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.value;
  
  import java.util.List;
  
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.equalTo;
  import static org.hamcrest.Matchers.greaterThan;
  import static org.hamcrest.Matchers.is;
  import static org.hamcrest.Matchers.not;
  import static org.hamcrest.Matchers.notNullValue;
  import static org.junit.jupiter.api.Assumptions.assumeTrue;
  
  /**
   * Contract test for value types ({@link #equals(Object) equals} and
   * {@link #hashCode() hashCode}), and also {@link Comparable#compareTo(Object) compareTo} for
   * any value types that also are {@link Comparable}
   *
   * @since 2.0 {@index}
   */
  public abstract class ValueTypeContractTestAbstract<T> {
  
      @BeforeEach
      public void setUp() throws Exception {
          assertSizeAtLeast(getObjectsWithSameValue(), 2);
          assertSizeAtLeast(getObjectsWithDifferentValue(), 1);
      }
  
      private void assertSizeAtLeast(final List<T> objects, final int i) {
          assertThat(objects, is(notNullValue()));
          assertThat(objects.size(), is(greaterThan(i - 1)));
      }
  
      @Test
      public void notEqualToNull() throws Exception {
          for (final T o1 : getObjectsWithSameValue()) {
              assertThat(o1==null, is(false));
          }
          for (final T o1 : getObjectsWithDifferentValue()) {
              assertThat(o1==null, is(false));
          }
      }
  
      @Test
      public void reflexiveAndSymmetric() throws Exception {
          for (final T o1 : getObjectsWithSameValue()) {
              for (final T o2 : getObjectsWithSameValue()) {
                  assertThat(o1.equals(o2), is(true));
                  assertThat(o2.equals(o1), is(true));
                  assertThat(o1.hashCode(), is(equalTo(o2.hashCode())));
              }
          }
      }
  
      @Test
      public void notEqual() throws Exception {
          for (final T o1 : getObjectsWithSameValue()) {
              for (final T o2 : getObjectsWithDifferentValue()) {
                  assertThat(o1.equals(o2), is(false));
                  assertThat(o2.equals(o1), is(false));
              }
          }
      }
  
      @Test
      public void transitiveWhenEqual() throws Exception {
          for (final T o1 : getObjectsWithSameValue()) {
              for (final T o2 : getObjectsWithSameValue()) {
                  for (final Object o3 : getObjectsWithSameValue()) {
                      assertThat(o1.equals(o2), is(true));
                      assertThat(o2.equals(o3), is(true));
                      assertThat(o1.equals(o3), is(true));
                  }
              }
          }
      }
  
      @Test
      @SuppressWarnings({ "rawtypes", "unchecked" })
      public void comparableEquivalence() throws Exception {
          for (final T o1 : getObjectsWithSameValue()) {
              assumeTrue(o1 instanceof Comparable);
              Comparable c1 = (Comparable)o1;
  
              for (final T o2 : getObjectsWithSameValue()) {
                  assumeTrue(o2 instanceof Comparable);
                  Comparable c2 = (Comparable)o2;
  
                  assertThat(c1.compareTo(c2), is(0));
                  assertThat(c2.compareTo(c1), is(0));
              }
  
              for (final T o2 : getObjectsWithDifferentValue()) {
                  assumeTrue(o2 instanceof Comparable);
                  Comparable c2 = (Comparable)o2;
  
                  final int x = c1.compareTo(c2);
                  final int y = c2.compareTo(c1);
                  assertThat(x, is(not(0)));
  
                  assertThat(x, is(-y));
              }
          }
      }
  
      /**
       * Returns a list of different instances that are expected to have the same value (according to equals and hashCode).
       *
       * <p>
       *     At least two different instances must be provided.
       * </p>
       */
      protected abstract List<T> getObjectsWithSameValue();
  
      /**
       * Returns a list of instances that are different from each other and also from the instance(s) provided in the
       * {@link #getObjectsWithSameValue()} method.
       *
       * <p>
       *     It is often sufficient to provide a single instance (as it is compared against the instances provided by
       *     {@link #getObjectsWithSameValue()}).
       * </p>
       */
      protected abstract List<T> getObjectsWithDifferentValue();
  
  }
  