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.predicates;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.assertj.core.api.Assertions.assertThatThrownBy;
  import static org.logicng.formulas.cache.PredicateCacheEntry.IS_CNF;
  
  import org.junit.jupiter.api.Test;
  import org.logicng.TestWithExampleFormulas;
  
  /**
   * Unit tests for the cnf predicate.
   * @version 2.0.0
   * @since 1.0
   */
  public class CNFPredicateTest extends TestWithExampleFormulas {
  
      private final CNFPredicate cnfPredicate = CNFPredicate.get();
  
      @Test
      public void test() {
          assertThat(this.f.verum().holds(this.cnfPredicate)).isTrue();
          assertThat(this.f.falsum().holds(this.cnfPredicate)).isTrue();
          assertThat(this.A.holds(this.cnfPredicate)).isTrue();
          assertThat(this.NA.holds(this.cnfPredicate)).isTrue();
          assertThat(this.OR1.holds(this.cnfPredicate)).isTrue();
          assertThat(this.AND1.holds(this.cnfPredicate)).isTrue();
          assertThat(this.AND3.holds(this.cnfPredicate)).isTrue();
          assertThat(this.f.and(this.OR1, this.OR2, this.A, this.NY).holds(this.cnfPredicate)).isTrue();
          assertThat(this.PBC1.holds(this.cnfPredicate)).isFalse();
          assertThat(this.OR3.holds(this.cnfPredicate)).isFalse();
          assertThat(this.IMP1.holds(this.cnfPredicate)).isFalse();
          assertThat(this.EQ1.holds(this.cnfPredicate)).isFalse();
          assertThat(this.NOT1.holds(this.cnfPredicate)).isFalse();
          assertThat(this.NOT2.holds(this.cnfPredicate)).isFalse();
          assertThat(this.f.and(this.OR1, this.EQ1).holds(this.cnfPredicate)).isFalse();
      }
  
      @Test
      public void testIllegalAnd() {
          this.AND1.setPredicateCacheEntry(IS_CNF, null);
          assertThatThrownBy(() -> this.AND1.holds(this.cnfPredicate)).isInstanceOf(IllegalStateException.class);
      }
  
      @Test
      public void testToString() {
          assertThat(this.cnfPredicate.toString()).isEqualTo("CNFPredicate");
      }
  }
  