Why is my rake task running twice in my test?

Question

I have a rake task test that I setup following the only examples I could find online.

It looks like this:

require 'test_helper'
require 'minitest/mock'
require 'rake'

class TestScrapeWelcome < ActiveSupport::TestCase
  def setup
    Rake.application.init
    Rake.application.load_rakefile

    @task = Rake::Task['scrape:scrape']
    @task.reenable
  end

  def teardown
    Rake::Task.clear
  end

  test "scraping text and sending to elasticsearch" do
    mocked_client = Minitest::Mock.new
    get_fixtures.each_with_index do |arg,i|
      mocked_client.expect :index, :return_value, [index: "test", type: 'welcome', id: i, body: arg]
    end
    Elasticsearch::Model.stub :client, mocked_client do
      @task.invoke
    end
    assert mocked_client.verify
  end

  private

  def get_fixtures
    (0..11).map { |i|
      File.read("test/fixtures/scrape/index_#{i}.json")
    }
  end

end

But after the task runs once it starts running again without me doing anything ( puts prints before and after @task.invoke show that the task is only run the once).

Answer 1

Turns out that rake is already required and initialized when the test runs so all of the following lines need to be removed or the task gets defined twice and runs twice even if you only invoke it once.

require 'minitest/mock'
require 'rake'
...
Rake.application.init
Rake.application.load_rakefile

Answer 2

Updated answer for rails 5.1 (using minitest):

I found I needed the following to load tasks once and only once:

MyAppName::Application.load_tasks if Rake::Task.tasks.empty?

Alternatively add MyAppName::Application.load_tasks to your test_helper, if you don't mind tasks being loaded even when running individual tests that don't need them.

(Replace MyAppName with your application name)

Answer 3

A solution that works for testing the tasks of a Gem that has been made a Railtie so it can add tasks to the Rails app:

Don't define the Railtie in test mode when you're also defining a Rails::Application class in spec_helper.rb (which allows your tests to call Rails.application.load_tasks ). Otherwise the Rake file will be loaded once as a Railtie and once as an Engine:

class Railtie < Rails::Railtie
  rake_tasks do
    load 'tasks/mygem.rake'
  end
end unless Rails.env.test? # Without this condition tasks under test are run twice

Another solution would be to put a condition in the Rake file to skip the task definitions if the file has already been loaded.