add NoImprovement

lib/alns/stop/no_improvement.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require 'alns/stop/base'
+
+module ALNS
+  module Stop
+    class NoImprovement < Base
+      def initialize(max_iterations)
+        super()
+        @max_iterations = max_iterations
+        @target = nil
+        @counter = 0
+      end
+
+      def done?(_rnd, best, _current)
+        if @target.nil? || best.objective < @target
+          @target = best.objective
+          @counter = 0
+        else
+          @counter += 1
+        end
+        @counter >= @max_iterations
+      end
+    end
+  end
+end

test/stop/no_improvement_test.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../models'
+require 'minitest/autorun'
+require 'alns/stop/no_improvement'
+
+class NoImprovementTest < Minitest::Test
+  def test_done?
+    stop = ALNS::Stop::NoImprovement.new(2)
+
+    assert !stop.done?(nil, FakeState.new(2), nil)
+    assert !stop.done?(nil, FakeState.new(2), nil)
+    assert !stop.done?(nil, FakeState.new(1), nil)
+    assert !stop.done?(nil, FakeState.new(1), nil)
+    assert stop.done?(nil, FakeState.new(1), nil)
+  end
+end