/*
    * 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
    *
    *      https://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.commons.lang3.compare;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertSame;
  
  import java.util.Arrays;
  import java.util.Comparator;
  import java.util.List;
  
  import org.apache.commons.lang3.AbstractLangTest;
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests {@link ObjectToStringComparator}.
   */
  class ObjectToStringComparatorTest extends AbstractLangTest {
  
      private static final class Thing {
  
          final String string;
  
          Thing(final String string) {
              this.string = string;
          }
  
          @Override
          public String toString() {
              return string;
          }
      }
  
      @Test
      void testCompareNulls() {
          final Comparator<Object> comp = ObjectToStringComparator.INSTANCE;
          assertEquals(0, comp.compare(null, null));
          final Object o1 = new Thing(null);
          final Object o2 = new Thing(null);
          assertEquals(0, comp.compare(o1, o1));
          assertEquals(0, comp.compare(o1, o2));
      }
  
      @Test
      void testCompareNullWithNonNull() {
          final Comparator<Object> comp = ObjectToStringComparator.INSTANCE;
          final Object o1 = new Thing(null);
          final Object o2 = new Thing("");
          assertEquals(0, comp.compare(o1, o1));
          assertEquals(0, comp.compare(o2, o2));
          assertEquals(1, comp.compare(o1, o2));
          assertEquals(-1, comp.compare(o2, o1));
          assertEquals(1, comp.compare(null, o2));
          assertEquals(-1, comp.compare(o2, null));
      }
  
      @Test
      void testNullLeft() {
          final Thing thing = new Thing("y");
          final List<Thing> things = Arrays.asList(null, thing);
          things.sort(ObjectToStringComparator.INSTANCE);
          assertEquals("y", things.get(0).string);
          assertEquals(2, things.size());
          assertSame(thing, things.get(0));
          assertNull(things.get(1));
      }
  
      @Test
      void testNullRight() {
          final Thing thing = new Thing("y");
          final List<Thing> things = Arrays.asList(thing, null);
          things.sort(ObjectToStringComparator.INSTANCE);
          assertEquals(2, things.size());
          assertSame(thing, things.get(0));
          assertNull(things.get(1));
      }
  
      @Test
      void testNulls() {
          final Thing thing = new Thing("y");
          final List<Thing> things = Arrays.asList(null, thing, null);
          things.sort(ObjectToStringComparator.INSTANCE);
          assertEquals("y", things.get(0).string);
         assertEquals(3, things.size());
         assertSame(thing, things.get(0));
         assertNull(things.get(1));
         assertNull(things.get(2));
     }
 
     @Test
     void testNullToString() {
         final List<Thing> things = Arrays.asList(new Thing(null), new Thing("y"), new Thing(null));
         things.sort(ObjectToStringComparator.INSTANCE);
         assertEquals("y", things.get(0).string);
         assertNull(things.get(1).string);
         assertNull(things.get(2).string);
     }
 
     @Test
     void testSortCollection() {
         final List<Thing> things = Arrays.asList(new Thing("z"), new Thing("y"), new Thing("x"));
         things.sort(ObjectToStringComparator.INSTANCE);
         assertEquals("x", things.get(0).string);
         assertEquals("y", things.get(1).string);
         assertEquals("z", things.get(2).string);
     }
 }