code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
  //                / /___/ /_/ / /_/ / / /__/ /|  / /_/ /                 //
  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               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.cardinalityconstraints;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.BEST;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.BIMANDER;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.BINARY;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.COMMANDER;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.LADDER;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.NESTED;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.PRODUCT;
  import static org.logicng.cardinalityconstraints.CCConfig.AMO_ENCODER.PURE;
  import static org.logicng.cardinalityconstraints.CCConfig.BIMANDER_GROUP_SIZE.FIXED;
  import static org.logicng.cardinalityconstraints.CCConfig.BIMANDER_GROUP_SIZE.HALF;
  import static org.logicng.cardinalityconstraints.CCConfig.BIMANDER_GROUP_SIZE.SQRT;
  
  import org.junit.jupiter.api.Test;
  import org.logicng.LogicNGTest;
  import org.logicng.formulas.CardinalityConstraint;
  import org.logicng.formulas.Formula;
  import org.logicng.formulas.FormulaFactory;
  import org.logicng.formulas.Variable;
  import org.logicng.solvers.MiniSat;
  import org.logicng.solvers.SATSolver;
  
  /**
   * Unit tests for the at-most-one configs.
   * @version 2.0.0
   * @since 1.0
   */
  public class CCAMOTest implements LogicNGTest {
  
      private final CCConfig[] configs;
  
      public CCAMOTest() {
          this.configs = new CCConfig[14];
          this.configs[0] = CCConfig.builder().amoEncoding(PURE).build();
          this.configs[1] = CCConfig.builder().amoEncoding(LADDER).build();
          this.configs[2] = CCConfig.builder().amoEncoding(PRODUCT).build();
          this.configs[3] = CCConfig.builder().amoEncoding(BINARY).build();
          this.configs[4] = CCConfig.builder().amoEncoding(NESTED).build();
          this.configs[5] = CCConfig.builder().amoEncoding(COMMANDER).commanderGroupSize(3).build();
          this.configs[6] = CCConfig.builder().amoEncoding(COMMANDER).commanderGroupSize(7).build();
          this.configs[7] = CCConfig.builder().amoEncoding(BIMANDER).bimanderGroupSize(FIXED).build();
          this.configs[8] = CCConfig.builder().amoEncoding(BIMANDER).bimanderGroupSize(HALF).build();
          this.configs[9] = CCConfig.builder().amoEncoding(BIMANDER).bimanderGroupSize(SQRT).build();
          this.configs[10] = CCConfig.builder().amoEncoding(BIMANDER).bimanderGroupSize(FIXED).bimanderFixedGroupSize(2).build();
          this.configs[11] = CCConfig.builder().amoEncoding(NESTED).nestingGroupSize(5).build();
          this.configs[12] = CCConfig.builder().amoEncoding(PRODUCT).productRecursiveBound(10).build();
          this.configs[13] = CCConfig.builder().amoEncoding(BEST).build();
      }
  
      @Test
      public void testAMO0() {
          final FormulaFactory f = new FormulaFactory();
          final Formula cc = f.amo();
          assertThat(cc).isEqualTo(f.verum());
      }
  
      @Test
      public void testAMO1() {
          final FormulaFactory f = new FormulaFactory();
          final CardinalityConstraint cc = (CardinalityConstraint) f.amo(f.variable("v0"));
          for (final CCConfig config : this.configs) {
              assertThat(new CCEncoder(f, config).encode(cc)).isEmpty();
          }
          assertThat(f.newCCVariable().name()).endsWith("_0");
      }
  
      @Test
      public void testAMOK() {
          final FormulaFactory f = new FormulaFactory();
          int counter = 0;
          for (final CCConfig config : this.configs) {
              if (config != null) {
                  f.putConfiguration(config);
                  testAMO(2, f, false);
                  testAMO(10, f, false);
                  testAMO(100, f, false);
                  testAMO(250, f, false);
                  testAMO(500, f, false);
                  assertThat(f.newCCVariable().name()).endsWith("_" + counter++);
              }
          }
      }
  
      @Test
      public void testAMOKMiniCard() {
          final FormulaFactory f = new FormulaFactory();
          testAMO(2, f, true);
          testAMO(10, f, true);
          testAMO(100, f, true);
          testAMO(250, f, true);
          testAMO(500, f, true);
          assertThat(f.newCCVariable().name()).endsWith("_0");
      }
  
      @Test
      public void testToString() {
          assertThat(this.configs[0].amoEncoder.toString()).isEqualTo("PURE");
          assertThat(this.configs[1].amoEncoder.toString()).isEqualTo("LADDER");
          assertThat(this.configs[2].amoEncoder.toString()).isEqualTo("PRODUCT");
          assertThat(this.configs[3].amoEncoder.toString()).isEqualTo("BINARY");
          assertThat(this.configs[4].amoEncoder.toString()).isEqualTo("NESTED");
          assertThat(this.configs[5].amoEncoder.toString()).isEqualTo("COMMANDER");
          assertThat(this.configs[7].amoEncoder.toString()).isEqualTo("BIMANDER");
          assertThat(this.configs[13].amoEncoder.toString()).isEqualTo("BEST");
          assertThat(new CCAMOPure().toString()).isEqualTo("CCAMOPure");
          assertThat(new CCAMOLadder().toString()).isEqualTo("CCAMOLadder");
          assertThat(new CCAMOProduct(2).toString()).isEqualTo("CCAMOProduct");
          assertThat(new CCAMOBinary().toString()).isEqualTo("CCAMOBinary");
          assertThat(new CCAMONested(2).toString()).isEqualTo("CCAMONested");
          assertThat(new CCAMOCommander(2).toString()).isEqualTo("CCAMOCommander");
          assertThat(new CCAMOBimander(2).toString()).isEqualTo("CCAMOBimander");
  
          assertThat(CCConfig.AMO_ENCODER.values()).contains(CCConfig.AMO_ENCODER.valueOf("LADDER"));
          assertThat(CCConfig.BIMANDER_GROUP_SIZE.values()).contains(CCConfig.BIMANDER_GROUP_SIZE.valueOf("SQRT"));
      }
  
      private void testAMO(final int numLits, final FormulaFactory f, final boolean miniCard) {
          final Variable[] problemLits = new Variable[numLits];
          for (int i = 0; i < numLits; i++) {
              problemLits[i] = f.variable("v" + i);
          }
          final SATSolver solver = miniCard ? MiniSat.miniCard(f) : MiniSat.miniSat(f);
          solver.add(f.amo(problemLits));
          assertSolverSat(solver);
          assertThat(solver.enumerateAllModels(problemLits))
                  .hasSize(numLits + 1)
                  .allMatch(m -> m.positiveVariables().size() <= 1);
      }
  }
  