add created_at to comment entity

this is a preparation for diaspora/diaspora#4269

lib/diaspora_federation/entities/comment.rb

@@ -14,6 +14,11 @@ module DiasporaFederation
       #   @return [String] the comment text
       property :text
 
+      # @!attribute [r] created_at
+      #   comment entity creation time
+      #   @return [Time] creation time
+      property :created_at, default: -> { Time.now.utc }
+
       # The {Comment} parent is a Post
       # @return [String] parent type
       def parent_type

spec/lib/diaspora_federation/entities/comment_spec.rb

@@ -3,6 +3,7 @@ module DiasporaFederation
     let(:parent) { FactoryGirl.create(:post, author: bob) }
     let(:data) {
       FactoryGirl.build(:comment_entity, author: alice.diaspora_id, parent_guid: parent.guid).send(:xml_elements)
+                 .merge(created_at: Time.now.utc)
     }
 
     let(:xml) {
@@ -20,10 +21,27 @@ XML
 
     it_behaves_like "an Entity subclass"
 
-    it_behaves_like "an XML Entity"
+    it_behaves_like "an XML Entity", [:created_at]
 
     it_behaves_like "a relayable Entity"
 
+    describe "#created_at" do
+      it "has a created_at after parse" do
+        entity = described_class.from_xml(Nokogiri::XML::Document.parse(xml).root)
+        expect(entity.created_at).to be_within(1.second).of(Time.now.utc)
+      end
+
+      it "parses the created_at from the xml if it is included and correctly signed" do
+        created_at = Time.now.utc - 1.minute
+        comment_data = FactoryGirl.build(:comment_entity, author: alice.diaspora_id, parent_guid: parent.guid).to_h
+        comment_data[:created_at] = created_at
+        comment = described_class.new(comment_data, [:author, :guid, :parent_guid, :text, :created_at])
+
+        parsed_comment = described_class.from_xml(comment.to_xml)
+        expect(parsed_comment.created_at).to eq(created_at.to_s)
+      end
+    end
+
     describe "#parent_type" do
       it "returns \"Post\" as parent type" do
         expect(described_class.new(data).parent_type).to eq("Post")

spec/support/shared_entity_specs.rb

@@ -32,7 +32,7 @@ shared_examples "an Entity subclass" do
   end
 end
 
-shared_examples "an XML Entity" do
+shared_examples "an XML Entity" do |ignored_props=[]|
   let(:instance) { described_class.new(data) }
 
   describe "#to_xml" do
@@ -46,13 +46,13 @@ shared_examples "an XML Entity" do
       packed_xml = DiasporaFederation::Salmon::XmlPayload.pack(instance)
       parsed_instance = DiasporaFederation::Salmon::XmlPayload.unpack(packed_xml)
 
-      check_entity(instance, parsed_instance)
+      check_entity(instance, parsed_instance, ignored_props)
     end
   end
 
-  def check_entity(entity, parsed_entity)
+  def check_entity(entity, parsed_entity, ignored_props=[])
     entity.class.class_props.each do |name, type|
-      validate_values(entity.send(name), parsed_entity.send(name), type)
+      validate_values(entity.send(name), parsed_entity.send(name), type) unless ignored_props.include?(name)
     end
   end