/*
    * Copyright (C) 2008 The Guava Authors
    *
    * 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 com.google.common.collect.testing.testers;
  
  import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.collect.testing.Helpers;
  import com.google.common.collect.testing.MinimalSet;
  import com.google.common.collect.testing.features.CollectionFeature;
  import com.google.common.collect.testing.features.CollectionSize;
  
  import java.util.Collection;
  import java.util.Set;
  
  /**
   * Tests {@link java.util.Set#equals}.
   *
   * @author George van den Driessche
   */
  @GwtCompatible
  public class SetEqualsTester<E> extends AbstractSetTester<E> {
    public void testEquals_otherSetWithSameElements() {
      assertTrue(
          "A Set should equal any other Set containing the same elements.",
          getSet().equals(MinimalSet.from(getSampleElements())));
    }
  
    @CollectionSize.Require(absent = CollectionSize.ZERO)
    public void testEquals_otherSetWithDifferentElements() {
      Collection<E> elements = getSampleElements(getNumElements() - 1);
      elements.add(getSubjectGenerator().samples().e3);
  
      assertFalse(
          "A Set should not equal another Set containing different elements.",
          getSet().equals(MinimalSet.from(elements))
      );
    }
  
    @CollectionSize.Require(absent = CollectionSize.ZERO)
    @CollectionFeature.Require(ALLOWS_NULL_VALUES)
    public void testEquals_containingNull() {
      Collection<E> elements = getSampleElements(getNumElements() - 1);
      elements.add(null);
  
      collection = getSubjectGenerator().create(elements.toArray());
      assertTrue("A Set should equal any other Set containing the same elements,"
          + " even if some elements are null.",
          getSet().equals(MinimalSet.from(elements)));
    }
  
    @CollectionSize.Require(absent = CollectionSize.ZERO)
    public void testEquals_otherContainsNull() {
      Collection<E> elements = getSampleElements(getNumElements() - 1);
      elements.add(null);
      Set<E> other = MinimalSet.from(elements);
  
      assertFalse(
          "Two Sets should not be equal if exactly one of them contains null.",
          getSet().equals(other));
    }
  
    @CollectionSize.Require(absent = CollectionSize.ZERO)
    public void testEquals_smallerSet() {
      Collection<E> fewerElements = getSampleElements(getNumElements() - 1);
      assertFalse("Sets of different sizes should not be equal.",
          getSet().equals(MinimalSet.from(fewerElements)));
    }
  
    public void testEquals_largerSet() {
      Collection<E> moreElements = getSampleElements(getNumElements() + 1);
      assertFalse("Sets of different sizes should not be equal.",
          getSet().equals(MinimalSet.from(moreElements)));
    }
  
    public void testEquals_list() {
      assertFalse("A List should never equal a Set.",
          getSet().equals(Helpers.copyToList(getSet())));
    }
  }