content: /**
   * Copyright (c) 2016-2018 Siemens AG
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   * 1) Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 
   * 2) Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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  package at.ac.tuwien.kr.alpha.core.solver.heuristics;
  
  import static at.ac.tuwien.kr.alpha.core.common.NoGoodTest.fromOldLiterals;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Random;
  
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import at.ac.tuwien.kr.alpha.core.common.AtomStore;
  import at.ac.tuwien.kr.alpha.core.common.AtomStoreImpl;
  import at.ac.tuwien.kr.alpha.core.common.NoGood;
  import at.ac.tuwien.kr.alpha.core.solver.NaiveNoGoodStore;
  import at.ac.tuwien.kr.alpha.core.solver.TrailAssignment;
  import at.ac.tuwien.kr.alpha.core.solver.WritableAssignment;
  import at.ac.tuwien.kr.alpha.core.solver.learning.GroundConflictNoGoodLearner.ConflictAnalysisResult;
  import at.ac.tuwien.kr.alpha.core.test.util.TestUtils;
  
  /**
   * Tests {@link BerkMin}.
   * 
   * Copyright (c) 2016 Siemens AG
   *
   */
  public class BerkMinTest {
  	
  	/**
  	 * The tolerable epsilon for double comparisons
  	 */
  	private static final double DOUBLE_COMPARISON_EPSILON = 0.000001;
  	
  	private BerkMin berkmin;
  	
  	@BeforeEach
  	public void setUp() {
  		AtomStore atomStore = new AtomStoreImpl();
  		TestUtils.fillAtomStore(atomStore, 2);
  		WritableAssignment assignment = new TrailAssignment(atomStore);
  		assignment.growForMaxAtomId();
  		this.berkmin = new BerkMin(
  			assignment,
  			new PseudoChoiceManager(assignment, new NaiveNoGoodStore(assignment)),
  			new Random()
  		);
  	}
  	
  	@Test
  	public void countPositiveLiteralsOnce() {
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(1, 2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void countNegativeLiteralsOnce() {
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(-1, -2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(-1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(-2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void countPositiveLiteralsTwice() {
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(1, 2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void countNegativeLiteralsTwice() {
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(-1, -2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(-1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(-2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void countMixedLiteralsTwice() {
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(1, -2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(-2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void countPositiveLiteralsThenNegativeLiterals() {
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(1, 2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		violatedNoGood = new NoGood(fromOldLiterals(-1, -2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void reachDecayPeriodOnce() {
  		berkmin.setDecayPeriod(3);
  		berkmin.setDecayFactor(1.0 / 3);
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(1, 2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void reachDecayPeriodTwice() {
  		berkmin.setDecayPeriod(2);
  		berkmin.setDecayFactor(0.75);
  		NoGood violatedNoGood = new NoGood(fromOldLiterals(1, 2));
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(1, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(1.5, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(1.5, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2.5, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2.5, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  		berkmin.violatedNoGood(violatedNoGood);
  		berkmin.analyzedConflict(pseudo(violatedNoGood));
  		assertEquals(2.625, berkmin.getActivity(fromOldLiterals(1)), DOUBLE_COMPARISON_EPSILON);
  		assertEquals(2.625, berkmin.getActivity(fromOldLiterals(2)), DOUBLE_COMPARISON_EPSILON);
  	}
  	
  	@Test
  	public void learnNoGood() {
  		NoGood learnedNoGood = NoGood.learnt(fromOldLiterals(1, 2));
  		int backjumpLevel = 1;
  		@SuppressWarnings("unused")
  		boolean clearLastChoiceAfterBackjump = true;
  		Collection<Integer> resolutionAtoms = Collections.emptySet();
  		berkmin.analyzedConflict(new ConflictAnalysisResult(learnedNoGood, backjumpLevel,
  			resolutionAtoms));
  		assertEquals(learnedNoGood, berkmin.getCurrentTopClause());
  	}
  
  	private static ConflictAnalysisResult pseudo(NoGood noGood) {
  		return new ConflictAnalysisResult(noGood, 0, Collections.emptySet());
  	}
  }
  