3.times do
  begin
    raise "Nope"
  rescue
    puts "Failed"
  else
    puts "Success"
    break
  end
end

Usage

class Waldo < MissingType
end

Code

class MissingType < ActiveRecord::Base
  default_scope :conditions => "1 = 2", :limit => 0

  self.table_name = "schema_migrations"

  def self.primary_key
    "version"
  end

  def readonly?
    true
  end
end

curl https://raw.github.com/mitchellh/vagrant/master/keys/vagrant > vagrant.key
chmod 600 vagrant.key
knife solo cook --ssh-identity vagrant.key vagrant@vagrant

Usage

RawSidekiq.enqueue("XyzJob", [1,2,3], :namespace => "custom")

Code

# http://grosser.it/2013/01/17/enqueue-into-sidekiq-via-pure-redis-without-loading-sidekiq
require "json"
require "redis"
require "securerandom"

class RawSidekiq
  def self.enqueue(queue, klass, args, options={})
    payload = {
      'class' => klass,
      'args' => args,
      'jid' => SecureRandom.hex(12),
      #'retry' => true
    }.to_json

    conn = Redis.new
    conn.multi do
      conn.sadd([options[:namespace], "queues"].compact.join(":"), queue)
      conn.lpush([options[:namespace], "queue", queue].compact.join(":"), payload)
    end
  end
end

• decreases startup time by not loading all your models
• makes it possible to preload config/environment.rb and still test models -> spin/zeus
• makes dependencies obvious
• replaces ActiveRecord magic with ruby
• makes your app Rails 4 ready

Before:

# config/environment.rb
config.observers = [:foo_observer] 

# app/observers/foo_observer.rb
class FooObserver < ActiveRecord::Observer
  observes :user

  def after_save(user)
    ....
  end
end

After:

# app/models/user.rb
class User < ActiveRecord::Base
  include FooObserver
end

# app/observers/foo_observer.rb
module FooObserver
  class << self
    def included(base)
      this = self
      base.after_save{|user| this.more_descriptive_name(user) }
    end

    def more_descriptive_name(user)
      ...
    end
  end
end

# http://grosser.it/2012/10/19/upgrading-to-rails-3-0-making-sure-you-use-rack-headers-everywhere/
# message can be changed on rails 3, but keep the warning, it's so hard to track down missing headers
# maybe try to remove in rails 3.1+
# can be tested by e.g. changing header to Accept instead of HTTP_ACCEPT
class ActionController::Integration::Session
  # headers that are only used by our code and not rails/rack can be whitelisted, but make sure they work on rails 2 and 3
  HEADER_WHITELIST = ['Funky-Headers-You-Have-To-Use']
  def process_with_header_warning(*args)
    if args[3] && bad = args[3].keys.detect{|k| !k.is_a?(String) || (!HEADER_WHITELIST.include?(k) && k !~ /^[A-Z_\d]+$/) }
      raise "Header #{bad} will not work on rails 3, please uppercase (Content-Type -> CONTENT_TYPE) and prefix HTTP_ (Accept -> HTTP_ACCEPT)"
    end
    process_without_header_warning(*args)
  end
  alias_method_chain :process, :header_warning
end

See actionpack-2.3.14/lib/action_controller/integration.rb:342

To fix that and prepare for Rails 3 (which also relies on rack response) do this:

# test/test_helper.rb

if Rails::VERSION::MAJOR == 2
  # http://grosser.it/2012/10/19/rails-2-your-integration-tests-are-lying/
  # make integration tests use rack response, so we can test our middlewares
  # and not only the pure controller response

  ActionController::Base.class_eval do
    # this is usually done just-in-time by #process but we need to do it earlier
    include ActionController::Integration::ControllerCapture

    # then we hide last_instantiation from #process
    def self.last_instantiation;end
  end

  ActionController::Integration::Session.class_eval do
    def process_with_rackify(*args)
      process_without_rackify(*args)
    ensure
      # needed e.g. inside of assert_redirect_to
      capture = ActionController::Integration::ControllerCapture::ClassMethods

      # not set by original #process
      @response.redirected_to = @response.headers["Location"] if @response
      if @controller = capture.send(:class_variable_get, :@@last_instantiation)
        @request = @controller.request
        @response.template = @controller.response.template if @controller.response
        @controller.send(:set_test_assigns)
      end
    end
    alias_method_chain :process, :rackify
  end
end

# application_controller_test.rb
class ApplicationControllerTest < ActionController::TestCase
  class CleanController < ApplicationController
  end

  test "should be clean" do
    assert_equal [], CleanController.action_methods.to_a.
      reject{|a| a =~ /^_conditional_callback_around_/}
  end
end

Usage
Use auth-token from settings page, not your api-key.

ruby airbrake_backtraces.rb your-account your-auth-token error-id

Output

Trace 1: occurred 597 times
...funky backtraces...
Trace 2: occurred 119 times
...funky backtraces...
Trace 3: occurred 13 times
...funky backtraces...

Code

#! /usr/bin/env ruby
# lists all sources of a given error
# http://grosser.it/2012/09/08/airbrake-error-summary
#
# gem install airbrake-api
# USAGE: ruby airbrake_backtraces.rb your-account your-auth-token error-id
# https://your-account.airbrake.io/errors/ID

require "airbrake-api"

AirbrakeAPI.account = ARGV[0] || raise("need airbrake account as ARGV[0]")
AirbrakeAPI.auth_token = ARGV[1] || raise("need airbrake token as ARGV[1], go to airbrake -> settings, copy your auth token")
AirbrakeAPI.secure = true

error_id = ARGV[2] || raise("need error id")
compare_depth = (ARGV[3] || 4).to_i

notices = AirbrakeAPI.notices(error_id, :pages => 20)
backtraces = notices.select{|n| n.backtrace }.group_by do |notice|
  notice.backtrace.first[1][0..compare_depth]
end

backtraces.sort_by{|k,t| t.size }.reverse.each_with_index do |(key, traces), index|
  puts "Trace #{index + 1}: occurred #{traces.size} times"
  puts key
  puts ""
end

Usage
auth_token can be found on your settings page, it is NOT the api-key.

ruby airbrake_search.rb your-account your-auth-token | grep foo

Code

#! /usr/bin/env ruby
# http://grosser.it/2012/09/08/airbrake-search
# search for errors given a name
#
# gem install airbrake-api
# USAGE: ruby airbrake_search.rb your-account your-auth-token | grep SOMETHING
# https://your-account.airbrake.io/errors/ID

require "airbrake-api"

AirbrakeAPI.account = ARGV[0] || raise("need airbrake account as ARGV[0]")
AirbrakeAPI.auth_token = ARGV[1] || raise("need airbrake token as ARGV[1], go to airbrake -> settings, copy your auth token")
AirbrakeAPI.secure = true

page = 1
while errors = AirbrakeAPI.errors(:page => page)
  errors.each do |error|
    puts "#{error.id} -- #{error.error_class} -- #{error.error_message} -- #{error.created_at}"
  end
  $stderr.puts "Page #{page} ----------\n"
  page += 1
end