chef

https://github.com/opscode/chef

Ruby

A systems integration framework, built to bring the benefits of configuration management to your entire infrastructure.

Chef::Mixin::WhyRun::ResourceRequirements::Assertion#assertion

Defines the code block that determines if a requirement is met. The
block should return a truthy value to indicate that the requirement
is met, and a falsey value if the requirement is not met.
  # in a provider:
  assert(:some_action) do |a|
    # This provider requires the file /tmp/foo to exist:
    a.assertion { ::File.exist?("/tmp/foo") }
  end

Source | Google | Stack overflow

Edit

git clone [email protected]:opscode/chef.git

cd chef

open lib/chef/mixin/why_run.rb

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-Chef--Mixin--WhyRun--ResourceRequirements--Assertion-assertion-for-pr

# Commit to git

git add lib/chef/mixin/why_run.rbgit commit -m "better docs for Chef::Mixin::WhyRun::ResourceRequirements::Assertion#assertion"

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-Chef--Mixin--WhyRun--ResourceRequirements--Assertion-assertion-for-pr

hub pull-request

# Celebrate!