Initialize empty set of perturbations and add debug messages

app/services/vns/engine.rb

@@ -20,6 +20,11 @@ module VNS
       @optimizations << klass
     end
 
+    def add_perturbation(klass)
+      @perturbations ||= Set.new
+      @perturbations << klass
+    end
+
     attr_writer :initial_solution
 
     def run
@@ -27,13 +32,18 @@ module VNS
       raise 'No optimizations defined' unless @optimizations
       raise 'No initial solution defined' unless @initial_solution
 
+      @perturbations ||= Set.new
+
       @best_solution = @initial_solution
       @best_score = @target_function.call(@best_solution)
 
       self.class.sequence(@optimizations).each do |optimization|
         optimize(optimization)
+        Rails.logger.debug { "Finished optimization phase: #{optimization.name}" }
       end
 
+      Rails.logger.debug { "Finished all optimization phases" }
+
       @best_solution
     end