The email_preview gem has undergone a serious overhaul in the last week. After some extensive real-world project use, a new version has been released with some major improvements.

Transactional Fixtures

At a high level, email_preview fixtures are very similar in nature to Rails test fixtures. They are a snapshot of data with a particular configuration and are not intended to be long lived outside of the email_preview. The setup and teardown of previewed emails should follow the same setup/teardown of fixture data used during unit testing. Now each email_preview action is wrapped in a database transaction and rolled back after completion to avoid polluting your sandbox with unnecessary data!

# config/initializers/email_preview.rb
EmailPreview.register 'User activation email' do
  u = User.create :email => 'foo@example.com'
  UserMailer.activation(u)
end

Factories

Why duplicate the setup of fixture data when building your email preview templates? You already use a factory library for your unit tests right? The email_preview gem now works great with any factory framework you choose (FactoryGirl, Machinist, etc).

# config/initializers/email_preview.rb
# example FactoryGirl fixture
EmailPreview.register 'User activation email' do
  u = Factory.create :user
  UserMailer.activation u
end

Categories

Email is still a critical component of most web applications, and it’s very easy to rack up lots of templates when working with a large application. To help organize your fixtures, you can now use an optional :category option to group related fixtures.

# config/initializers/email_preview.rb
EmailPreview.register 'User activation email', :category => :user do
  u = User.new :email => 'foo@example.com'
  UserMailer.activation(u)
end

The email_preview UI received a considerable overhaul as well and any suggestions are greatly welcome. A solid update all around, and special thanks go to Lars Klevan for inspiring several of these updates!