Ensure Sidekiq.enable_delay! does not break Psych.

lib/sidekiq/delay.rb

@@ -24,7 +24,7 @@ module Sidekiq
 
     module PsychAutoload
       def resolve_class(klass_name)
-        return klass_name unless klass_name
+        return nil if !klass_name || klass_name.empty?
         # constantize
         names = klass_name.split('::')
         names.shift if names.empty? || names.first.empty?

test/test_extensions.rb

@@ -110,6 +110,11 @@ class TestExtensions < Sidekiq::Test
       assert_equal 1, q.size
     end
 
+    it 'allows Psych to serialize anonymous structs' do
+      obj = Struct.new(:attribute).new(my: 'data')
+
+      assert_equal obj.attribute, Psych.load(Psych.dump(obj)).attribute
+    end
   end
 
 end