serverspec で debian パッケージが最新になっているかどうかのテスト。apt-get update を済ませている前提。 https://twitter.com/minimum2scp/status/1032832037625847808

sample_spec.rb

require 'spec_helper'

%w[
  base-files
  openssl
  openssh-server
].each do |pkg|
  describe command("LANG=C apt-cache policy #{pkg}") do
    its(:stdout) {
      should match /\A#{Regexp.quote(pkg)}:\n  Installed: (\S+)\n  Candidate: \1\n/
    }
=begin
    its(:stdout){
      should match(
        /\A#{Regexp.quote(pkg)}:\n  Installed: (?<installed_version>\S+)\n  Candidate: (?<candidate_version>\S+)\n/
      ).with_captures(
        a_hash_including(
          installed_version: be_truthy,
          candidate_version: be_truthy
        ).and(satisfy{|m|
          m[:installed_version] == m[:candidate_version]
        })
      )
    }
=end
  end
end