Elasticsearch: Undefined method 'perform' for #<Indexer...> [test env] - ruby-on-rails

Question

I'm writing tests for my app (in Rspec) and lost a whole day trying to figure out where did I make a mistake with Capybara. I noticed that when a action is called (change_status), the following errors occur in the test.log:
undefined method `perform' for #<Indexer:0x000000095d9680>
and the changes are not saving. I have no idea where to start looking. I'm guessing it's a problem with Elasticsearch. Here's the whole action from the controller:
def change_status
product = Product.find_by(id: params[:id])
product.update_attribute(:status, params[:product][:status])
if params[:product][:status] == "accepted"
kind = Kind.where(name: "title").first
product.author.change_points({points: 2, kind: kind.id})
elsif params[:product][:status] == "rejected"
kind = Kind.where(name: "title").first
product.author.change_points({points: 1, kind: kind.id})
product.author.change_points({points: -3, kind: kind.id})
end
user_id = product.author_id
products = Product.where(author_id: user_id)
if products.where(status: "accepted").count == 3
user = User.find_by(id: user_id)
user.update_attribute(:approved, true)
kind = Kind.where(name: "title").first
user.change_points({points: 1, kind: kind.id})
redirect_to products_path
else
redirect_to action: "pending_products", id: user_id
end
end
Any suggestion? Besides this, the log is useless...
EDIT:
class Indexer
include Sidekiq::Worker
sidekiq_options queue: 'elasticsearch', retry: false, backtrace: true
Logger = Sidekiq.logger.level == Logger::DEBUG ? Sidekiq.logger : nil
Client = Elasticsearch::Client.new host: (ENV['ELASTICSEARCH_URL'] || 'http://localhost:9200'), logger: Logger
def perform(operation, klass, record_id, options={})
logger.debug [operation, "#{klass}##{record_id} #{options.inspect}"]
case operation.to_s
when /index|update/
record = klass.constantize.find(record_id)
record.__elasticsearch__.client = Client
record.__elasticsearch__.__send__ "#{operation}_document"
when /delete/
Client.delete index: klass.constantize.index_name, type: klass.constantize.document_type, id: record_id
else raise ArgumentError, "Unknown operation '#{operation}'"
end
end
end