common/collect/MapsTest.java

/*
 * Copyright (C) 2007 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;

import static com.google.common.collect.Maps.transformEntries;
import static com.google.common.collect.Maps.transformValues;
import static com.google.common.collect.testing.Helpers.mapEntry;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Equivalence;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.Maps.EntryTransformer;
import com.google.common.collect.Maps.ValueDifferenceImpl;
import com.google.common.collect.SetsTest.Derived;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.NullPointerTester;

import junit.framework.TestCase;

import org.truth0.Truth;
import org.truth0.subjects.CollectionSubject;

import java.io.IOException;
import java.io.StringBufferInputStream;
import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.EnumMap;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentMap;

/**
 * Unit test for {@code Maps}.
 *
 * @author Kevin Bourrillion
 * @author Mike Bostock
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
public class MapsTest extends TestCase {

  private static final Comparator<Integer> SOME_COMPARATOR = Collections.reverseOrder();

  public void testHashMap() {
    HashMap<Integer, Integer> map = Maps.newHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testHashMapWithInitialMap() {
    Map<String, Integer> original = new TreeMap<String, Integer>();
    original.put("a", 1);
    original.put("b", 2);
    original.put("c", 3);
    HashMap<String, Integer> map = Maps.newHashMap(original);
    assertEquals(original, map);
  }

  public void testHashMapGeneralizesTypes() {
    Map<String, Integer> original = new TreeMap<String, Integer>();
    original.put("a", 1);
    original.put("b", 2);
    original.put("c", 3);
    HashMap<Object, Object> map = Maps
        .newHashMap((Map<? extends Object, ? extends Object>) original);
    assertEquals(original, map);
  }

  public void testCapacityForNegativeSizeFails() {
    try {
      Maps.capacity(-1);
      fail("Negative expected size must result in IllegalArgumentException");
    } catch (IllegalArgumentException ex) {}
  }

  /**
   * Tests that nHMWES makes hash maps large enough that adding the expected
   * number of elements won't cause a rehash.
   *
   * This test may fail miserably on non-OpenJDK environments...
   */
  @GwtIncompatible("reflection")
  public void notestNewHashMapWithExpectedSize_wontGrow() throws Exception {
    for (int size = 0; size < 200; size++) {
      HashMap<Integer, Void> map1 = Maps.newHashMapWithExpectedSize(size);

      int startSize = sizeOf(map1);

      for (int i = 0; i < size; i++) {
        map1.put(i, null);
      }
      assertEquals("table size after adding " + size + "elements", startSize, sizeOf(map1));

      /*
       * Something slightly different happens when the entries are added all at
       * once; make sure that passes too.
       */
      HashMap<Integer, Void> map2 = Maps.newHashMapWithExpectedSize(size);
      map2.putAll(map1);
      assertEquals("table size after adding " + size + "elements", startSize, sizeOf(map2));
    }
  }

  @GwtIncompatible("reflection")
  private static int sizeOf(HashMap<?, ?> hashMap) throws Exception {
    Field tableField = HashMap.class.getDeclaredField("table");
    tableField.setAccessible(true);
    Object[] table = (Object[]) tableField.get(hashMap);
    return table.length;
  }

  public void testCapacityForLargeSizes() {
    int[] largeExpectedSizes = new int[] { Integer.MAX_VALUE / 2 - 1, Integer.MAX_VALUE / 2,
        Integer.MAX_VALUE / 2 + 1, Integer.MAX_VALUE - 1, Integer.MAX_VALUE };
    for (int expectedSize : largeExpectedSizes) {
      int capacity = Maps.capacity(expectedSize);
      assertTrue("capacity (" + capacity + ") must be >= expectedSize (" + expectedSize + ")",
          capacity >= expectedSize);
    }
  }

  public void testLinkedHashMap() {
    LinkedHashMap<Integer, Integer> map = Maps.newLinkedHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  @SuppressWarnings("serial")
  public void testLinkedHashMapWithInitialMap() {
    Map<String, String> map = new LinkedHashMap<String, String>() {
      {
        put("Hello", "World");
        put("first", "second");
        put("polygene", "lubricants");
        put("alpha", "betical");
      }
    };

    LinkedHashMap<String, String> copy = Maps.newLinkedHashMap(map);

    Iterator<Entry<String, String>> iter = copy.entrySet().iterator();
    assertTrue(iter.hasNext());
    Entry<String, String> entry = iter.next();
    assertEquals("Hello", entry.getKey());
    assertEquals("World", entry.getValue());
    assertTrue(iter.hasNext());

    entry = iter.next();
    assertEquals("first", entry.getKey());
    assertEquals("second", entry.getValue());
    assertTrue(iter.hasNext());

    entry = iter.next();
    assertEquals("polygene", entry.getKey());
    assertEquals("lubricants", entry.getValue());
    assertTrue(iter.hasNext());

    entry = iter.next();
    assertEquals("alpha", entry.getKey());
    assertEquals("betical", entry.getValue());
    assertFalse(iter.hasNext());
  }

  public void testLinkedHashMapGeneralizesTypes() {
    Map<String, Integer> original = new LinkedHashMap<String, Integer>();
    original.put("a", 1);
    original.put("b", 2);
    original.put("c", 3);
    HashMap<Object, Object> map = Maps.<Object, Object>newLinkedHashMap(original);
    assertEquals(original, map);
  }

  public void testIdentityHashMap() {
    IdentityHashMap<Integer, Integer> map = Maps.newIdentityHashMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testConcurrentMap() {
    ConcurrentMap<Integer, Integer> map = Maps.newConcurrentMap();
    assertEquals(Collections.emptyMap(), map);
  }

  public void testTreeMap() {
    TreeMap<Integer, Integer> map = Maps.newTreeMap();
    assertEquals(Collections.emptyMap(), map);
    assertNull(map.comparator());
  }

  public void testTreeMapDerived() {
    TreeMap<Derived, Integer> map = Maps.newTreeMap();
    assertEquals(Collections.emptyMap(), map);
    map.put(new Derived("foo"), 1);
    map.put(new Derived("bar"), 2);
    ASSERT.that(map.keySet()).has().allOf(new Derived("bar"), new Derived("foo")).inOrder();
    ASSERT.that(map.values()).has().allOf(2, 1).inOrder();
    assertNull(map.comparator());
  }

  public void testTreeMapNonGeneric() {
    TreeMap<LegacyComparable, Integer> map = Maps.newTreeMap();
    assertEquals(Collections.emptyMap(), map);
    map.put(new LegacyComparable("foo"), 1);
    map.put(new LegacyComparable("bar"), 2);
    ASSERT.that(map.keySet()).has().allOf(new LegacyComparable("bar"), new LegacyComparable("foo"))
        .inOrder();
    ASSERT.that(map.values()).has().allOf(2, 1).inOrder();
    assertNull(map.comparator());
  }

