Testing Helpers in Padrino

This article is part of an ongoing series about my exploration of the Padrino web framework. If you want to read more about it please check out padrinobook.com. You sniff around in the sources of the book under GitHub.

I always was wondering how to test helpers in Padrino and to be honest I postponed this problem for a long time. But this morning I reached the point in my book where I was writing helper with many methods without testing them. When something like this happened you have stop going and spend time to solve this problem.

The Problem

Let's say you have a typical Padrino helper:

# app/helpers/users_helper.rb

JobVacancy::App.helpers do
  def foo
    "bar"
  end
end

You can use the foo method anywhere in you controllers and views. But what happened if your helper is getting more and more complex like the following one:

# app/helpers/users_helper.rb

JobVacancy::App.helpers do
  def current_user=(user)
    @current_user = user
  end

  def current_user
    @current_user ||= User.find_by_id(session[:current_user])
  end

  def current_user?(user)
    user == current_user
  end

  def sign_in(user)
    session[:current_user] = user.id
    self.current_user = user
  end

  def sign_out
    session.delete(:current_user)
  end

  def signed_in?
    !current_user.nil?
  end
end

Right, there is a lot of stuff inside and you need to test this.

Assumption

Let's say you have the following structure within you application:

.
├── app
│   ├── controllers
│   │   ├── ...
│   ├── helpers
│   │   ├── users_helper.rb
│   │   ├── ...
│   ├── models
│       └── ...
├── spec
│   ├── app
│   │   ├── controllers
│   │   │   ├── ...
│   │   ├── helpers
│   │   │   └── users_helper_spec.rb
│   │   ├── models
│   │   │   └── ...
│   ├── spec_helper.rb

And you have written your helper in the typical helper style of Padrino which are generated when you create a new controller:

# app/helpers/users_helper.rb

JobVacancy::App.helpers do
  def foo
    "bar"
  end
end

This syntax is a shortcut for:

helpers = Module.new do
  def foo
    "bar"
  end
end

JobVacancy::App.helpers helpers

In Padrino, helpers are generally an anonymous module. Testing something anonymous isn't possible. To make this helper testable we need to make this module explicit:

# app/helpers/users_helper.rb

module UsersHelper
  def foo
    "bar"
  end
end

JobVacancy::App.helpers UsersHelper

You can still use the foo method everywhere in your views and controller. But now you've got a big plus. You can test it.

Prepare the Spec

We need to require the helper in our spec_helper:

# spec/spec_helper.rb

PADRINO_ENV = 'test' unless defined?(PADRINO_ENV)
require File.expand_path(File.dirname(__FILE__) + "/../config/boot")
require File.dirname(__FILE__) + "/../app/helpers/users_helper" # <--- this is what we need

RSpec.configure do |conf|
  ...
  conf.full_backtrace= false
  conf.color_enabled= true
  conf.formatter = :documentation
end

Write the spec

And here is a spec for that:

# spec/app/helpers/users_helper_spec.rb
require 'spec_helper'

describe UsersHelper do
  before do
    class UsersHelperClass
      include UsersHelper
    end

    @user_helper = UsersHelperClass.new
  end

  it "test foo" do
    @user_helper.foo.should == "bar"
  end

end

We create a class in the before part of the spec which include our UsersHelper module. Next, we are creating the instance variable @user_helper as a new object of our class UsersHelperClass. Running our tests will make unicorns happy and fast:

$ rspec spec/app/helpers

  UsersHelper
    test foo

  Finished in 0.00041 seconds
  1 example, 0 failures

I'm quiet sure that there is a better way to write the spec. If you know a way, please let me know.