code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
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  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               The Next Generation Logic Library                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  //                                                                       //
  //  Copyright 2015-20xx Christoph Zengler                                //
  //                                                                       //
  //  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.logicng.knowledgecompilation.bdds;
  
  import static org.assertj.core.api.Assertions.assertThat;
  
  import org.junit.jupiter.api.Test;
  import org.logicng.formulas.Formula;
  import org.logicng.formulas.FormulaFactory;
  import org.logicng.handlers.NumberOfNodesBDDHandler;
  import org.logicng.handlers.TimeoutBDDHandler;
  import org.logicng.io.parsers.ParserException;
  import org.logicng.knowledgecompilation.bdds.jbuddy.BDDKernel;
  import org.logicng.testutils.NQueensGenerator;
  import org.logicng.testutils.PigeonHoleGenerator;
  
  import java.math.BigInteger;
  
  /**
   * Some more extensive tests for BDDs
   * @version 2.0.0
   * @since 1.4.0
   */
  public class LargeBDDTest {
  
      @Test
      public void testPigeonHole() {
          final FormulaFactory f = new FormulaFactory();
          final PigeonHoleGenerator generator = new PigeonHoleGenerator(f);
          testPigeonHole(f, generator, 2);
          testPigeonHole(f, generator, 3);
          testPigeonHole(f, generator, 4);
          testPigeonHole(f, generator, 5);
          testPigeonHole(f, generator, 6);
          testPigeonHole(f, generator, 7);
          testPigeonHole(f, generator, 8);
          testPigeonHole(f, generator, 9);
      }
  
      private void testPigeonHole(final FormulaFactory f, final PigeonHoleGenerator generator, final int size) {
          final Formula pigeon = generator.generate(size);
          final BDDKernel kernel = new BDDKernel(f, pigeon.variables().size(), 10000, 10000);
          final BDD bdd = BDDFactory.build(pigeon, kernel);
          assertThat(bdd.isContradiction()).isTrue();
      }
  
      @Test
      public void testQueens() {
          final FormulaFactory f = new FormulaFactory();
          final NQueensGenerator generator = new NQueensGenerator(f);
          testQueens(f, generator, 4, 2);
          testQueens(f, generator, 5, 10);
          testQueens(f, generator, 6, 4);
          testQueens(f, generator, 7, 40);
          testQueens(f, generator, 8, 92);
      }
  
      private void testQueens(final FormulaFactory f, final NQueensGenerator generator, final int size, final int models) {
          final Formula queens = generator.generate(size);
          final BDDKernel kernel = new BDDKernel(f, queens.variables().size(), 10000, 10000);
          final BDD bdd = BDDFactory.build(queens, kernel);
          final Formula cnf = bdd.cnf();
          assertThat(cnf.isCNF()).isTrue();
          final BDD cnfBDD = BDDFactory.build(cnf, kernel);
          assertThat(cnfBDD).isEqualTo(bdd);
          assertThat(bdd.support()).isEqualTo(queens.variables());
          assertThat(bdd.modelCount()).isEqualTo(BigInteger.valueOf(models));
      }
  
      @Test
      public void testTimeoutBDDHandlerSmall() {
          final FormulaFactory f = new FormulaFactory();
          final NQueensGenerator generator = new NQueensGenerator(f);
          final Formula queens = generator.generate(4);
          final BDDKernel kernel = new BDDKernel(f, queens.variables().size(), 10000, 10000);
          final TimeoutBDDHandler handler = new TimeoutBDDHandler(2000L);
          final BDD bdd = BDDFactory.build(queens, kernel, handler);
          assertThat(handler.aborted()).isFalse();
          assertThat(bdd.index()).isNotEqualTo(BDDKernel.BDD_ABORT);
      }
  
      @Test
      public void testTimeoutBDDHandlerLarge() {
          final FormulaFactory f = new FormulaFactory();
          final NQueensGenerator generator = new NQueensGenerator(f);
          final Formula queens = generator.generate(10);
          final BDDKernel kernel = new BDDKernel(f, queens.variables().size(), 10000, 10000);
          final TimeoutBDDHandler handler = new TimeoutBDDHandler(1000L);
          final BDD bdd = BDDFactory.build(queens, kernel, handler);
          assertThat(handler.aborted()).isTrue();
          assertThat(bdd.index()).isEqualTo(BDDKernel.BDD_ABORT);
      }
  
      @Test
      public void testNumberOfNodesHandlerSmall() {
          final FormulaFactory f = new FormulaFactory();
          final NQueensGenerator generator = new NQueensGenerator(f);
          final Formula queens = generator.generate(4);
          final BDDKernel kernel = new BDDKernel(f, queens.variables().size(), 10000, 10000);
          final NumberOfNodesBDDHandler handler = new NumberOfNodesBDDHandler(1000);
          final BDD bdd = BDDFactory.build(queens, kernel, handler);
          assertThat(handler.aborted()).isFalse();
          assertThat(bdd.index()).isNotEqualTo(BDDKernel.BDD_ABORT);
      }
  
      @Test
      public void testNumberOfNodesHandlerLarge() {
          final FormulaFactory f = new FormulaFactory();
          final NQueensGenerator generator = new NQueensGenerator(f);
          final Formula queens = generator.generate(10);
          final BDDKernel kernel = new BDDKernel(f, queens.variables().size(), 10000, 10000);
          final NumberOfNodesBDDHandler handler = new NumberOfNodesBDDHandler(5);
          final BDD bdd = BDDFactory.build(queens, kernel, handler);
          assertThat(handler.aborted()).isTrue();
          assertThat(bdd.index()).isEqualTo(BDDKernel.BDD_ABORT);
      }
  
      @Test
      public void testNumberOfNodesHandler() throws ParserException {
          final FormulaFactory f = new FormulaFactory();
          final Formula formula = f.parse("A <=> ~(B => C & F & G & ~H | A & D & ~E)");
          final BDDKernel kernel = new BDDKernel(f, formula.variables().size(), 10000, 10000);
          final NumberOfNodesBDDHandler handler = new NumberOfNodesBDDHandler(5);
          final BDD bdd = BDDFactory.build(formula, kernel, handler);
          assertThat(handler.aborted()).isTrue();
          assertThat(bdd.index()).isEqualTo(BDDKernel.BDD_ABORT);
      }
  }
  