  public void testTreeMapWithComparator() {
    TreeMap<Integer, Integer> map = Maps.<Integer, Integer, Integer>newTreeMap(SOME_COMPARATOR);
    assertEquals(Collections.emptyMap(), map);
    assertSame(SOME_COMPARATOR, map.comparator());
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);
    assertEquals(copy, map);
    assertSame(copy.comparator(), map.comparator());
  }

  public enum SomeEnum {
    SOME_INSTANCE
  }

  public void testEnumMap() {
    EnumMap<SomeEnum, Integer> map = Maps.newEnumMap(SomeEnum.class);
    assertEquals(Collections.emptyMap(), map);
    map.put(SomeEnum.SOME_INSTANCE, 0);
    assertEquals(Collections.singletonMap(SomeEnum.SOME_INSTANCE, 0), map);
  }

  public void testEnumMapNullClass() {
    try {
      Maps.<SomeEnum, Long>newEnumMap((Class<MapsTest.SomeEnum>) null);
      fail("no exception thrown");
    } catch (NullPointerException expected) {}
  }

  public void testEnumMapWithInitialEnumMap() {
    EnumMap<SomeEnum, Integer> original = Maps.newEnumMap(SomeEnum.class);
    original.put(SomeEnum.SOME_INSTANCE, 0);
    EnumMap<SomeEnum, Integer> copy = Maps.newEnumMap(original);
    assertEquals(original, copy);
  }

  public void testEnumMapWithInitialEmptyEnumMap() {
    EnumMap<SomeEnum, Integer> original = Maps.newEnumMap(SomeEnum.class);
    EnumMap<SomeEnum, Integer> copy = Maps.newEnumMap(original);
    assertEquals(original, copy);
    assertNotSame(original, copy);
  }

  public void testEnumMapWithInitialMap() {
    HashMap<SomeEnum, Integer> original = Maps.newHashMap();
    original.put(SomeEnum.SOME_INSTANCE, 0);
    EnumMap<SomeEnum, Integer> copy = Maps.newEnumMap(original);
    assertEquals(original, copy);
  }

  public void testEnumMapWithInitialEmptyMap() {
    Map<SomeEnum, Integer> original = Maps.newHashMap();
    try {
      Maps.newEnumMap(original);
      fail("Empty map must result in an IllegalArgumentException");
    } catch (IllegalArgumentException expected) {}
  }

  public void testToStringImplWithNullKeys() throws Exception {
    Map<String, String> hashmap = Maps.newHashMap();
    hashmap.put("foo", "bar");
    hashmap.put(null, "baz");

    assertEquals(hashmap.toString(), Maps.toStringImpl(hashmap));
  }

  public void testToStringImplWithNullValues() throws Exception {
    Map<String, String> hashmap = Maps.newHashMap();
    hashmap.put("foo", "bar");
    hashmap.put("baz", null);

    assertEquals(hashmap.toString(), Maps.toStringImpl(hashmap));
  }

  @GwtIncompatible("NullPointerTester")
  public void testNullPointerExceptions() {
    new NullPointerTester().testAllPublicStaticMethods(Maps.class);
  }

  private static final Map<Integer, Integer> EMPTY = Collections.emptyMap();
  private static final Map<Integer, Integer> SINGLETON = Collections.singletonMap(1, 2);

  public void testMapDifferenceEmptyEmpty() {
    MapDifference<Integer, Integer> diff = Maps.difference(EMPTY, EMPTY);
    assertTrue(diff.areEqual());
    assertEquals(EMPTY, diff.entriesOnlyOnLeft());
    assertEquals(EMPTY, diff.entriesOnlyOnRight());
    assertEquals(EMPTY, diff.entriesInCommon());
    assertEquals(EMPTY, diff.entriesDiffering());
    assertEquals("equal", diff.toString());
  }

  public void testMapDifferenceEmptySingleton() {
    MapDifference<Integer, Integer> diff = Maps.difference(EMPTY, SINGLETON);
    assertFalse(diff.areEqual());
    assertEquals(EMPTY, diff.entriesOnlyOnLeft());
    assertEquals(SINGLETON, diff.entriesOnlyOnRight());
    assertEquals(EMPTY, diff.entriesInCommon());
    assertEquals(EMPTY, diff.entriesDiffering());
    assertEquals("not equal: only on right={1=2}", diff.toString());
  }

  public void testMapDifferenceSingletonEmpty() {
    MapDifference<Integer, Integer> diff = Maps.difference(SINGLETON, EMPTY);
    assertFalse(diff.areEqual());
    assertEquals(SINGLETON, diff.entriesOnlyOnLeft());
    assertEquals(EMPTY, diff.entriesOnlyOnRight());
    assertEquals(EMPTY, diff.entriesInCommon());
    assertEquals(EMPTY, diff.entriesDiffering());
    assertEquals("not equal: only on left={1=2}", diff.toString());
  }

  public void testMapDifferenceTypical() {
    Map<Integer, String> left = ImmutableMap.of(1, "a", 2, "b", 3, "c", 4, "d", 5, "e");
    Map<Integer, String> right = ImmutableMap.of(1, "a", 3, "f", 5, "g", 6, "z");

    MapDifference<Integer, String> diff1 = Maps.difference(left, right);
    assertFalse(diff1.areEqual());
    assertEquals(ImmutableMap.of(2, "b", 4, "d"), diff1.entriesOnlyOnLeft());
    assertEquals(ImmutableMap.of(6, "z"), diff1.entriesOnlyOnRight());
    assertEquals(ImmutableMap.of(1, "a"), diff1.entriesInCommon());
    assertEquals(
        ImmutableMap.of(3, ValueDifferenceImpl.create("c", "f"), 5,
            ValueDifferenceImpl.create("e", "g")), diff1.entriesDiffering());
    assertEquals("not equal: only on left={2=b, 4=d}: only on right={6=z}: "
        + "value differences={3=(c, f), 5=(e, g)}", diff1.toString());

    MapDifference<Integer, String> diff2 = Maps.difference(right, left);
    assertFalse(diff2.areEqual());
    assertEquals(ImmutableMap.of(6, "z"), diff2.entriesOnlyOnLeft());
    assertEquals(ImmutableMap.of(2, "b", 4, "d"), diff2.entriesOnlyOnRight());
    assertEquals(ImmutableMap.of(1, "a"), diff2.entriesInCommon());
    assertEquals(
        ImmutableMap.of(3, ValueDifferenceImpl.create("f", "c"), 5,
            ValueDifferenceImpl.create("g", "e")), diff2.entriesDiffering());
    assertEquals("not equal: only on left={6=z}: only on right={2=b, 4=d}: "
        + "value differences={3=(f, c), 5=(g, e)}", diff2.toString());
  }

  public void testMapDifferenceEquals() {
    Map<Integer, String> left = ImmutableMap.of(1, "a", 2, "b", 3, "c", 4, "d", 5, "e");
    Map<Integer, String> right = ImmutableMap.of(1, "a", 3, "f", 5, "g", 6, "z");
    Map<Integer, String> right2 = ImmutableMap.of(1, "a", 3, "h", 5, "g", 6, "z");
    MapDifference<Integer, String> original = Maps.difference(left, right);
    MapDifference<Integer, String> same = Maps.difference(left, right);
    MapDifference<Integer, String> reverse = Maps.difference(right, left);
    MapDifference<Integer, String> diff2 = Maps.difference(left, right2);

    new EqualsTester().addEqualityGroup(original, same).addEqualityGroup(reverse)
        .addEqualityGroup(diff2).testEquals();
  }

  public void testMapDifferencePredicateTypical() {
    Map<Integer, String> left = ImmutableMap.of(1, "a", 2, "b", 3, "c", 4, "d", 5, "e");
    Map<Integer, String> right = ImmutableMap.of(1, "A", 3, "F", 5, "G", 6, "Z");

