Rewrite validate_domain_name() as a Puppet 4.x function

The 3.x function rely on is_domain_name() which is deprecated. Rewrite
it using the more modern puppet 4.x function to rely on data types for
better parameters validation.

While here, adjust the Stdlib::Fqdn data type to ensure the last
component (TLD) is non-numeric as [suggested by @ekohl](#1282 (comment)),
and add a Stdlib::Dns_zone data type that is basically the same but with
a trailing dot.

lib/puppet/functions/validate_domain_name.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# @summary
+#   Validate that all values passed are syntactically correct domain names.
+#   Fail compilation if any value fails this check.
+Puppet::Functions.create_function(:validate_domain_name) do
+  # @param values A domain name or an array of domain names to check
+  #
+  # @return
+  #   passes when the given values are syntactically correct domain names or raise an error when they are not and fails compilation
+  #
+  # @example Passing examples
+  #   $my_domain_name = 'server.domain.tld'
+  #   validate_domain_name($my_domain_name)
+  #   validate_domain_name('domain.tld', 'puppet.com', $my_domain_name)
+  #
+  # @exapmle Failing examples (causing compilation to abort)
+  #   validate_domain_name(1)
+  #   validate_domain_name(true)
+  #   validate_domain_name('invalid domain')
+  #   validate_domain_name('-foo.example.com')
+  #   validate_domain_name('www.example.2com')
+  dispatch :validate_domain_name do
+    repeated_param 'Variant[Stdlib::Fqdn, Stdlib::Dns_zone]', :values
+  end
+
+  def validate_domain_name(*_values); end
+end

spec/functions/validate_domain_name_spec.rb

@@ -5,7 +5,6 @@
 describe 'validate_domain_name' do
   describe 'signature validation' do
     it { is_expected.not_to eq(nil) }
-    it { is_expected.to run.with_params.and_raise_error(Puppet::ParseError, %r{wrong number of arguments}i) }
   end
 
   describe 'valid inputs' do
@@ -18,20 +17,20 @@
   end
 
   describe 'invalid inputs' do
-    it { is_expected.to run.with_params([]).and_raise_error(Puppet::ParseError, %r{is not a string}) }
-    it { is_expected.to run.with_params({}).and_raise_error(Puppet::ParseError, %r{is not a string}) }
-    it { is_expected.to run.with_params(1).and_raise_error(Puppet::ParseError, %r{is not a string}) }
-    it { is_expected.to run.with_params(true).and_raise_error(Puppet::ParseError, %r{is not a string}) }
+    it { is_expected.to run.with_params([]).and_raise_error(ArgumentError, %r{got Array}) }
+    it { is_expected.to run.with_params({}).and_raise_error(ArgumentError, %r{got Hash}) }
+    it { is_expected.to run.with_params(1).and_raise_error(ArgumentError, %r{got Integer}) }
+    it { is_expected.to run.with_params(true).and_raise_error(ArgumentError, %r{got Boolean}) }
 
-    it { is_expected.to run.with_params('foo.example.com', []).and_raise_error(Puppet::ParseError, %r{is not a string}) }
-    it { is_expected.to run.with_params('foo.example.com', {}).and_raise_error(Puppet::ParseError, %r{is not a string}) }
-    it { is_expected.to run.with_params('foo.example.com', 1).and_raise_error(Puppet::ParseError, %r{is not a string}) }
-    it { is_expected.to run.with_params('foo.example.com', true).and_raise_error(Puppet::ParseError, %r{is not a string}) }
+    it { is_expected.to run.with_params('foo.example.com', []).and_raise_error(ArgumentError, %r{got Array}) }
+    it { is_expected.to run.with_params('foo.example.com', {}).and_raise_error(ArgumentError, %r{got Hash}) }
+    it { is_expected.to run.with_params('foo.example.com', 1).and_raise_error(ArgumentError, %r{got Integer}) }
+    it { is_expected.to run.with_params('foo.example.com', true).and_raise_error(ArgumentError, %r{got Boolean}) }
 
-    it { is_expected.to run.with_params('').and_raise_error(Puppet::ParseError, %r{is not a syntactically correct domain name}) }
-    it { is_expected.to run.with_params('invalid domain').and_raise_error(Puppet::ParseError, %r{is not a syntactically correct domain name}) }
-    it { is_expected.to run.with_params('-foo.example.com').and_raise_error(Puppet::ParseError, %r{is not a syntactically correct domain name}) }
-    it { is_expected.to run.with_params('www.example.2com').and_raise_error(Puppet::ParseError, %r{is not a syntactically correct domain name}) }
-    it { is_expected.to run.with_params('192.168.1.1').and_raise_error(Puppet::ParseError, %r{is not a syntactically correct domain name}) }
+    it { is_expected.to run.with_params('').and_raise_error(ArgumentError, %r{got ''}) }
+    it { is_expected.to run.with_params('invalid domain').and_raise_error(ArgumentError, %r{got 'invalid domain'}) }
+    it { is_expected.to run.with_params('-foo.example.com').and_raise_error(ArgumentError, %r{got '-foo\.example\.com'}) }
+    it { is_expected.to run.with_params('www.example.2com').and_raise_error(ArgumentError, %r{got 'www\.example\.2com'}) }
+    it { is_expected.to run.with_params('192.168.1.1').and_raise_error(ArgumentError, %r{got '192\.168\.1\.1'}) }
   end
 end

spec/type_aliases/dns_zone_spec.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Stdlib::Dns_zone' do
+  describe 'accepts dns zones' do
+    [
+      '.',
+      'com.',
+      'example.com.',
+    ].each do |value|
+      describe value.inspect do
+        it { is_expected.to allow_value(value) }
+      end
+    end
+  end
+
+  describe 'rejects other values' do
+    [
+      true,
+      false,
+      '',
+      'iAmAString',
+      {},
+      { 'key' => 'value' },
+      { 1 => 2 },
+      :undef,
+      3,
+      '2com.',
+      'com2.',
+      'www..com.',
+      '127.0.0.1',
+    ].each do |value|
+      describe value.inspect do
+        it { is_expected.not_to allow_value(value) }
+      end
+    end
+  end
+end

types/dns_zone.pp

@@ -0,0 +1,2 @@
+# @summary Validate a DNS zone name
+type Stdlib::Dns_zone = Pattern[/\A((([[:alnum:]]|[[:alnum:]][[:alnum:]-]*[[:alnum:]])\.)*[[:alpha:]]+\.|\.)\z/]

types/fqdn.pp

@@ -1,2 +1,2 @@
 # @summary Validate a Fully Qualified Domain Name
-type Stdlib::Fqdn = Pattern[/\A(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])\z/]
+type Stdlib::Fqdn = Pattern[/\A((([[:alnum:]]|[[:alnum:]][[:alnum:]-]*[[:alnum:]])\.)*[[:alpha:]]+)\z/]