Add custom test group to rake test

testing.rake

# Add test:workers rake task, and include it in the normal test run
namespace :test do
  task run: ['test:workers']

  ['workers'].each do |name|
    Rails::TestTask.new(name => 'test:prepare') do |t|
      t.pattern = "test/#{name}/**/*_test.rb"
    end
  end
end