    // TODO(kevinb): replace with Ascii.caseInsensitiveEquivalence() when it
    // exists
    Equivalence<String> caseInsensitiveEquivalence = Equivalence.equals().onResultOf(
        new Function<String, String>() {
          @Override
          public String apply(String input) {
            return input.toLowerCase();
          }
        });

    MapDifference<Integer, String> diff1 = Maps.difference(left, right, caseInsensitiveEquivalence);
    assertFalse(diff1.areEqual());
    assertEquals(ImmutableMap.of(2, "b", 4, "d"), diff1.entriesOnlyOnLeft());
    assertEquals(ImmutableMap.of(6, "Z"), diff1.entriesOnlyOnRight());
    assertEquals(ImmutableMap.of(1, "a"), diff1.entriesInCommon());
    assertEquals(
        ImmutableMap.of(3, ValueDifferenceImpl.create("c", "F"), 5,
            ValueDifferenceImpl.create("e", "G")), diff1.entriesDiffering());
    assertEquals("not equal: only on left={2=b, 4=d}: only on right={6=Z}: "
        + "value differences={3=(c, F), 5=(e, G)}", diff1.toString());

    MapDifference<Integer, String> diff2 = Maps.difference(right, left, caseInsensitiveEquivalence);
    assertFalse(diff2.areEqual());
    assertEquals(ImmutableMap.of(6, "Z"), diff2.entriesOnlyOnLeft());
    assertEquals(ImmutableMap.of(2, "b", 4, "d"), diff2.entriesOnlyOnRight());
    assertEquals(ImmutableMap.of(1, "A"), diff2.entriesInCommon());
    assertEquals(
        ImmutableMap.of(3, ValueDifferenceImpl.create("F", "c"), 5,
            ValueDifferenceImpl.create("G", "e")), diff2.entriesDiffering());
    assertEquals("not equal: only on left={6=Z}: only on right={2=b, 4=d}: "
        + "value differences={3=(F, c), 5=(G, e)}", diff2.toString());
  }

  private static final SortedMap<Integer, Integer> SORTED_EMPTY = Maps.newTreeMap();
  private static final SortedMap<Integer, Integer> SORTED_SINGLETON = ImmutableSortedMap.of(1, 2);

  public void testMapDifferenceOfSortedMapIsSorted() {
    Map<Integer, Integer> map = SORTED_SINGLETON;
    MapDifference<Integer, Integer> difference = Maps.difference(map, EMPTY);
    assertTrue(difference instanceof SortedMapDifference);
  }

  public void testSortedMapDifferenceEmptyEmpty() {
    SortedMapDifference<Integer, Integer> diff = Maps.difference(SORTED_EMPTY, SORTED_EMPTY);
    assertTrue(diff.areEqual());
    assertEquals(SORTED_EMPTY, diff.entriesOnlyOnLeft());
    assertEquals(SORTED_EMPTY, diff.entriesOnlyOnRight());
    assertEquals(SORTED_EMPTY, diff.entriesInCommon());
    assertEquals(SORTED_EMPTY, diff.entriesDiffering());
    assertEquals("equal", diff.toString());
  }

  public void testSortedMapDifferenceEmptySingleton() {
    SortedMapDifference<Integer, Integer> diff = Maps.difference(SORTED_EMPTY, SORTED_SINGLETON);
    assertFalse(diff.areEqual());
    assertEquals(SORTED_EMPTY, diff.entriesOnlyOnLeft());
    assertEquals(SORTED_SINGLETON, diff.entriesOnlyOnRight());
    assertEquals(SORTED_EMPTY, diff.entriesInCommon());
    assertEquals(SORTED_EMPTY, diff.entriesDiffering());
    assertEquals("not equal: only on right={1=2}", diff.toString());
  }

  public void testSortedMapDifferenceSingletonEmpty() {
    SortedMapDifference<Integer, Integer> diff = Maps.difference(SORTED_SINGLETON, SORTED_EMPTY);
    assertFalse(diff.areEqual());
    assertEquals(SORTED_SINGLETON, diff.entriesOnlyOnLeft());
    assertEquals(SORTED_EMPTY, diff.entriesOnlyOnRight());
    assertEquals(SORTED_EMPTY, diff.entriesInCommon());
    assertEquals(SORTED_EMPTY, diff.entriesDiffering());
    assertEquals("not equal: only on left={1=2}", diff.toString());
  }

  public void testSortedMapDifferenceTypical() {
    SortedMap<Integer, String> left = ImmutableSortedMap.<Integer, String>reverseOrder()
        .put(1, "a").put(2, "b").put(3, "c").put(4, "d").put(5, "e").build();

    SortedMap<Integer, String> right = ImmutableSortedMap.of(1, "a", 3, "f", 5, "g", 6, "z");

    SortedMapDifference<Integer, String> diff1 = Maps.difference(left, right);
    assertFalse(diff1.areEqual());
    ASSERT.that(diff1.entriesOnlyOnLeft().entrySet()).has()
        .allOf(Maps.immutableEntry(4, "d"), Maps.immutableEntry(2, "b")).inOrder();
    ASSERT.that(diff1.entriesOnlyOnRight().entrySet()).has().item(Maps.immutableEntry(6, "z"));
    ASSERT.that(diff1.entriesInCommon().entrySet()).has().item(Maps.immutableEntry(1, "a"));
    ASSERT.that(diff1.entriesDiffering().entrySet())
        .has()
        .allOf(Maps.immutableEntry(5, ValueDifferenceImpl.create("e", "g")),
            Maps.immutableEntry(3, ValueDifferenceImpl.create("c", "f"))).inOrder();
    assertEquals("not equal: only on left={4=d, 2=b}: only on right={6=z}: "
        + "value differences={5=(e, g), 3=(c, f)}", diff1.toString());

