Puppet implementation patterns: Test with External Function

description.md

Test with External Function

When

You want to test a resource definition (class, defined type) that uses a function provided by a third-party module your module depends upon. It's supposed that you're implementing your tests with rspec-puppet.

How

Add the folder spec/fixtures/<third-party module>/lib to Ruby's $LOAD_PATH.

Notes

According to Brice Figureau (@masterzen):

The Puppet::Parser::Functions class in Puppet core has the task of loading all functions defined in any puppet/parser/functions directories it will be able to find in the whole ruby load path.

Relying on rspec-puppet telling Puppet where to look for modules seems not to be enough to also have functions at disposal. In fact, exercising code that uses a third-party function without the additional step described in this pattern results in a Puppet::Error: Unknown function exception.

example_spec.rb

require 'spec_helper'

describe 'test' do
  let(:title) { 'test integer' }
  let(:params) {{ :integer => 'clearly not an integer' }}

  it 'fails if parameter is not an integer' do
    expect { should raise_error(Puppet::Error, /not an integer/) }
  end
end

spec_helper.rb

require 'rspec-puppet'

# This will make stdlib functions available when test examples will run
$:.unshift File.join(File.dirname(__FILE__),  'fixtures', 'modules', 'stdlib', 'lib')

fixture_path = File.expand_path(File.join(__FILE__, '..', 'fixtures'))

RSpec.configure do |c| 
  c.module_path = File.join(fixture_path, 'modules')
  c.manifest_dir = File.join(fixture_path, 'manifests')
end

test.pp

class test (
  $integer
) {
  # The is_integer function comes from puppetlabs-stdlib module
  if !is_integer($integer) {
    fail "not an integer"
  }
}