Use instance_eval in Condition::DSL#evaluate:

Use instance_eval so that the assigned block is evaluated inside the
DSL sandbox instance, giving access to all required methods and instance
variables.

lib/producer/core/condition/dsl.rb

@@ -24,7 +24,7 @@ module Producer
         end
 
         def evaluate
-          @block.call
+          instance_eval &@block
         end
       end
     end