    SortedMapDifference<Integer, String> diff2 = Maps.difference(right, left);
    assertFalse(diff2.areEqual());
    ASSERT.that(diff2.entriesOnlyOnLeft().entrySet()).has().item(Maps.immutableEntry(6, "z"));
    ASSERT.that(diff2.entriesOnlyOnRight().entrySet()).has()
        .allOf(Maps.immutableEntry(2, "b"), Maps.immutableEntry(4, "d")).inOrder();
    ASSERT.that(diff1.entriesInCommon().entrySet()).has().item(Maps.immutableEntry(1, "a"));
    assertEquals(
        ImmutableMap.of(3, ValueDifferenceImpl.create("f", "c"), 5,
            ValueDifferenceImpl.create("g", "e")), diff2.entriesDiffering());
    assertEquals("not equal: only on left={6=z}: only on right={2=b, 4=d}: "
        + "value differences={3=(f, c), 5=(g, e)}", diff2.toString());
  }

  public void testSortedMapDifferenceImmutable() {
    SortedMap<Integer, String> left = Maps.newTreeMap(ImmutableSortedMap.of(1, "a", 2, "b", 3, "c",
        4, "d", 5, "e"));
    SortedMap<Integer, String> right = Maps.newTreeMap(ImmutableSortedMap.of(1, "a", 3, "f", 5,
        "g", 6, "z"));

    SortedMapDifference<Integer, String> diff1 = Maps.difference(left, right);
    left.put(6, "z");
    assertFalse(diff1.areEqual());
    ASSERT.that(diff1.entriesOnlyOnLeft().entrySet()).has()
        .allOf(Maps.immutableEntry(2, "b"), Maps.immutableEntry(4, "d")).inOrder();
    ASSERT.that(diff1.entriesOnlyOnRight().entrySet()).has().item(Maps.immutableEntry(6, "z"));
    ASSERT.that(diff1.entriesInCommon().entrySet()).has().item(Maps.immutableEntry(1, "a"));
    ASSERT.that(diff1.entriesDiffering().entrySet())
        .has()
        .allOf(Maps.immutableEntry(3, ValueDifferenceImpl.create("c", "f")),
            Maps.immutableEntry(5, ValueDifferenceImpl.create("e", "g"))).inOrder();
    try {
      diff1.entriesInCommon().put(7, "x");
      fail();
    } catch (UnsupportedOperationException expected) {}
    try {
      diff1.entriesOnlyOnLeft().put(7, "x");
      fail();
    } catch (UnsupportedOperationException expected) {}
    try {
      diff1.entriesOnlyOnRight().put(7, "x");
      fail();
    } catch (UnsupportedOperationException expected) {}
  }

  public void testSortedMapDifferenceEquals() {
    SortedMap<Integer, String> left = ImmutableSortedMap.of(1, "a", 2, "b", 3, "c", 4, "d", 5, "e");
    SortedMap<Integer, String> right = ImmutableSortedMap.of(1, "a", 3, "f", 5, "g", 6, "z");
    SortedMap<Integer, String> right2 = ImmutableSortedMap.of(1, "a", 3, "h", 5, "g", 6, "z");
    SortedMapDifference<Integer, String> original = Maps.difference(left, right);
    SortedMapDifference<Integer, String> same = Maps.difference(left, right);
    SortedMapDifference<Integer, String> reverse = Maps.difference(right, left);
    SortedMapDifference<Integer, String> diff2 = Maps.difference(left, right2);

    new EqualsTester().addEqualityGroup(original, same).addEqualityGroup(reverse)
        .addEqualityGroup(diff2).testEquals();
  }

  private static final Function<String, Integer> LENGTH_FUNCTION = new Function<String, Integer>() {
    @Override
    public Integer apply(String input) {
      return input.length();
    }
  };

  public void testAsMap() {
    Set<String> strings = ImmutableSet.of("one", "two", "three");
    Map<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    assertEquals(Integer.valueOf(5), map.get("three"));
    assertNull(map.get("five"));
    ASSERT.that(map.entrySet()).has()
        .allOf(mapEntry("one", 3), mapEntry("two", 3), mapEntry("three", 5)).inOrder();
  }

  public void testAsMapReadsThrough() {
    Set<String> strings = Sets.newLinkedHashSet();
    Collections.addAll(strings, "one", "two", "three");
    Map<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    assertNull(map.get("four"));
    strings.add("four");
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5, "four", 4), map);
    assertEquals(Integer.valueOf(4), map.get("four"));
  }

  public void testAsMapWritesThrough() {
    Set<String> strings = Sets.newLinkedHashSet();
    Collections.addAll(strings, "one", "two", "three");
    Map<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    assertEquals(Integer.valueOf(3), map.remove("two"));
    ASSERT.that(strings).has().allOf("one", "three").inOrder();
  }

  public void testAsMapEmpty() {
    Set<String> strings = ImmutableSet.of();
    Map<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    ASSERT.that(map.entrySet()).isEmpty();
    assertTrue(map.isEmpty());
    assertNull(map.get("five"));
  }

  private static class NonNavigableSortedSet extends ForwardingSortedSet<String> {
    private final SortedSet<String> delegate = Sets.newTreeSet();

    @Override
    protected SortedSet<String> delegate() {
      return delegate;
    }
  }

  public void testAsMapReturnsSortedMapForSortedSetInput() {
    Set<String> set = new NonNavigableSortedSet();
    assertTrue(Maps.asMap(set, Functions.identity()) instanceof SortedMap);
  }

  public void testAsMapSorted() {
    SortedSet<String> strings = new NonNavigableSortedSet();
    Collections.addAll(strings, "one", "two", "three");
    SortedMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    assertEquals(Integer.valueOf(5), map.get("three"));
    assertNull(map.get("five"));
    ASSERT.that(map.entrySet()).has()
        .allOf(mapEntry("one", 3), mapEntry("three", 5), mapEntry("two", 3)).inOrder();
    ASSERT.that(map.tailMap("onea").entrySet()).has()
        .allOf(mapEntry("three", 5), mapEntry("two", 3)).inOrder();
    ASSERT.that(map.subMap("one", "two").entrySet()).has()
        .allOf(mapEntry("one", 3), mapEntry("three", 5)).inOrder();
  }

  public void testAsMapSortedReadsThrough() {
    SortedSet<String> strings = new NonNavigableSortedSet();
    Collections.addAll(strings, "one", "two", "three");
    SortedMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertNull(map.comparator());
    assertEquals(ImmutableSortedMap.of("one", 3, "two", 3, "three", 5), map);
    assertNull(map.get("four"));
    strings.add("four");
    assertEquals(ImmutableSortedMap.of("one", 3, "two", 3, "three", 5, "four", 4), map);
    assertEquals(Integer.valueOf(4), map.get("four"));
    SortedMap<String, Integer> headMap = map.headMap("two");
    assertEquals(ImmutableSortedMap.of("four", 4, "one", 3, "three", 5), headMap);
    strings.add("five");
    strings.remove("one");
    assertEquals(ImmutableSortedMap.of("five", 4, "four", 4, "three", 5), headMap);
    ASSERT.that(map.entrySet()).has()
        .allOf(mapEntry("five", 4), mapEntry("four", 4), mapEntry("three", 5), mapEntry("two", 3))
        .inOrder();
  }

