add validators for empty arrays

lib/diaspora_federation/validators/conversation_validator.rb

@@ -6,6 +6,8 @@ module DiasporaFederation
 
       rule :guid, :guid
 
+      rule :messages, :not_nil
+
       rule :author, %i(not_empty diaspora_id)
 
       rule :participants, diaspora_id_count: {maximum: 20}

lib/diaspora_federation/validators/status_message_validator.rb

@@ -8,6 +8,8 @@ module DiasporaFederation
 
       rule :guid, :guid
 
+      rule :photos, :not_nil
+
       rule :public, :boolean
     end
   end

spec/lib/diaspora_federation/validators/conversation_validator_spec.rb

@@ -13,7 +13,15 @@ module DiasporaFederation
       let(:property) { :guid }
     end
 
-    describe "participant_ids" do
+    describe "#messages" do
+      it_behaves_like "a property with a value validation/restriction" do
+        let(:property) { :messages }
+        let(:wrong_values) { [nil] }
+        let(:correct_values) { [[], [FactoryGirl.build(:message_entity)]] }
+      end
+    end
+
+    describe "#participant_ids" do
       # must not contain more than 20 participant handles
       it_behaves_like "a property with a value validation/restriction" do
         let(:property) { :participants }

spec/lib/diaspora_federation/validators/status_message_validator_spec.rb

@@ -13,6 +13,14 @@ module DiasporaFederation
       let(:property) { :guid }
     end
 
+    describe "#photos" do
+      it_behaves_like "a property with a value validation/restriction" do
+        let(:property) { :photos }
+        let(:wrong_values) { [nil] }
+        let(:correct_values) { [[], [FactoryGirl.build(:photo_entity)]] }
+      end
+    end
+
     it_behaves_like "a boolean validator" do
       let(:property) { :public }
     end

spec/support/shared_validator_specs.rb

@@ -1,5 +1,6 @@
 def entity_stub(entity, data={})
-  OpenStruct.new(FactoryGirl.attributes_for(entity).merge(data))
+  OpenStruct.new(FactoryGirl.factory_by_name(entity).build_class.default_values
+                   .merge(FactoryGirl.attributes_for(entity)).merge(data))
 end
 
 ALPHANUMERIC_RANGE = [*"0".."9", *"A".."Z", *"a".."z"].freeze