//=============================================================================
// 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.framework;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;
import org.uncommons.watchmaker.framework.factories.StubIntegerFactory;
import org.uncommons.watchmaker.framework.selection.RouletteWheelSelection;
import org.uncommons.watchmaker.framework.termination.ElapsedTime;
import org.uncommons.watchmaker.framework.termination.GenerationCount;
/**
* Unit test for the {@link GenerationalEvolutionEngine} class.
* @author Daniel Dyer
*/
public class GenerationalEvolutionEngineTest
{
private EvolutionEngine<Integer> engine;
@BeforeMethod
public void prepareEngine()
{
this.engine = new GenerationalEvolutionEngine<Integer>(new StubIntegerFactory(),
new IntegerZeroMaker(),
new IntegerEvaluator(),
new RouletteWheelSelection(),
FrameworkTestUtils.getRNG());
}
@Test
public void testElitism()
{
class ElitismObserver implements EvolutionObserver<Integer>
{
private PopulationData<? extends Integer> data;
public void populationUpdate(PopulationData<? extends Integer> data)
{
this.data = data;
}
public double getAverageFitness()
{
return data.getMeanFitness();
}
}
ElitismObserver observer = new ElitismObserver();
engine.addEvolutionObserver(observer);
List<Integer> elite = new ArrayList<Integer>(3);
// Add the following seed candidates, all better than any others that can possibly
// get into the population (since every other candidate will always be zero).
elite.add(7); // This candidate should be discarded by elitism.
elite.add(11);
elite.add(13);
engine.evolve(10,
2,
elite,
new GenerationCount(2)); // Do at least 2 generations because the first is just the initial population.
// Then when we have run the evolution, if the elite canidates were preserved they will
// lift the average fitness above zero. The exact value of the expected average fitness
// is easy to calculate, it is the aggregate fitness divided by the population size.
assert observer.getAverageFitness() == 24d / 10 : "Elite candidates not preserved correctly: " + observer.getAverageFitness();
engine.removeEvolutionObserver(observer);
}
/**
* The number of candidates preserved by elitism must be less than the total
* population size.
*/
@Test(expectedExceptions = IllegalArgumentException.class)
public void testEliteCountTooHigh()
{
engine.evolve(10, 10, new GenerationCount(10)); // Should throw exception because elite is too big.
}
@Test(expectedExceptions = IllegalArgumentException.class)
public void testEliteCountTooLow()
{
engine.evolvePopulation(10, -1, new GenerationCount(10)); // Should throw exception because elite is negative.
}
@Test(expectedExceptions = IllegalArgumentException.class)
public void testNoTerminationConditions()
{
engine.evolve(10, 0); // Should throw exception because there are no termination conditions.
}
@Test
public void testInterrupt()
{
final long timeout = 1000L;
final Thread requestThread = Thread.currentThread();
engine.addEvolutionObserver(new EvolutionObserver<Integer>()
{
public void populationUpdate(PopulationData<? extends Integer> populationData)
{
if (populationData.getElapsedTime() > timeout / 2)
{
requestThread.interrupt();
}
}
});
long startTime = System.currentTimeMillis();
engine.evolve(10, 0, new ElapsedTime(timeout));
long elapsedTime = System.currentTimeMillis() - startTime;
assert Thread.interrupted() : "Thread was not interrupted before timeout.";
assert elapsedTime < timeout : "Engine did not respond to interrupt before timeout.";
assert engine.getSatisfiedTerminationConditions().isEmpty()
: "Interrupted engine should have no satisfied termination conditions.";
}
@Test
public void testGetSatisfiedTerminationConditions()
{
GenerationCount generationsCondition = new GenerationCount(1);
engine.evolve(10, 0, generationsCondition);
List<TerminationCondition> satisfiedConditions = engine.getSatisfiedTerminationConditions();
assert satisfiedConditions.size() == 1 : "Wrong number of conditions: " + satisfiedConditions.size();
assert satisfiedConditions.get(0) == generationsCondition : "Wrong condition returned.";
}
@Test(expectedExceptions = IllegalStateException.class)
public void testGetSatisfiedTerminationConditionsBeforeStart()
{
// Should throw an IllegalStateException because evolution hasn't started, let alone terminated.
engine.getSatisfiedTerminationConditions();
}
/**
* Trivial test operator that mutates all integers into zeroes.
*/
private static final class IntegerZeroMaker implements EvolutionaryOperator<Integer>
{
public List<Integer> apply(List<Integer> selectedCandidates, Random rng)
{
List<Integer> result = new ArrayList<Integer>(selectedCandidates.size());
for (int i = 0; i < selectedCandidates.size(); i++)
{
result.add(0);
}
return result;
}
}
}