  public void testAsMapSortedWritesThrough() {
    SortedSet<String> strings = new NonNavigableSortedSet();
    Collections.addAll(strings, "one", "two", "three");
    SortedMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    assertEquals(Integer.valueOf(3), map.remove("two"));
    ASSERT.that(strings).has().allOf("one", "three").inOrder();
  }

  public void testAsMapSortedSubViewKeySetsDoNotSupportAdd() {
    SortedMap<String, Integer> map = Maps.asMap(new NonNavigableSortedSet(), LENGTH_FUNCTION);
    try {
      map.subMap("a", "z").keySet().add("a");
      fail();
    } catch (UnsupportedOperationException expected) {}
    try {
      map.tailMap("a").keySet().add("a");
      fail();
    } catch (UnsupportedOperationException expected) {}
    try {
      map.headMap("r").keySet().add("a");
      fail();
    } catch (UnsupportedOperationException expected) {}
    try {
      map.headMap("r").tailMap("m").keySet().add("a");
      fail();
    } catch (UnsupportedOperationException expected) {}
  }

  public void testAsMapSortedEmpty() {
    SortedSet<String> strings = new NonNavigableSortedSet();
    SortedMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    ASSERT.that(map.entrySet()).isEmpty();
    assertTrue(map.isEmpty());
    assertNull(map.get("five"));
  }

  public void testToMap() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    ImmutableMap<String, Integer> map = Maps.toMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    ASSERT.that(map.entrySet()).has()
        .allOf(mapEntry("one", 3), mapEntry("two", 3), mapEntry("three", 5)).inOrder();
  }

  public void testToMapIterator() {
    Iterator<String> strings = ImmutableList.of("one", "two", "three").iterator();
    ImmutableMap<String, Integer> map = Maps.toMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    ASSERT.that(map.entrySet()).has()
        .allOf(mapEntry("one", 3), mapEntry("two", 3), mapEntry("three", 5)).inOrder();
  }

  public void testToMapWithDuplicateKeys() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three", "two", "one");
    ImmutableMap<String, Integer> map = Maps.toMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);
    ASSERT.that(map.entrySet()).has()
        .allOf(mapEntry("one", 3), mapEntry("two", 3), mapEntry("three", 5)).inOrder();
  }

  public void testToMapWithNullKeys() {
    Iterable<String> strings = Arrays.asList("one", null, "three");
    try {
      Maps.toMap(strings, Functions.constant("foo"));
      fail();
    } catch (NullPointerException expected) {}
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    try {
      Maps.toMap(strings, Functions.constant(null));
      fail();
    } catch (NullPointerException expected) {}
  }

  private static final BiMap<Integer, String> INT_TO_STRING_MAP = new ImmutableBiMap.Builder<Integer, String>()
      .put(1, "one").put(2, "two").put(3, "three").build();

  public void testUniqueIndexCollection() {
    ImmutableMap<Integer, String> outputMap = Maps.uniqueIndex(INT_TO_STRING_MAP.values(),
        Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  public void testUniqueIndexIterable() {
    ImmutableMap<Integer, String> outputMap = Maps.uniqueIndex(new Iterable<String>() {
      @Override
      public Iterator<String> iterator() {
        return INT_TO_STRING_MAP.values().iterator();
      }
    }, Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  public void testUniqueIndexIterator() {
    ImmutableMap<Integer, String> outputMap = Maps.uniqueIndex(INT_TO_STRING_MAP.values()
        .iterator(), Functions.forMap(INT_TO_STRING_MAP.inverse()));
    assertEquals(INT_TO_STRING_MAP, outputMap);
  }

  /** Can't create the map if more than one value maps to the same key. */
  public void testUniqueIndexDuplicates() {
    try {
      Maps.uniqueIndex(ImmutableSet.of("one", "uno"), Functions.constant(1));
      fail();
    } catch (IllegalArgumentException expected) {}
  }

  /** Null values are not allowed. */
  public void testUniqueIndexNullValue() {
    List<String> listWithNull = Lists.newArrayList((String) null);
    try {
      Maps.uniqueIndex(listWithNull, Functions.constant(1));
      fail();
    } catch (NullPointerException expected) {}
  }

  /** Null keys aren't allowed either. */
  public void testUniqueIndexNullKey() {
    List<String> oneStringList = Lists.newArrayList("foo");
    try {
      Maps.uniqueIndex(oneStringList, Functions.constant(null));
      fail();
    } catch (NullPointerException expected) {}
  }

  @GwtIncompatible("Maps.fromProperties")
  @SuppressWarnings("deprecation")
  // StringBufferInputStream
  public void testFromProperties() throws IOException {
    Properties testProp = new Properties();

    Map<String, String> result = Maps.fromProperties(testProp);
    assertTrue(result.isEmpty());
    testProp.setProperty("first", "true");

    result = Maps.fromProperties(testProp);
    assertEquals("true", result.get("first"));
    assertEquals(1, result.size());
    testProp.setProperty("second", "null");

    result = Maps.fromProperties(testProp);
    assertEquals("true", result.get("first"));
    assertEquals("null", result.get("second"));
    assertEquals(2, result.size());

    // Now test values loaded from a stream.
    String props = "test\n second = 2\n Third item :   a short  phrase   ";

    testProp.load(new StringBufferInputStream(props));

    result = Maps.fromProperties(testProp);
    assertEquals(4, result.size());
    assertEquals("true", result.get("first"));
    assertEquals("", result.get("test"));
    assertEquals("2", result.get("second"));
    assertEquals("item :   a short  phrase   ", result.get("Third"));
    assertFalse(result.containsKey("not here"));

    // Test loading system properties
    result = Maps.fromProperties(System.getProperties());
    assertTrue(result.containsKey("java.version"));

    // Test that defaults work, too.
    testProp = new Properties(System.getProperties());
    String override = "test\njava.version : hidden";

    testProp.load(new StringBufferInputStream(override));

    result = Maps.fromProperties(testProp);
    assertTrue(result.size() > 2);
    assertEquals("", result.get("test"));
    assertEquals("hidden", result.get("java.version"));
    assertNotSame(System.getProperty("java.version"), result.get("java.version"));
  }

  @GwtIncompatible("Maps.fromProperties")
  @SuppressWarnings("serial")
  // never serialized
  public void testFromPropertiesNullKey() {
    Properties properties = new Properties() {
      @Override
      public Enumeration<?> propertyNames() {
        return Iterators.asEnumeration(Arrays.asList(null, "first", "second").iterator());
      }
    };
    properties.setProperty("first", "true");
    properties.setProperty("second", "null");

    try {
      Maps.fromProperties(properties);
      fail();
    } catch (NullPointerException expected) {}
  }

  @GwtIncompatible("Maps.fromProperties")
  @SuppressWarnings("serial")
  // never serialized
  public void testFromPropertiesNonStringKeys() {
    Properties properties = new Properties() {
      @Override
      public Enumeration<?> propertyNames() {
        return Iterators.asEnumeration(Arrays.<Object>asList(Integer.valueOf(123), "first")
            .iterator());
      }
    };

    try {
      Maps.fromProperties(properties);
      fail();
    } catch (ClassCastException expected) {}
  }

