MapEqualsTester.java

/*
 * 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.MapFeature.ALLOWS_NULL_KEYS;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractMapTester;
import com.google.common.collect.testing.Helpers;
import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.MapFeature;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

/**
 * Tests {@link java.util.Map#equals}.
 *
 * <p>This class is GWT compatible.
 *
 * @author George van den Driessche
 * @author Chris Povirk
 */
@GwtCompatible
public class MapEqualsTester<K, V> extends AbstractMapTester<K, V> {
  public void testEquals_otherMapWithSameEntries() {
    assertTrue(
        "A Map should equal any other Map containing the same entries.",
        getMap().equals(newHashMap(getSampleEntries())));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherMapWithDifferentEntries() {
    Map<K, V> other = newHashMap(getSampleEntries(getNumEntries() - 1));
    Entry<K, V> e3 = getSubjectGenerator().samples().e3;
    other.put(e3.getKey(), e3.getValue());
    assertFalse(
        "A Map should not equal another Map containing different entries.",
        getMap().equals(other)
    );
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testEquals_containingNullKey() {
    Collection<Map.Entry<K, V>> entries = getSampleEntries(getNumEntries() - 1);
    entries.add(entry(null, samples.e3.getValue()));

    resetContainer(getSubjectGenerator().create(entries.toArray()));
    assertTrue("A Map should equal any other Map containing the same entries,"
        + " even if some keys are null.",
        getMap().equals(newHashMap(entries)));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherContainsNullKey() {
    Collection<Map.Entry<K, V>> entries = getSampleEntries(getNumEntries() - 1);
    entries.add(entry(null, samples.e3.getValue()));
    Map<K, V> other = newHashMap(entries);

    assertFalse(
        "Two Maps should not be equal if exactly one of them contains a null "
        + "key.",
        getMap().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  @MapFeature.Require(ALLOWS_NULL_VALUES)
  public void testEquals_containingNullValue() {
    Collection<Map.Entry<K, V>> entries = getSampleEntries(getNumEntries() - 1);
    entries.add(entry(samples.e3.getKey(), null));

    resetContainer(getSubjectGenerator().create(entries.toArray()));
    assertTrue("A Map should equal any other Map containing the same entries,"
        + " even if some values are null.",
        getMap().equals(newHashMap(entries)));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherContainsNullValue() {
    Collection<Map.Entry<K, V>> entries = getSampleEntries(getNumEntries() - 1);
    entries.add(entry(samples.e3.getKey(), null));
    Map<K, V> other = newHashMap(entries);

    assertFalse(
        "Two Maps should not be equal if exactly one of them contains a null "
        + "value.",
        getMap().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_smallerMap() {
    Collection<Map.Entry<K, V>> fewerEntries
        = getSampleEntries(getNumEntries() - 1);
    assertFalse("Maps of different sizes should not be equal.",
        getMap().equals(newHashMap(fewerEntries)));
  }

  public void testEquals_largerMap() {
    Collection<Map.Entry<K, V>> moreEntries
        = getSampleEntries(getNumEntries() + 1);
    assertFalse("Maps of different sizes should not be equal.",
        getMap().equals(newHashMap(moreEntries)));
  }

  public void testEquals_list() {
    assertFalse("A List should never equal a Map.",
        getMap().equals(Helpers.copyToList(getMap().entrySet())));
  }

  private static <K, V> HashMap<K, V> newHashMap(
      Collection<? extends Map.Entry<? extends K, ? extends V>> entries) {
    HashMap<K, V> map = new HashMap<K, V>();
    for (Map.Entry<? extends K, ? extends V> entry : entries) {
      map.put(entry.getKey(), entry.getValue());
    }
    return map;
  }
}