CoverageCrossOver.java example

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/**
 * Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
 */
/**
 * 
 */
package org.evosuite.ga.operators.crossover;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.evosuite.ga.Chromosome;
import org.evosuite.ga.ConstructionFailedException;
import org.evosuite.testcase.TestChromosome;
import org.evosuite.testcase.TestFitnessFunction;
import org.evosuite.testsuite.TestSuiteChromosome;
import org.evosuite.utils.Randomness;


/**
 * <p>CoverageCrossOver class.</p>
 *
 * @author Gordon Fraser
 */
public class CoverageCrossOver extends CrossOverFunction {

	private static final long serialVersionUID = -2203276450790663024L;

	/* (non-Javadoc)
	 * @see org.evosuite.ga.CrossOverFunction#crossOver(org.evosuite.ga.Chromosome, org.evosuite.ga.Chromosome)
	 */
	/** {@inheritDoc} */
	@Override
	public void crossOver(Chromosome parent1, Chromosome parent2)
	        throws ConstructionFailedException {
		assert (parent1 instanceof TestSuiteChromosome);
		assert (parent2 instanceof TestSuiteChromosome);

		TestSuiteChromosome suite1 = (TestSuiteChromosome) parent1;
		TestSuiteChromosome suite2 = (TestSuiteChromosome) parent2;

		// Determine coverage information
		Map<TestFitnessFunction, Set<TestChromosome>> goalMap = new HashMap<TestFitnessFunction, Set<TestChromosome>>();
		populateCoverageMap(goalMap, suite1);
		populateCoverageMap(goalMap, suite2);

		// Extract set of tests that have unique coverage
		// We need all of these tests in both offspring
		Set<TestChromosome> unique = removeUniqueCoveringTests(goalMap);
		logger.debug("Uniquely covering tests: " + unique.size());

		Set<TestChromosome> offspring1 = new HashSet<TestChromosome>();
		Set<TestChromosome> offspring2 = new HashSet<TestChromosome>();
		Set<TestChromosome> workingSet = new HashSet<TestChromosome>();
		for (TestFitnessFunction goal : goalMap.keySet()) {
			workingSet.addAll(goalMap.get(goal));
		}

		int targetSize = workingSet.size() / 2;
		while (offspring2.size() < targetSize) {
			logger.debug("Sizes: " + workingSet.size() + ", " + offspring1.size() + ", "
			        + offspring2.size());

			// Move a randomly selected redundant test case t from workingset to offspring2
			TestChromosome choice = Randomness.choice(workingSet);
			workingSet.remove(choice);
			offspring2.add(choice);

			// Move all tests with unique coverage to offspring 1?
			offspring1.addAll(removeUniqueCoveringTests(goalMap));
		}

		offspring1.addAll(workingSet);

		suite1.clearTests();
		suite2.clearTests();

		// Add unique tests
		for (TestChromosome test : unique) {
			suite1.addTest((TestChromosome) test.clone());
			suite2.addTest((TestChromosome) test.clone());
		}

		// Add redundancy tests
		suite1.addTests(offspring1);
		suite2.addTests(offspring2);
		logger.debug("Final sizes: " + suite1.size() + ", " + suite2.size());

	}

	/**
	 * Create a map from coverage goal to tests that cover this goal
	 * 
	 * @param goalMap
	 * @param suite
	 */
	private void populateCoverageMap(
	        Map<TestFitnessFunction, Set<TestChromosome>> goalMap,
	        TestSuiteChromosome suite) {
		for (TestChromosome test : suite.getTestChromosomes()) {
			for (TestFitnessFunction goal : test.getTestCase().getCoveredGoals()) {
				if (!goalMap.containsKey(goal))
					goalMap.put(goal, new HashSet<TestChromosome>());
				goalMap.get(goal).add(test);
			}

		}
	}

	private Set<TestChromosome> removeUniqueCoveringTests(
	        Map<TestFitnessFunction, Set<TestChromosome>> goalMap) {
		Set<TestChromosome> tests = new HashSet<TestChromosome>();
		Set<TestFitnessFunction> uniqueGoals = new HashSet<TestFitnessFunction>();
		for (Entry<TestFitnessFunction, Set<TestChromosome>> entry : goalMap.entrySet()) {
			if (entry.getValue().size() == 1) {
				uniqueGoals.add(entry.getKey());
				tests.add(entry.getValue().iterator().next());
			}
		}
		uniqueGoals.removeAll(uniqueGoals);
		return tests;
	}

}