  /**
   * Constructs a "nefarious" map entry with the specified key and value,
   * meaning an entry that is suitable for testing that map entries cannot be
   * modified via a nefarious implementation of equals. This is used for testing
   * unmodifiable collections of map entries; for example, it should not be
   * possible to access the raw (modifiable) map entry via a nefarious equals
   * method.
   */
  public static <K, V> Map.Entry<K, V> nefariousEntry(final K key, final V value) {
    return new AbstractMapEntry<K, V>() {
      @Override
      public K getKey() {
        return key;
      }

      @Override
      public V getValue() {
        return value;
      }

      @Override
      public V setValue(V value) {
        throw new UnsupportedOperationException();
      }

      @SuppressWarnings("unchecked")
      @Override
      public boolean equals(Object o) {
        if (o instanceof Map.Entry) {
          Map.Entry<K, V> e = (Map.Entry<K, V>) o;
          e.setValue(value); // muhahaha!
        }
        return super.equals(o);
      }
    };
  }

  public void testUnmodifiableBiMap() {
    BiMap<Integer, String> mod = HashBiMap.create();
    mod.put(1, "one");
    mod.put(2, "two");
    mod.put(3, "three");

    BiMap<Number, String> unmod = Maps.<Number, String>unmodifiableBiMap(mod);

    /* No aliasing on inverse operations. */
    assertSame(unmod.inverse(), unmod.inverse());
    assertSame(unmod, unmod.inverse().inverse());

    /* Unmodifiable is a view. */
    mod.put(4, "four");
    assertEquals(true, unmod.get(4).equals("four"));
    assertEquals(true, unmod.inverse().get("four").equals(4));

    /* UnsupportedOperationException on direct modifications. */
    try {
      unmod.put(4, "four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    try {
      unmod.forcePut(4, "four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    try {
      unmod.putAll(Collections.singletonMap(4, "four"));
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}

    /* UnsupportedOperationException on indirect modifications. */
    BiMap<String, Number> inverse = unmod.inverse();
    try {
      inverse.put("four", 4);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    try {
      inverse.forcePut("four", 4);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    try {
      inverse.putAll(Collections.singletonMap("four", 4));
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    Set<String> values = unmod.values();
    try {
      values.remove("four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    Set<Map.Entry<Number, String>> entries = unmod.entrySet();
    Map.Entry<Number, String> entry = entries.iterator().next();
    try {
      entry.setValue("four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    @SuppressWarnings("unchecked")
    Map.Entry<Integer, String> entry2 = (Map.Entry<Integer, String>) entries.toArray()[0];
    try {
      entry2.setValue("four");
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
  }

  public void testImmutableEntry() {
    Map.Entry<String, Integer> e = Maps.immutableEntry("foo", 1);
    assertEquals("foo", e.getKey());
    assertEquals(1, (int) e.getValue());
    try {
      e.setValue(2);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    assertEquals("foo=1", e.toString());
    assertEquals(101575, e.hashCode());
  }

  public void testImmutableEntryNull() {
    Map.Entry<String, Integer> e = Maps.immutableEntry((String) null, (Integer) null);
    assertNull(e.getKey());
    assertNull(e.getValue());
    try {
      e.setValue(null);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {}
    assertEquals("null=null", e.toString());
    assertEquals(0, e.hashCode());
  }

  /** See {@link SynchronizedBiMapTest} for more tests. */
  public void testSynchronizedBiMap() {
    BiMap<String, Integer> bimap = HashBiMap.create();
    bimap.put("one", 1);
    BiMap<String, Integer> sync = Maps.synchronizedBiMap(bimap);
    bimap.put("two", 2);
    sync.put("three", 3);
    assertEquals(ImmutableSet.of(1, 2, 3), bimap.inverse().keySet());
    assertEquals(ImmutableSet.of(1, 2, 3), sync.inverse().keySet());
  }

  private static final Predicate<String> NOT_LENGTH_3 = new Predicate<String>() {
    @Override
    public boolean apply(String input) {
      return input == null || input.length() != 3;
    }
  };

  private static final Predicate<Integer> EVEN = new Predicate<Integer>() {
    @Override
    public boolean apply(Integer input) {
      return input == null || input % 2 == 0;
    }
  };

  private static final Predicate<Entry<String, Integer>> CORRECT_LENGTH = new Predicate<Entry<String, Integer>>() {
    @Override
    public boolean apply(Entry<String, Integer> input) {
      return input.getKey().length() == input.getValue();
    }
  };

  private static final Function<Integer, Double> SQRT_FUNCTION = new Function<Integer, Double>() {
    @Override
    public Double apply(Integer in) {
      return Math.sqrt(in);
    }
  };

  public static class FilteredMapTest extends TestCase {
    Map<String, Integer> createUnfiltered() {
      return Maps.newHashMap();
    }

    public void testFilteredKeysIllegalPut() {
      Map<String, Integer> unfiltered = createUnfiltered();
      Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
      filtered.put("a", 1);
      filtered.put("b", 2);
      assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

      try {
        filtered.put("yyy", 3);
        fail();
      } catch (IllegalArgumentException expected) {}
    }

    public void testFilteredKeysIllegalPutAll() {
      Map<String, Integer> unfiltered = createUnfiltered();
      Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
      filtered.put("a", 1);
      filtered.put("b", 2);
      assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);

      try {
        filtered.putAll(ImmutableMap.of("c", 3, "zzz", 4, "b", 5));
        fail();
      } catch (IllegalArgumentException expected) {}

      assertEquals(ImmutableMap.of("a", 1, "b", 2), filtered);
    }

    public void testFilteredKeysFilteredReflectsBackingChanges() {
      Map<String, Integer> unfiltered = createUnfiltered();
      Map<String, Integer> filtered = Maps.filterKeys(unfiltered, NOT_LENGTH_3);
      unfiltered.put("two", 2);
      unfiltered.put("three", 3);
      unfiltered.put("four", 4);
      assertEquals(ImmutableMap.of("two", 2, "three", 3, "four", 4), unfiltered);
      assertEquals(ImmutableMap.of("three", 3, "four", 4), filtered);

      unfiltered.remove("three");
      assertEquals(ImmutableMap.of("two", 2, "four", 4), unfiltered);
      assertEquals(ImmutableMap.of("four", 4), filtered);

      unfiltered.clear();
      assertEquals(ImmutableMap.of(), unfiltered);
      assertEquals(ImmutableMap.of(), filtered);
    }

    public void testFilteredValuesIllegalPut() {
      Map<String, Integer> unfiltered = createUnfiltered();
      Map<String, Integer> filtered = Maps.filterValues(unfiltered, EVEN);
      filtered.put("a", 2);
      unfiltered.put("b", 4);
      unfiltered.put("c", 5);
      assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);

      try {
        filtered.put("yyy", 3);
        fail();
      } catch (IllegalArgumentException expected) {}
      assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);
    }

    public void testFilteredValuesIllegalPutAll() {
      Map<String, Integer> unfiltered = createUnfiltered();
      Map<String, Integer> filtered = Maps.filterValues(unfiltered, EVEN);
      filtered.put("a", 2);
      unfiltered.put("b", 4);
      unfiltered.put("c", 5);
      assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);

      try {
        filtered.putAll(ImmutableMap.of("c", 4, "zzz", 5, "b", 6));
        fail();
      } catch (IllegalArgumentException expected) {}
      assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);
    }

    public void testFilteredValuesIllegalSetValue() {
      Map<String, Integer> unfiltered = createUnfiltered();
      Map<String, Integer> filtered = Maps.filterValues(unfiltered, EVEN);
      filtered.put("a", 2);
      filtered.put("b", 4);
      assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);

