content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you 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.apache.causeway.testing.unittestsupport.applib.dom.comparable;
  
  import java.util.List;
  
  import org.hamcrest.Matchers;
  
  import static org.hamcrest.CoreMatchers.is;
  import static org.hamcrest.MatcherAssert.assertThat;
  
  import org.apache.causeway.commons.internal.collections._Lists;
  
  /**
   * @since 2.0 {@index}
   */
  public class ComparableContractTester<T extends Comparable<T>> {
  
      private final List<List<T>> orderedTuples;
  
      /**
       * Provide an array of tuples; each tuple should consist of 4 elements, whereby
       * item0  < item1 = item2 < item3
       *
       * Typically item0 should be null valued (if supported by the impl).
       */
      public ComparableContractTester(final List<List<T>> orderedTuples) {
          this.orderedTuples = orderedTuples;
      }
  
      public void test() {
  
          for(List<T> orderedTuple: orderedTuples) {
  
              T item1 = orderedTuple.get(0);
              T item2 = orderedTuple.get(1);
              T item3 = orderedTuple.get(2);
              T item4 = orderedTuple.get(3);
  
              assertThat(desc(item1, "<", item2), item1.compareTo(item2), is(Matchers.lessThan(0)));
              assertThat(desc(item2, ">", item1), item2.compareTo(item1), is(Matchers.greaterThan(0)));
  
              assertThat(desc(item2, "==", item3), item2.compareTo(item3), is(0));
              assertThat(desc(item3, "==", item2), item3.compareTo(item2), is(0));
  
              assertThat(desc(item3, "<", item4), item3.compareTo(item4), is(Matchers.lessThan(0)));
              assertThat(desc(item4, ">", item3), item4.compareTo(item3), is(Matchers.greaterThan(0)));
          }
      }
  
      protected static String desc(final Object item1, final String op, final Object item2) {
          return nullSafe(item1) + op + nullSafe(item2);
      }
  
      private static String nullSafe(final Object item) {
          return item != null? item.toString(): "null";
      }
  
      /**
       * Syntax sugar to remove boilerplate from subclasses.
       */
      @SafeVarargs
      public static <E> List<E> listOf(final E... elements) {
          return _Lists.ofArray(elements);
      }
  
  }
  