end

Install the gems within our Gemfile

bundle install

Now that the rspec-rails gem is installed we can run the one-time rspec installer for our project

rails generate rspec:install

This command creates the necessary directories and files to run our specs. The most notable is spec/spec_helper.rb, this file is where all of our testing setup is done. The rpsec install command added pretty much everything we need to the file.

Now rspec is ready, let's create some code to test.

Testing models

First create a model.

rails g model post body:text user_id:integer

We can see this command created three things:

invoke  active_record
create  db/migrate/20131209161227_create_posts.rb
create  app/models/post.rb
invoke  rspec
create  spec/models/post_spec.rb

First a migration to setup our database, next the class our logic will go in post.rb, and finally a post_spec.rb file which is where we will write tests for this model. Let's run our migrations

rake db:migrate

In the spec/models/post_spec.rb we can see that some of the structure for writing rspec tests already exists. We have a pending spec, this syntax can be useful for keeping track of upcoming tasks. But we don't need it, so replace that line with a new test:

describe ".validates" do
  it "must have a body" do
    expect(Post.new(body: nil)).to_not be_valid
  end
end

We have our first spec, let's run it.

rspec

We get a failure (that's good), let's fix it in app/models/post.rb:

class Post < ActiveRecord::Base
  validates :body, presence: true
end

Then run it again

rspec

It passes, and let's add a few more tests to spec/models/post_spec.rb

describe ".validates" do
  it "must have a body" do
    expect(Post.new(body: nil)).to_not be_valid
  end

  it "can't have 141 char body" do
    expect(Post.new(body: "a" * 141)).to be_invalid
  end

  it "can have 140 char body" do
    expect(Post.new(body: "a" * 140)).to be_valid
  end
end

it "counts it's characters" do
  expect(Post.new(body: "a" * 122).character_count).to eq 122
end

Run rspec, you should have 2 failing tests. Let's fix them in post.rb:

validates :body, presence: true, length: { maximum: 140 }

def character_count
  body.length
end

Run rspec, and now they pass!

Controller specs

Open a new tab in Terminal (Command T), and create a controller:

rails g controller posts

This command creates quite a few files, the ones we are going to focus on are the actual controller and it's associated spec file:

app/controllers/posts_controller.rb
spec/controllers/posts_controller_spec.rb

Let's open spec/controllers/posts_controller_spec.rb and write a controller spec.

describe PostsController do
  describe "GET 'index'" do

    it "is successful" do
      get :index
      expect(response.status).to eq 200
    end

  end
end

run rspec

Failure/Error: get :index
  ActionController::UrlGenerationError:
    No route matches {:action=>"index", :controller=>"posts"}

No route matches tells me this is a problem with our routes.rb file. Lets add the needed code:

get "/posts" => "posts#index"

Since our routes file is not part of the PostsController, we may need to manually run our specs to see the result, we can do that be going to the Guard tab in Terminal and just hitting the return key. Now the error we get is:

Failure/Error: get :index
  AbstractController::ActionNotFound:
    The action 'index' could not be found for PostsController

Next create an index action in our PostsController

class PostsController < ApplicationController
  def index
  end
end

Next our error is Missing template posts/index, let's create the template (or view).

touch app/views/posts/index.html.erb

It passes!

Let's look at the syntax of our controller spec.

get :index
# => This attempts to make an HTTP request with the method `get` to the `index` action

expect(response.status).to eq 200
# => response is typically the object we want to test in controller specs

Rails specs have a lot of extra syntax from regular rspec. See the rspec cheat sheet to learn about more the matchers.