      Entry<String, Integer> entry = filtered.entrySet().iterator().next();
      try {
        entry.setValue(5);
        fail();
      } catch (IllegalArgumentException expected) {}

      assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);
    }

    public void testFilteredValuesClear() {
      Map<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("one", 1);
      unfiltered.put("two", 2);
      unfiltered.put("three", 3);
      unfiltered.put("four", 4);
      Map<String, Integer> filtered = Maps.filterValues(unfiltered, EVEN);
      assertEquals(ImmutableMap.of("one", 1, "two", 2, "three", 3, "four", 4), unfiltered);
      assertEquals(ImmutableMap.of("two", 2, "four", 4), filtered);

      filtered.clear();
      assertEquals(ImmutableMap.of("one", 1, "three", 3), unfiltered);
      assertTrue(filtered.isEmpty());
    }

    public void testFilteredEntriesIllegalPut() {
      Map<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("cat", 3);
      unfiltered.put("dog", 2);
      unfiltered.put("horse", 5);
      Map<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);
      assertEquals(ImmutableMap.of("cat", 3, "horse", 5), filtered);

      filtered.put("chicken", 7);
      assertEquals(ImmutableMap.of("cat", 3, "horse", 5, "chicken", 7), filtered);

      try {
        filtered.put("cow", 7);
        fail();
      } catch (IllegalArgumentException expected) {}
      assertEquals(ImmutableMap.of("cat", 3, "horse", 5, "chicken", 7), filtered);
    }

    public void testFilteredEntriesIllegalPutAll() {
      Map<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("cat", 3);
      unfiltered.put("dog", 2);
      unfiltered.put("horse", 5);
      Map<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);
      assertEquals(ImmutableMap.of("cat", 3, "horse", 5), filtered);

      filtered.put("chicken", 7);
      assertEquals(ImmutableMap.of("cat", 3, "horse", 5, "chicken", 7), filtered);

      try {
        filtered.putAll(ImmutableMap.of("sheep", 5, "cow", 7));
        fail();
      } catch (IllegalArgumentException expected) {}
      assertEquals(ImmutableMap.of("cat", 3, "horse", 5, "chicken", 7), filtered);
    }

    public void testFilteredEntriesObjectPredicate() {
      Map<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("cat", 3);
      unfiltered.put("dog", 2);
      unfiltered.put("horse", 5);
      Predicate<Object> predicate = Predicates.alwaysFalse();
      Map<String, Integer> filtered = Maps.filterEntries(unfiltered, predicate);
      assertTrue(filtered.isEmpty());
    }

    public void testFilteredEntriesWildCardEntryPredicate() {
      Map<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("cat", 3);
      unfiltered.put("dog", 2);
      unfiltered.put("horse", 5);
      Predicate<Entry<?, ?>> predicate = new Predicate<Entry<?, ?>>() {
        @Override
        public boolean apply(Entry<?, ?> input) {
          return "cat".equals(input.getKey()) || Integer.valueOf(2) == input.getValue();
        }
      };
      Map<String, Integer> filtered = Maps.filterEntries(unfiltered, predicate);
      assertEquals(ImmutableMap.of("cat", 3, "dog", 2), filtered);
    }
  }

  public static class FilteredSortedMapTest extends FilteredMapTest {
    @Override
    SortedMap<String, Integer> createUnfiltered() {
      return Maps.newTreeMap();
    }

    public void testFilterKeysIdentifiesSortedMap() {
      SortedMap<String, Integer> map = createUnfiltered();
      assertTrue(Maps.filterKeys((Map<String, Integer>) map, NOT_LENGTH_3) instanceof SortedMap);
    }

    public void testFilterValuesIdentifiesSortedMap() {
      SortedMap<String, Integer> map = createUnfiltered();
      assertTrue(Maps.filterValues((Map<String, Integer>) map, EVEN) instanceof SortedMap);
    }

    public void testFilterEntriesIdentifiesSortedMap() {
      SortedMap<String, Integer> map = createUnfiltered();
      assertTrue(Maps.filterEntries((Map<String, Integer>) map, CORRECT_LENGTH) instanceof SortedMap);
    }

    public void testFirstAndLastKeyFilteredMap() {
      SortedMap<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("apple", 2);
      unfiltered.put("banana", 6);
      unfiltered.put("cat", 3);
      unfiltered.put("dog", 5);

      SortedMap<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);
      assertEquals("banana", filtered.firstKey());
      assertEquals("cat", filtered.lastKey());
    }

    public void testHeadSubTailMap_FilteredMap() {
      SortedMap<String, Integer> unfiltered = createUnfiltered();
      unfiltered.put("apple", 2);
      unfiltered.put("banana", 6);
      unfiltered.put("cat", 4);
      unfiltered.put("dog", 3);
      SortedMap<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);

      assertEquals(ImmutableMap.of("banana", 6), filtered.headMap("dog"));
      assertEquals(ImmutableMap.of(), filtered.headMap("banana"));
      assertEquals(ImmutableMap.of("banana", 6, "dog", 3), filtered.headMap("emu"));

      assertEquals(ImmutableMap.of("banana", 6), filtered.subMap("banana", "dog"));
      assertEquals(ImmutableMap.of("dog", 3), filtered.subMap("cat", "emu"));

      assertEquals(ImmutableMap.of("dog", 3), filtered.tailMap("cat"));
      assertEquals(ImmutableMap.of("banana", 6, "dog", 3), filtered.tailMap("banana"));
    }
  }

  public static class FilteredBiMapTest extends FilteredMapTest {
    @Override
    BiMap<String, Integer> createUnfiltered() {
      return HashBiMap.create();
    }

    public void testFilterKeysIdentifiesBiMap() {
      BiMap<String, Integer> map = createUnfiltered();
      assertTrue(Maps.filterKeys((Map<String, Integer>) map, NOT_LENGTH_3) instanceof BiMap);
    }

    public void testFilterValuesIdentifiesBiMap() {
      BiMap<String, Integer> map = createUnfiltered();
      assertTrue(Maps.filterValues((Map<String, Integer>) map, EVEN) instanceof BiMap);
    }

