set nil if parsing an empty string

lib/diaspora_federation/entity.rb

@@ -50,7 +50,7 @@ module DiasporaFederation
       end
 
       self.class.default_values.merge(data).each do |k, v|
-        instance_variable_set("@#{k}", v) if setable?(k, v)
+        instance_variable_set("@#{k}", nilify(v)) if setable?(k, v)
       end
       freeze
     end
@@ -113,6 +113,11 @@ module DiasporaFederation
         val.all? {|v| v.instance_of?(t.first) })
     end
 
+    def nilify(value)
+      return nil if value.respond_to?(:empty?) && value.empty?
+      value
+    end
+
     # Serialize the Entity into XML elements
     # @return [Nokogiri::XML::Element] root node
     def entity_xml

spec/lib/diaspora_federation/discovery/h_card_spec.rb

@@ -152,6 +152,25 @@ HTML
         expect(hcard.searchable).to eq(false)
       end
 
+      it "name is nil if empty" do
+        changed_html = html.sub(
+          "class=\"fn\">#{person.full_name}<",
+          "class=\"fn\"><"
+        ).sub(
+          "class=\"given_name\">#{person.first_name}<",
+          "class=\"given_name\"><"
+        ).sub(
+          "class=\"family_name\">#{person.last_name}<",
+          "class=\"family_name\"><"
+        )
+
+        hcard = Discovery::HCard.from_html(changed_html)
+
+        expect(hcard.full_name).to be_nil
+        expect(hcard.first_name).to be_nil
+        expect(hcard.last_name).to be_nil
+      end
+
       it "reads old-style HTML" do
         historic_html = <<-HTML
 <div id="content">

spec/lib/diaspora_federation/entity_spec.rb

@@ -20,17 +20,24 @@ module DiasporaFederation
 
       it "sets the defaults" do
         entity = Entities::TestDefaultEntity.new(test1: 1, test2: 2)
-        expect(entity.to_h[:test3]).to be_truthy
+        expect(entity.test3).to be_truthy
       end
 
       it "handles callable defaults" do
         entity = Entities::TestDefaultEntity.new(test1: 1, test2: 2)
-        expect(entity.to_h[:test4]).to be_truthy
+        expect(entity.test4).to be_truthy
       end
 
       it "uses provided values over defaults" do
         entity = Entities::TestDefaultEntity.new(data)
-        expect(entity.to_h[:test3]).to be_falsey
+        expect(entity.test3).to be_falsey
+        expect(entity.test4).to be_falsey
+      end
+
+      it "sets nil if string is empty" do
+        data[:test1] = ""
+        entity = Entities::TestDefaultEntity.new(data)
+        expect(entity.test1).to be_nil
       end
     end