test(inspec): share library to access some minion informations

The `system.hostname` return the result of either `hostname -s` or
`hostnamectl --static` depending of the availability of each command.

The `system.platform` return a hash with tweaked `inspec.platform`
values:

- `system.platform[:family]` provides a family name for Arch
- `system.platform[:name]` modify `amazon` to `amazonlinux`
- `system.platform[:release]` tweak for Arch and Amazon Linux:
  - `Arch` is always `base-later`
  - `Amazon Linux` release `2018` became `1`
- `system.platform[:finger]` is just the concatenation of the name and
  the first release number (except for Ubuntu which gives `20.04` for
  example)

test/integration/share/README.md

+# InSpec Profile: `share`
+
+This shows the implementation of the `share` InSpec [profile](https://github.com/inspec/inspec/blob/master/docs/profiles.md).
+
+It's goal is to share the libraries between all profiles.
+
+## Libraries
+
+### `system`
+
+The `system` library provides easy access to system dependents informations:
+
+- `system.hostname`: return the result of `hostname -s` or `hostnamectl --static` based on the availability of each commans
+- `system.platform`: take `inspec.platform` and mangle things a bit to be useful
+  - `system.platform[:family]` provides a family name for Arch
+  - `system.platform[:name]` modify `amazon` to `amazonlinux`
+  - `system.platform[:release]` tweak for Arch and Amazon Linux:
+    - `Arch` is always `base-later`
+    - `Amazon Linux` release `2018` became `1`
+  - `system.platform[:finger]` is just the concatenation of the name and the first release number (except for Ubuntu which gives `20.04` for example)

test/integration/share/inspec.yml

+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+name: share
+title: Inspec shared resources
+maintainer: SaltStack Formulas
+license: Apache-2.0
+summary: shared resources
+supports:
+  - platform-name: debian
+  - platform-name: ubuntu
+  - platform-name: centos
+  - platform-name: fedora
+  - platform-name: opensuse
+  - platform-name: suse
+  - platform-name: freebsd
+  - platform-name: amazon
+  - platform-name: arch

test/integration/share/libraries/system.rb

+# frozen_string_literal: true
+
+# system.rb -- InSpec resources for system values
+# Author: Daniel Dehennin <daniel.dehennin@ac-dijon.fr>
+# Copyright (C) 2020 Daniel Dehennin <daniel.dehennin@ac-dijon.fr>
+
+HOSTNAME_CMDS = %w[hostname hostnamectl].freeze
+HOSTNAME_CMDS_OPT = {
+  'hostname' => '-s',
+  'hostnamectl' => '--static'
+}.freeze
+
+class SystemResource < Inspec.resource(1)
+  name 'system'
+
+  attr_reader :platform
+  attr_reader :hostname
+
+  def initialize
+    @platform = build_platform
+    @hostname = found_hostname
+  end
+
+  private
+
+  def found_hostname
+    cmd = guess_hostname_cmd
+
+    unless cmd.exit_status.zero?
+      raise Inspec::Exceptions::ResourceSkipped,
+            "Error running '#{cmd}': #{cmd.stderr}"
+    end
+
+    cmd.stdout.chomp
+  end
+
+  def guess_hostname_cmd
+    HOSTNAME_CMDS.each do |cmd|
+      if inspec.command(cmd).exist?
+        return inspec.command("#{cmd} #{HOSTNAME_CMDS_OPT[cmd]}")
+      end
+    end
+
+    raise Inspec::Exceptions::ResourceSkipped,
+          "Error: #{@platform[:finger]}} has none of #{HOSTNAME_CMDS.join(', ')}"
+  end
+
+  def build_platform
+    {
+      family: build_platform_family,
+      name: build_platform_name,
+      release: build_platform_release,
+      finger: build_platform_finger
+    }
+  end
+
+  def build_platform_family
+    case inspec.platform[:name]
+    when 'arch'
+      'arch'
+    else
+      inspec.platform[:family]
+    end
+  end
+
+  def build_platform_name
+    case inspec.platform[:name]
+    when 'amazon'
+      'amazonlinux'
+    else
+      inspec.platform[:name]
+    end
+  end
+
+  def build_platform_release
+    case inspec.platform[:name]
+    when 'amazon'
+      # `2018` relase is named `1` in kitchen.yaml
+      inspec.platform[:release].gsub(/2018.*/, '1')
+    when 'arch'
+      'base-latest'
+    else
+      inspec.platform[:release]
+    end
+  end
+
+  def build_platform_finger
+    "#{build_platform_name}-#{build_finger_release}"
+  end
+
+  def build_finger_release
+    case inspec.platform[:name]
+    when 'ubuntu'
+      build_platform_release.split('.').slice(0, 2).join('.')
+    else
+      build_platform_release.split('.')[0]
+    end
+  end
+end