Category: programming

TL;DR; you cannot do it reliably with RSpec.

The long story goes like this. Lets say you have a code executing an AR rollback when something fails:

def call
  Model.transaction do
    update_reason

    unless send_notification
      raise ActiveRecord::Rollback
    end
  end
end

This update_reason is a block of code, which does some database operation, like an INSERT or UPDATE:

def update_reason
  object.update reason: reason
end

And send_notification is just some external API call.

So when you write a spec for this code, you might want to write something like this:

describe '#call' do
  it 'does not update the reason when sending the notification fails' do
    allow(object).to receive(:send_notification).and_return false
    
    expect {
      object.call
    }.not_to change(object, :reason)  
end

And, surprise, surprise, the above spec will fail! The reason will change on the object, even though the logic says it should not.

Why is that? This is because normally you have your whole example spec wrapped in a transaction and rolled back after the example has been run. Since your code opens up a new, nested transaction internally (with the #call method: Model.transaction do). This messes things up and now the rollback in the nested transaction does not really roll back anything. Adding require_new: true doesn’t help. Disabling transaction just for this one spec does not work either. Unfortunately.

Something like this works, but it’s not ideal:

expect {
  object.call
}.to raise_exception ActiveRecord::Rollback 

Additional reading:

* How to test that a certain function uses a transaction in Rails

This guide is valid for i18n version 0.7.0+ and Rails 4.1+

Strangely enough enabling custom locale fallbacks is harder than it should be. Here’s what you need to enable custom locale fallbacks with i18n gem.

First, you need to set config.i18n.fallbacks = true for all environments in a Rails application (config/environments/*.rb).

Then you need to have this in your config/application.rb:

# The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
# config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
config.i18n.default_locale = :en

# Enforce available locales
config.i18n.enforce_available_locales = true

# Custom I18n fallbacks
config.after_initialize do
  I18n.fallbacks = I18n::Locale::Fallbacks.new(at: :"de-DE", ch: :"de-DE", gb: :"en-US")
end

The above will enable custom fallbacks from at and ch locales to the German language and from gb locale to English. The enforce_available_locales bit is optional.

If you also use i18n-js to have your translated phrases available in javascript, here’s the exemplary fallbacks snippet you need to put inside your javascript code:

I18n.locales["at"] = ["de", "en"]
I18n.locales["ch"] = ["de", "en"]
I18n.locales["gb"] = ["en"]

Ever wanted to test your CSRF protection in a Rails app? For example, in a situation when you have a custom “remember me” cookie set and you need to overwrite Rails’ handle_unverified_request to clear it so it does not open a big security hole in your app? I know I did and it took me a while to find out how to do that, so I figured it would be good to write about it.

Here’s how to do it (in Test::Unit, but it’s the same for RSpec):

setup do                                                           
  # Enable CSRF protection in this test                            
  ActionController::Base.allow_forgery_protection = true           
end                                                                
                                                                   
teardown do                                                        
  # Disable CSRF protection for all other tests                    
  ActionController::Base.allow_forgery_protection = false          
end

Adding the above will make it so that the authenticity_token is added to each generated <form> element and will be required to be sent with each non GET request.

If you run into this problem, which by the way usually happens after upgrading the rubygems package (in my case it was to version 1.8.21), your best bet is to upgrade the gem from the backtrace of this error. In my case it was the old passenger version 3.0.9, which was causing this problem. Upgrading to 3.0.11 solved it.

Seems like it’s not so straightforward. Here’s the excerpt from my config/deploy.rb:

require "bundler/capistrano"
set :bundle_dir,     ""         # install into "system" gems
set :bundle_flags,   "--quiet"  # no verbose output
set :bundle_without, []         # bundle all gems (even dev & test)

Maybe someone finds it helpful.

Completely bad code follows, beware.

Silent error in Ruby 1.8.7:

x = [:a, :b]
=> [:a, :b]

x.slice!(:a)
=> nil

x
=> [:a, :b]

Explicit error (resulting in a failing test) in Ruby 1.9.2:

x = [:a, :b]
=> [:a, :b]

x.slice!(:a)
TypeError: can't convert Symbol into Integer

Just yet another incompatibility, but for the better!