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//=============================================================================
// Copyright 2006-2010 Daniel W. Dyer
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//=============================================================================
package org.uncommons.watchmaker.examples.travellingsalesman;
import java.util.Arrays;
import java.util.List;
import org.testng.annotations.Test;
import org.uncommons.watchmaker.framework.selection.TruncationSelection;
/**
* Unit test for the evolutionary approach to the travelling salesman problem.
* This test does not check that the correct result is returned (we would need
* to run the full evolutionary algorithm for that, and even then optimality
* is not guaranteed). This just ensures that nothing invalid happens and
* provides coverage for the classes involved.
* @author Daniel Dyer
*/
public class EvolutionaryTravellingSalesmanTest
{
private final DistanceLookup data = new TestDistances();
/**
* Ensure that the algorithm behaves when configured to use mutation.
*/
@Test
public void testWithMutation()
{
TravellingSalesmanStrategy strategy = new EvolutionaryTravellingSalesman(data,
new TruncationSelection(0.5),
10, // Small population.
0, // No elitism.
3, // Only a few generations.
false, // Cross-over.
true); // Mutation.
List<String> cities = Arrays.asList("City1", "City2", "City3", "City4");
List<String> route = strategy.calculateShortestRoute(cities, null);
assert route.size() == 4 : "Route is wrong length: " + route.size();
assert route.contains("City1") : "Route does not contain City1.";
assert route.contains("City2") : "Route does not contain City2.";
assert route.contains("City3") : "Route does not contain City3.";
assert route.contains("City4") : "Route does not contain City4.";
}
/**
* Ensure that the algorithm behaves when configured to use cross-over.
*/
@Test
public void testWithCrossover()
{
TravellingSalesmanStrategy strategy = new EvolutionaryTravellingSalesman(data,
new TruncationSelection(0.5),
10, // Small population.
0, // No elitism.
3, // Only a few generations.
true, // Cross-over
false); // Mutation.
List<String> cities = Arrays.asList("City1", "City2", "City3", "City4");
List<String> route = strategy.calculateShortestRoute(cities, null);
assert route.size() == 4 : "Route is wrong length: " + route.size();
assert route.contains("City1") : "Route does not contain City1.";
assert route.contains("City2") : "Route does not contain City2.";
assert route.contains("City3") : "Route does not contain City3.";
assert route.contains("City4") : "Route does not contain City4.";
}
/**
* The strategy must ensure that at least one of cross-over or mutation is chosen.
*/
@Test(expectedExceptions = IllegalArgumentException.class)
public void testNoEvolution()
{
new EvolutionaryTravellingSalesman(data,
new TruncationSelection(0.5),
10,
0,
3,
false,
false); // Should throw an IllegalArgumentException as no operators are enabled.
}
}
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