allow photo.status_message_guid to be nil

lib/diaspora_federation/validators/photo_validator.rb

@@ -14,7 +14,7 @@ module DiasporaFederation
 
       rule :remote_photo_name, :not_empty
 
-      rule :status_message_guid, :guid
+      rule :status_message_guid, guid: {nilable: true}
 
       rule :height, :numeric
 

spec/lib/diaspora_federation/validators/photo_validator_spec.rb

@@ -9,12 +9,18 @@ module DiasporaFederation
       let(:mandatory) { true }
     end
 
-    %i(guid status_message_guid).each do |prop|
-      describe "##{prop}" do
+    describe "#guid" do
       it_behaves_like "a guid validator" do
-          let(:property) { prop }
+        let(:property) { :guid }
       end
     end
+
+    describe "#status_message_guid" do
+      it_behaves_like "a property with a value validation/restriction" do
+        let(:property) { :status_message_guid }
+        let(:wrong_values) { ["aaaaaa", "zzz+-#*$$", ""] }
+        let(:correct_values) { ["1234567890ABCDefgh_ijkl-mnopQR@example.com:3000", nil] }
+      end
     end
 
     it_behaves_like "a boolean validator" do