module ChefSpec::Cacher

The cacher module allows for ultra-fast tests by caching the results of a CCR in memory across an example group. In testing, this can reduce the total testing time by a factor of 10x. This strategy is not the default behavior, because it has implications surrounding stubbing and is not threadsafe!

The credit for this approach and code belongs to Juri Timošin (DracoAter). Please see his original blog post below for an in-depth explanation of how and why this approach is faster.

@example Using the Cacher module

First, require the Cacher module in your +spec_helper.rb+:

  RSpec.configure do |config|
    config.extend(ChefSpec::Cacher)
  end

Next, change your +let+ blocks to +cached+ blocks:

  let(:chef_run) { ... } #=> cached(:chef_run) { ... }

Finally, celebrate!

@warn

This strategy is only recommended for advanced users, as it makes
stubbing slightly more difficult and indirect!

@see dracoater.blogspot.com/2013/12/testing-chef-cookbooks-part-25-speeding.html

Constants

FINALIZER

Public Instance Methods

cached(name, &block) click to toggle source
# File lib/chefspec/cacher.rb, line 36
def cached(name, &block)
  location = ancestors.first.metadata[:location]
  unless location.nil?
    location += ancestors.first.metadata[:description] unless ancestors.first.metadata[:description].nil?
    location += ancestors.first.metadata[:scoped_id] unless ancestors.first.metadata[:scoped_id].nil?
  end
  location ||= ancestors.first.metadata[:parent_example_group][:location]

  define_method(name) do
    key = [location, name.to_s].join(".")
    unless @@cache.key?(Thread.current.object_id)
      ObjectSpace.define_finalizer(Thread.current, FINALIZER)
    end
    @@cache[Thread.current.object_id] ||= {}
    @@cache[Thread.current.object_id][key] ||= instance_eval(&block)
  end
end
cached!(name, &block) click to toggle source
# File lib/chefspec/cacher.rb, line 54
def cached!(name, &block)
  cached(name, &block)

  before { send(name) }
end