(MODULES-9049) Add type alias for 'yes' and 'no'.

Author: ghoneycutt

README.md

@@ -670,6 +670,10 @@ Match an IPv6 address which may contain `::` used to compress zeros as documente
 Match an IPv6 address in the CIDR format. It will only match if the address contains an address prefix (for example, it will match   'FF01:0:0:0:0:0:0:101/32', 'FF01::101/60', '::/0',
 but not 'FF01:0:0:0:0:0:0:101', 'FF01::101', '::').
 
+#### `Stdlib::Yes_no`
+
+Match the strings `'yes'` and `'no'`.
+
 <a id="facts"></a>
 ### Facts
 

spec/type_aliases/yes_no_spec.rb

@@ -0,0 +1,40 @@
+# coding: utf-8
+
+require 'spec_helper'
+
+describe 'Stdlib::Yes_no' do
+  describe 'valid types' do
+    [
+      'yes',
+      'no',
+    ].each do |value|
+      describe value.inspect do
+        it { is_expected.to allow_value(value) }
+      end
+    end
+  end
+
+  describe 'invalid types' do
+    context 'with garbage inputs' do
+      [
+        true,
+        false,
+        :keyword,
+        nil,
+        ['yes', 'no'],
+        { 'foo' => 'bar' },
+        {},
+        '',
+        'ネット',
+        '55555',
+        '0x123',
+        'yess',
+        'nooo',
+      ].each do |value|
+        describe value.inspect do
+          it { is_expected.not_to allow_value(value) }
+        end
+      end
+    end
+  end
+end

types/yes_no.pp

@@ -0,0 +1 @@
+type Stdlib::Yes_no = Enum['yes', 'no']