How to test ElasticSearch in a Rails application

Since I started using ElasticSearch in my Rails applications, I had a problem to create separate indexes for the automated tests.

The problem is: there is no way to create more than one database in ElasticSearch. You can create different indexes, but no different databases. But creating indexes with different names doesn’t solve the problem: it’s necessary to configure our Rails models in order to work with a different index name when the tests is running.

I’m using the tire and RSpec gems and in this post, I’ll explain how to separate indexes for development and test environments.

First of all, I’ve included the code below in file config/initializers/tire.rb:

if Rails.env.test?
  prefix = "#{Rails.application.class.parent_name.downcase}_#{Rails.env.to_s.downcase}_"
  Tire::Model::Search.index_prefix(prefix)
end

And I set manually the index name in the model (assuming that there is a Movie model):

index_name "#{Tire::Model::Search.index_prefix}movies"

Done! After that, when your application is running in development environment, the name of indexes will be “movies”. But if it’s in the test environment, the name of indexes will be “appname_test_movies” and then the tire gem and your models can perform the search with different indexes!

Deleting test indexes

In order to delete the test indexes after the suite has finished running, just add the following code to file spec/integration_helper.rb (or similar):

RSpec.configure do |config|
  config.after(:all, type: :request) { delete_movie_index }
end

And create a custom macro, which will delete the indexes:

def delete_movie_index
  Movie.index.delete
end

Demo app

I created a small application to demonstrate the technique explained in this post:
https://github.com/lucascaton/elasticsearch_app_example

I hope this has been helpful!