//=============================================================================
// 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.Arrays;
import java.util.List;
import org.testng.annotations.Test;
import org.uncommons.watchmaker.framework.factories.StubIntegerFactory;
import org.uncommons.watchmaker.framework.operators.IntegerAdjuster;
import org.uncommons.watchmaker.framework.selection.RouletteWheelSelection;
/**
* Unit test for the {@link SteadyStateEvolutionEngine} class.
* @author Daniel Dyer
*/
public class SteadyStateEvolutionEngineTest
{
/**
* A single iteration should update only a single candidate.
*/
@Test
public void testIncrementalEvolution()
{
SteadyStateEvolutionEngine<Integer> steadyState = new SteadyStateEvolutionEngine<Integer>(new StubIntegerFactory(),
new IntegerAdjuster(5),
new NullFitnessEvaluator(),
new RouletteWheelSelection(),
1,
true,
FrameworkTestUtils.getRNG());
@SuppressWarnings("unchecked")
List<EvaluatedCandidate<Integer>> population = Arrays.asList(new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0));
List<EvaluatedCandidate<Integer>> evaluatedPopulation = steadyState.nextEvolutionStep(population,
0,
FrameworkTestUtils.getRNG());
assert evaluatedPopulation.size() == 5 : "Population size should be unchanged.";
int unchangedCount = 0;
for (EvaluatedCandidate<Integer> candidate : evaluatedPopulation)
{
if (candidate.getCandidate() == 1)
{
++unchangedCount;
}
}
assert unchangedCount == 4 : "Should be 4 out of 5 candidates unchanged, is " + unchangedCount;
}
/**
* Even if the evolutionary operator generates multiple offspring, only a single individual should be
* replaced if the forceSingleUpdate flag is set.
*/
@Test
public void testForcedSingleCandidateUpdate()
{
SteadyStateEvolutionEngine<Integer> steadyState = new SteadyStateEvolutionEngine<Integer>(new StubIntegerFactory(),
new IntegerAdjuster(5),
new NullFitnessEvaluator(),
new RouletteWheelSelection(),
2,
true, // Force single update.
FrameworkTestUtils.getRNG());
@SuppressWarnings("unchecked")
List<EvaluatedCandidate<Integer>> population = Arrays.asList(new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0),
new EvaluatedCandidate<Integer>(1, 0));
List<EvaluatedCandidate<Integer>> evaluatedPopulation = steadyState.nextEvolutionStep(population,
0,
FrameworkTestUtils.getRNG());
assert evaluatedPopulation.size() == 5 : "Population size should be unchanged.";
int unchangedCount = 0;
for (EvaluatedCandidate<Integer> candidate : evaluatedPopulation)
{
if (candidate.getCandidate() == 1)
{
++unchangedCount;
}
}
assert unchangedCount == 4 : "Should be 4 out of 5 candidates unchanged, is " + unchangedCount;
}
@Test
public void testElitism()
{
SteadyStateEvolutionEngine<Integer> steadyState = new SteadyStateEvolutionEngine<Integer>(new StubIntegerFactory(),
new IntegerAdjuster(10),
new NullFitnessEvaluator(),
new RouletteWheelSelection(),
1,
true,
FrameworkTestUtils.getRNG());
@SuppressWarnings("unchecked")
List<EvaluatedCandidate<Integer>> population = Arrays.asList(new EvaluatedCandidate<Integer>(1, 1),
new EvaluatedCandidate<Integer>(2, 2),
new EvaluatedCandidate<Integer>(3, 3),
new EvaluatedCandidate<Integer>(4, 4),
new EvaluatedCandidate<Integer>(5, 5));
// The fittest candidate should always be preserved.
for (int i = 0; i < 20; i++) // Once is not enough to be confident.
{
List<EvaluatedCandidate<Integer>> evaluatedPopulation = steadyState.nextEvolutionStep(population,
1,
FrameworkTestUtils.getRNG());
assert evaluatedPopulation.size() == 5 : "Population size should be unchanged.";
boolean found = false;
for (EvaluatedCandidate<Integer> candidate : evaluatedPopulation)
{
if (candidate.getCandidate() == 5)
{
found = true;
break;
}
}
assert found : "Elite candidate should be preserved.";
}
}
}