001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.math.genetics;
018    
019    import static org.junit.Assert.*;
020    import org.junit.Test;
021    
022    public class TournamentSelectionTest {
023        
024        private static int counter = 0;
025    
026        @Test
027        public void testSelect() {
028            TournamentSelection ts = new TournamentSelection(2);
029            ElitisticListPopulation pop = new ElitisticListPopulation(100, 0.203);
030            
031            for (int i=0; i<pop.getPopulationLimit(); i++) {
032                pop.addChromosome(new DummyChromosome());
033            }
034            // how to write a test for stochastic method?
035            for (int i=0; i<20; i++) {
036                ChromosomePair pair = ts.select(pop);
037                // the worst chromosome should NEVER be selected
038                assertTrue(pair.getFirst().getFitness() > 0);
039                assertTrue(pair.getSecond().getFitness() > 0);
040            }
041        }
042        
043        private static class DummyChromosome extends Chromosome {
044            private final int fitness;
045            
046            public DummyChromosome() {
047                this.fitness = counter;
048                counter++;
049            }
050            
051            public double fitness() {            
052                return this.fitness;
053            }
054        }
055    
056    }