(maint) Switch from is_function_available() to defined()

stdlib 9 dropped the is_function_available() function. I reworked the
code to check if `pe_anchor` is defined. The code now works with Puppet
core functions and is compatible with Puppet 7/8, probably 6, and does
not rely on stdlib.

Author: bastelfreak

manifests/params.pp

@@ -43,8 +43,9 @@
   # The `is_pe` fact currently works by echoing out the puppet version
   # and greping for "puppet enterprise". With Puppet 4 and PE 2015.2, there
   # is no longer a "PE Puppet", and so that fact will no longer work.
-  # Instead check for the `is_pe` fact or if a PE provided function is available
-  $_is_pe = (getvar('::is_pe') or is_function_available('pe_compiling_server_version'))
+  # Instead check for the `is_pe` fact or if the `pe_anchor` resource type
+  # provided by the puppet_enterprise module exist.
+  $_is_pe = (getvar('::is_pe') or defined('pe_anchor'))
   if $_is_pe {
     # Calculate the default collection
     $_pe_version = pe_build_version()

spec/classes/puppet_agent_spec.rb

@@ -237,7 +237,7 @@ def global_facts(facts, os)
         before(:each) do
           Puppet::Parser::Functions.newfunction(:pe_build_version, type: :rvalue) { |_args| '2000.0.0' }
           Puppet::Parser::Functions.newfunction(:pe_compiling_server_aio_build, type: :rvalue) { |_args| '1.10.100' }
-          Puppet::Parser::Functions.newfunction(:pe_compiling_server_version, type: :rvalue) { |_args| '2.20.200' }
+          Puppet::Parser::Functions.newfunction(:defined, type: :rvalue) { |_args| true }
         end
 
         context 'package_version is initialized automatically' do