(PDK-508) implement autorequire and friends

The spec/classes/autorequire_cycle_spec.rb test shows that the
autorelations implementation of the Resource API does build relations.
Since rspec-puppet doesn't provide matching on compile errors, this
builds a test case that compiles when make_cycle is false, thereby
proving that there is no error in the manifest, but fails with a
dependency cycle error when make_cycle is set to true.

lib/puppet/resource_api.rb

@@ -216,6 +216,24 @@ def my_provider
       def context
         self.class.context
       end
+
+      [:autorequire, :autobefore, :autosubscribe, :autonotify].each do |auto|
+        next unless definition[auto]
+
+        definition[auto].each do |type, values|
+          Puppet.debug("Registering #{auto} for #{type}: #{values.inspect}")
+          send(auto, type.downcase.to_sym) do
+            [values].flatten.map do |v|
+              match = %r{\A\$(.*)\Z}.match(v) if v.is_a? String
+              if match.nil?
+                v
+              else
+                self[match[1].to_sym]
+              end
+            end
+          end
+        end
+      end
     end
   end
   module_function :register_type

spec/classes/autorequire_cycle_spec.rb

@@ -1,5 +1,14 @@
 require 'spec_helper'
 
 RSpec.describe 'test_module::autorequire_cycle' do
-  it { is_expected.to compile }
+  context 'with make_cycle => false' do
+    let(:params) { { make_cycle: false } }
+
+    it { is_expected.to compile }
+  end
+  context 'with make_cycle => true' do
+    let(:params) { { make_cycle: true } }
+
+    it { is_expected.not_to compile }
+  end
 end

spec/fixtures/test_module/lib/puppet/type/test_autorequire.rb

@@ -17,5 +17,13 @@
       desc:      'The name of the resource you want to manage.',
       behaviour: :namevar,
     },
+    target:      {
+      type:      'String',
+      desc:      'The resource to autorequire.',
+      behaviour: :parameter,
+    },
+  },
+  autorequire: {
+    test_autorequire: '$target',
   },
 )

spec/fixtures/test_module/manifests/autorequire_cycle.pp

@@ -1,10 +1,23 @@
 # test_module::autorequire_cycle
 #
-# A description of what this class does
+# This class is used to test autorequires.
+# With make_cycle set to false, this should compile without errors or cycles. When make_cycle is set to true, autorequires will be used to
+# construct a dependency cycle. This makes it possible to test exactly the function of the autorequires implementation.
 #
-# @summary A short summary of the purpose of this class
+# @summary This class is used to test autorequires.
 #
 # @example
 #   include test_module::autorequire_cycle
-class test_module::autorequire_cycle {
+class test_module::autorequire_cycle (
+  Boolean $make_cycle
+) {
+  test_autorequire { "a":
+    target => "b",
+  }
+  test_autorequire { "b":
+    target => "c",
+  }
+  test_autorequire { "c":
+    target => $make_cycle ? { true => "a", false => undef },
+  }
 }

spec/fixtures/test_module/spec/classes/autorequire_cycle_spec.rb

@@ -1,11 +1,14 @@
 require 'spec_helper'
 
-describe 'test_module::autorequire_cycle' do
-  on_supported_os.each do |os, os_facts|
-    context "on #{os}" do
-      let(:facts) { os_facts }
+RSpec.describe 'test_module::autorequire_cycle' do
+  context 'with make_cycle => false' do
+    let(:params) { { make_cycle: false } }
 
-      it { is_expected.to compile }
-    end
+    it { is_expected.to compile }
+  end
+  context 'with make_cycle => true' do
+    let(:params) { { make_cycle: true } }
+
+    it { is_expected.not_to compile }
   end
 end

spec/puppet/resource_api_spec.rb

@@ -73,6 +73,18 @@
             desc: 'a optional string value',
           },
         },
+        autorequire: {
+          var: '$test_string',
+        },
+        autobefore: {
+          const: 'value',
+        },
+        autosubscribe: {
+          list: %w[foo bar],
+        },
+        autonotify: {
+          mixed: [10, '$test_integer'],
+        },
       }
     end
 
@@ -84,6 +96,45 @@
       it { is_expected.not_to be_nil }
       it { expect(type.properties.first.doc).to match %r{the description} }
       it { expect(type.properties.first.name).to eq :test_string }
+
+      def extract_values(function)
+        result = []
+        type.send(function) do |_type, values|
+          # rely on the fact that the resource api is doing `self[]` internally to find the value
+          # see https://github.com/puppetlabs/puppet/blob/9f2c143962803a72c68f35be3462944e851bcdce/lib/puppet/type.rb#L2143
+          # for details
+          result += { test_string: 'foo', test_integer: 100 }.instance_eval(&values)
+        end
+        result
+      end
+
+      describe 'autorequire' do
+        it('yields the block for `var`') { expect { |b| type.eachautorequire(&b) }.to yield_with_args(:var, be_a(Proc)) }
+        it 'the yielded block returns the `test_string` value' do
+          expect(extract_values(:eachautorequire)).to eq ['foo']
+        end
+      end
+
+      describe 'autobefore' do
+        it('yields the block for `const`') { expect { |b| type.eachautobefore(&b) }.to yield_with_args(:const, be_a(Proc)) }
+        it('the yielded block returns the constant "value"') do
+          expect(extract_values(:eachautobefore)).to eq ['value']
+        end
+      end
+
+      describe 'autosubscribe' do
+        it('yields the block for `list`') { expect { |b| type.eachautosubscribe(&b) }.to yield_with_args(:list, be_a(Proc)) }
+        it('the yielded block returns the multiple values') do
+          expect(extract_values(:eachautosubscribe)).to eq %w[foo bar]
+        end
+      end
+
+      describe 'autonotify' do
+        it('yields the block for `mixed`') { expect { |b| type.eachautonotify(&b) }.to yield_with_args(:mixed, be_a(Proc)) }
+        it('the yielded block returns multiple integer values') do
+          expect(extract_values(:eachautonotify)).to eq [10, 100]
+        end
+      end
     end
 
     describe 'an instance of this type' do