Testing hardware-specific recipes with chefpsec

One of the complaints I hear about chefspec is that you cannot test hardware-specific recipes with chefspec. Oh, but you can.

Remember, chefsepc is about testing the logic in your recipes. Did the correct resources get created?

Given the following recipe:

require 'chef/sugar'

case node.deep_fetch('dmi', 'system', 'manufacturer')
when 'Dell Inc.'
  package 'raidcfg'

when 'HP'
  package 'hpacucli'
end

You can write chefspec test like:

require 'chefspec'

describe 'raid::utils' do
  context 'on Dell' do
    let :runner do
      ChefSpec::Runner.new do |node|
        node.automatic['dmi']['system']['manufacturer'] = 'Dell Inc.'
      end.converge(described_recipe)
    end

    it 'converges' do
      expect(runner).to install_package('raidcfg')
      expect(runner).not_to install_package('hpacucli')
    end
  end

  context 'on HP' do
    let :runner do
      ChefSpec::Runner.new do |node|
        node.automatic['dmi']['system']['manufacturer'] = 'HP'
      end.converge(described_recipe)
    end

    it 'converges' do
      expect(runner).not_to install_package('raidcfg')
      expect(runner).to install_package('hpacucli')
    end
  end
end

This works but it is a rather short sided approach. What happens in six months when you need to support another hardware vendor? You would need to go back and update all the spec tests in all of the cookbooks.

A better way of doing this using real data. I have a gem CSH (Chef Spec Helpers) that contains ohai data from all of the hardware platforms in our data centers.

$ ls -1 hardware
ESX_Guest.json
Intel_D945GCLF2.json
OpenStack_Guest.json
PowerEdge_M620.json
PowerEdge_M710HD.json
PowerEdge_R310.json
PowerEdge_R320.json
PowerEdge_R410.json
PowerEdge_R420.json
PowerEdge_R510.json
PowerEdge_R720.json
PowerEdge_R720xd.json
ProLiant_DL360e_Gen8.json
ProLiant_DL360p_Gen8.json
ProLiant_DL380p_Gen8.json
VirtualBox_Guest.json
Xen_Guest.json

The excerpt from CSH:

# encoding: UTF-8

module CSH
  HARDWARE = {
    dell: %w[
      PowerEdge_M620
      PowerEdge_M710HD
      PowerEdge_R310
      PowerEdge_R320
      PowerEdge_R410
      PowerEdge_R420
      PowerEdge_R510
      PowerEdge_R720
      PowerEdge_R720xd
    ],
    hp: %w[
      ProLiant_DL360e_Gen8
      ProLiant_DL360p_Gen8
      ProLiant_DL380p_Gen8
    ],
    other: %w[
      Intel_D945GCLF2
    ],
    virtual: %w[
      ESX_Guest
      OpenStack_Guest
      VirtualBox_Guest
      Xen_Guest
    ]
  }

  # iterate over specified platforms
  def self.each_hardware(*kinds, &block)
    array = []
    kinds = HARDWARE.keys if kinds.empty?
    kinds.each do |k|
      fail "Unknown kind #{k.inspect}" unless HARDWARE.include?(k)
      array.concat HARDWARE[k]
    end
    array.each do |desc|
      file = File.join(File.dirname(__FILE__), 'hardware', "#{desc}.json")
      ohai = JSON.parse(IO.read(file))
      yield desc, ohai
    end
  end
end

The chefspec tests then become:

require 'chefspec'
require 'csh'

describe 'raid::utils' do
  CSH.each_hardware do |machine, json|
    context "on #{machine}" do
      let :runner do
        ChefSpec::Runner.new do |node|
          node.automatic.merge! json['automatic']
        end.converge(described_recipe)
      end

      it 'converges' do
        if machine =~ /^PowerEdge/
          expect(runner).to install_package('raidcfg')
        else
          expect(runner).not_to install_package('raidcfg')
        end

        if machine =~ /^ProLiant/
          expect(runner).to install_package('hpacucli')
        else
          expect(runner).not_to install_package('hpacucli')
        end
      end
    end
  end
end

This while iterate over all hardware platforms and run the tests. Now if another hardware platform to the mix, I can just update CSH. Rarely do I have to update the spec tests themselves.

CSH.each_hardware provides a lot of flexibility for test writing. Say I have a recipe:

return if node['virtualization']['role'] == 'guest'

package 'foo'
package 'bar'

Corresponding tests would be:

describe 'dummy::test' do
  CSH.each_hardware do |machine, json|
    context "on #{machine}" do
      let :runner do
        ChefSpec::Runner.new do |node|
          node.automatic.merge! json['automatic']
        end.converge(described_recipe)
      end

      it 'converges' do
        if machine =~ /_Guest$/
          expect(runner.resource_collection).to be_empty
        else
          expect(runner).to install_package('foo')
          expect(runner).to install_package('bar')
        end
      end
    end
  end
end

When you know a recipe is a no-op, I prefer expect(runner.resource_collection).to be_empty over a bunch of expect(runner).not_to clauses.