---
title: "Properly testing Rails 3 scopes"
kind: article
slug: properly-testing-rails-3-scopes
created_at: 2011-09-25
tags:
  - Ruby on Rails
  - Rails
  - rspec
  - rails3
  - scope
  - named_scope
---
<p class="important">The content of this post is no longer correct. Please read <a href="http://ariejan.net/2011/10/09/testing-rails-3-scopes-revisited">this article</a> for details.</p>

Testing scopes has always felt a bit weird to me. Normally I'd do something like this:

    :::ruby
    class Post < ActiveRecord::Base
      scope :published, where(:published => true)
      scope :latest, order("created_at DESC")
    end

    describe Post do
      context 'scopes' do
        before(:all) do
          @first = FactoryGirl.create(:post, :created_at => 1.day.ago, :published => true)
          @last  = FactoryGirl.create(:post, :created_at => 4.day.ago, :published => false)
        end

        it "should only return published posts" do
          Post.published.should == [@first]
        end

        it "should return posts in the correct order" do
          Post.latest.should == [@first, @last]
        end
      end
    end

This test is okay. It tests if the named scope does what it needs to do. And there's also the problem. Scopes are part of ActiveRecord and are already extensively tested there. All we need to do is check if we _configure_ the scope correctly.

What we need is a way to inspect what `where` and `order` rules are set for a particular scope and make sure those are the correct ones. We can then trust ActiveRecord to keep its promise to execute the proper SQL query for us.

Here's another test that utilizes some Rails 3 methods you may not have heard of before.

    :::ruby
    describe Post do
      context 'scopes' do
        it "should only return published posts" do
          Post.published.where_values_hash.should == {:published => true}
        end

        it "should return posts in the correct order" do
          Post.latest.order_values.should == ["created_at DESC"]
        end
      end
    end

The `where_values_hash` and `order_values` allow you to inspect what a scopes doing. By writing your test this way you achieve two import goals:

 1. You test _your_ code (instead of the ActiveRecord)
 2. You don't use the database, which is a significant speed boost

Happy testing to you all!