    public void testFilterEntriesIdentifiesBiMap() {
      BiMap<String, Integer> map = createUnfiltered();
      assertTrue(Maps.filterEntries((Map<String, Integer>) map, CORRECT_LENGTH) instanceof BiMap);
    }
  }

  public void testTransformValues() {
    Map<String, Integer> map = ImmutableMap.of("a", 4, "b", 9);
    Map<String, Double> transformed = transformValues(map, SQRT_FUNCTION);

    assertEquals(ImmutableMap.of("a", 2.0, "b", 3.0), transformed);
  }

  public void testTransformValuesSecretlySorted() {
    Map<String, Integer> map = sortedNotNavigable(ImmutableSortedMap.of("a", 4, "b", 9));
    Map<String, Double> transformed = transformValues(map, SQRT_FUNCTION);

    assertEquals(ImmutableMap.of("a", 2.0, "b", 3.0), transformed);
    assertTrue(transformed instanceof SortedMap);
  }

  public void testTransformEntries() {
    Map<String, String> map = ImmutableMap.of("a", "4", "b", "9");
    EntryTransformer<String, String, String> concat = new EntryTransformer<String, String, String>() {
      @Override
      public String transformEntry(String key, String value) {
        return key + value;
      }
    };
    Map<String, String> transformed = transformEntries(map, concat);

    assertEquals(ImmutableMap.of("a", "a4", "b", "b9"), transformed);
  }

  public void testTransformEntriesSecretlySorted() {
    Map<String, String> map = ImmutableSortedMap.of("a", "4", "b", "9");
    EntryTransformer<String, String, String> concat = new EntryTransformer<String, String, String>() {
      @Override
      public String transformEntry(String key, String value) {
        return key + value;
      }
    };
    Map<String, String> transformed = transformEntries(map, concat);

    assertEquals(ImmutableMap.of("a", "a4", "b", "b9"), transformed);
    assertTrue(transformed instanceof SortedMap);
  }

  public void testTransformEntriesGenerics() {
    Map<Object, Object> map1 = ImmutableMap.<Object, Object>of(1, 2);
    Map<Object, Number> map2 = ImmutableMap.<Object, Number>of(1, 2);
    Map<Object, Integer> map3 = ImmutableMap.<Object, Integer>of(1, 2);
    Map<Number, Object> map4 = ImmutableMap.<Number, Object>of(1, 2);
    Map<Number, Number> map5 = ImmutableMap.<Number, Number>of(1, 2);
    Map<Number, Integer> map6 = ImmutableMap.<Number, Integer>of(1, 2);
    Map<Integer, Object> map7 = ImmutableMap.<Integer, Object>of(1, 2);
    Map<Integer, Number> map8 = ImmutableMap.<Integer, Number>of(1, 2);
    Map<Integer, Integer> map9 = ImmutableMap.<Integer, Integer>of(1, 2);
    Map<? extends Number, ? extends Number> map0 = ImmutableMap.of(1, 2);

    EntryTransformer<Number, Number, Double> transformer = new EntryTransformer<Number, Number, Double>() {
      @Override
      public Double transformEntry(Number key, Number value) {
        return key.doubleValue() + value.doubleValue();
      }
    };

    Map<Object, Double> objectKeyed;
    Map<Number, Double> numberKeyed;
    Map<Integer, Double> integerKeyed;

    numberKeyed = transformEntries(map5, transformer);
    numberKeyed = transformEntries(map6, transformer);
    integerKeyed = transformEntries(map8, transformer);
    integerKeyed = transformEntries(map9, transformer);

    Map<? extends Number, Double> wildcarded = transformEntries(map0, transformer);

    // Can't loosen the key type:
    // objectKeyed = transformEntries(map5, transformer);
    // objectKeyed = transformEntries(map6, transformer);
    // objectKeyed = transformEntries(map8, transformer);
    // objectKeyed = transformEntries(map9, transformer);
    // numberKeyed = transformEntries(map8, transformer);
    // numberKeyed = transformEntries(map9, transformer);

    // Can't loosen the value type:
    // Map<Number, Number> looseValued1 = transformEntries(map5, transformer);
    // Map<Number, Number> looseValued2 = transformEntries(map6, transformer);
    // Map<Integer, Number> looseValued3 = transformEntries(map8, transformer);
    // Map<Integer, Number> looseValued4 = transformEntries(map9, transformer);

    // Can't call with too loose a key:
    // transformEntries(map1, transformer);
    // transformEntries(map2, transformer);
    // transformEntries(map3, transformer);

    // Can't call with too loose a value:
    // transformEntries(map1, transformer);
    // transformEntries(map4, transformer);
    // transformEntries(map7, transformer);
  }

  public void testTransformEntriesExample() {
    Map<String, Boolean> options = ImmutableMap.of("verbose", true, "sort", false);
    EntryTransformer<String, Boolean, String> flagPrefixer = new EntryTransformer<String, Boolean, String>() {
      @Override
      public String transformEntry(String key, Boolean value) {
        return value ? key : "no" + key;
      }
    };
    Map<String, String> transformed = transformEntries(options, flagPrefixer);
    assertEquals("{verbose=verbose, sort=nosort}", transformed.toString());
  }

  // Logically this would accept a NavigableMap, but that won't work under GWT.
  private static <K, V> SortedMap<K, V> sortedNotNavigable(final SortedMap<K, V> map) {
    return new ForwardingSortedMap<K, V>() {
      @Override
      protected SortedMap<K, V> delegate() {
        return map;
      }
    };
  }

  public void testSortedMapTransformValues() {
    SortedMap<String, Integer> map = sortedNotNavigable(ImmutableSortedMap.of("a", 4, "b", 9));
    SortedMap<String, Double> transformed = transformValues(map, SQRT_FUNCTION);

    /*
     * We'd like to sanity check that we didn't get a NavigableMap out, but we
     * can't easily do so while maintaining GWT compatibility.
     */
    assertEquals(ImmutableSortedMap.of("a", 2.0, "b", 3.0), transformed);
  }

  public void testSortedMapTransformEntries() {
    SortedMap<String, String> map = sortedNotNavigable(ImmutableSortedMap.of("a", "4", "b", "9"));
    EntryTransformer<String, String, String> concat = new EntryTransformer<String, String, String>() {
      @Override
      public String transformEntry(String key, String value) {
        return key + value;
      }
    };
    SortedMap<String, String> transformed = transformEntries(map, concat);

    /*
     * We'd like to sanity check that we didn't get a NavigableMap out, but we
     * can't easily do so while maintaining GWT compatibility.
     */
    assertEquals(ImmutableSortedMap.of("a", "a4", "b", "b9"), transformed);
  }

  // Hack for JDK5 type inference.
  private static class ASSERT {
    static <T> CollectionSubject<? extends CollectionSubject<?, T, Collection<T>>, T, Collection<T>> that(
        Collection<T> collection) {
      return Truth.ASSERT.<T, Collection<T>>that(collection);
    }
  }
}