I think that many of you think writing tests for custom Rake tasks is redundant. But as practice shows, if you think so, you are wrong. In this post I will show how to test custom rake tasks.

Issue

Assume that we have a Rake task, for example products:load, and you can run it from the terminal with the following command: rake products:load. At first glance, you could test it manually when running spec, or you could configure the default Rake task to run RSpec and this task. But the 1st approach has a side effect: your Rake task will always populate the database with products. We don’t want to do that; we just want to make sure that the task works. The 2nd approach looks more robust, but if you use the default Rake task for other things, it’s definitely not your choice. I prefer to test Rake tasks with RSpec.

Solution

Check out rspec test below:

require 'spec_helper'
require 'rake'

describe 'db:seeds' do
  before { MyApp::Application.load_tasks }

  it { expect { Rake::Task['products:load'].invoke }.not_to raise_exception }
end

MyApp::Application is my application name; you can get it from config/application.rb:

module MyApp
  class Application < Rails::Application
    ...
  end
end

I hope this code doesn’t require a deeper explanation and the other lines are clear to you.