/*
 * 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;

import static com.google.common.collect.testing.Helpers.mapEntry;
import static com.google.common.testing.SerializableTester.reserialize;
import static com.google.common.truth.Truth.assertThat;
import static com.google.common.truth.Truth.assertWithMessage;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Equivalence;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableMap.Builder;
import com.google.common.collect.testing.AnEnum;
import com.google.common.collect.testing.CollectionTestSuiteBuilder;
import com.google.common.collect.testing.ListTestSuiteBuilder;
import com.google.common.collect.testing.MapInterfaceTest;
import com.google.common.collect.testing.MapTestSuiteBuilder;
import com.google.common.collect.testing.MinimalSet;
import com.google.common.collect.testing.SampleElements.Colliders;
import com.google.common.collect.testing.SampleElements.Unhashables;
import com.google.common.collect.testing.TestStringMapGenerator;
import com.google.common.collect.testing.UnhashableObject;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.MapFeature;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapCopyOfEntriesGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapCopyOfEnumMapGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapCopyOfGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapEntryListGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapKeyListGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapUnhashableValuesGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapValueListGenerator;
import com.google.common.collect.testing.google.MapGenerators.ImmutableMapValuesAsSingletonSetGenerator;
import com.google.common.testing.CollectorTester;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.NullPointerTester;
import com.google.common.testing.SerializableTester;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collector;
import java.util.stream.Stream;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Tests for {@link ImmutableMap}.
 *
 * @author Kevin Bourrillion
 * @author Jesse Wilson
 */
@GwtCompatible(emulated = true)
@SuppressWarnings("AlwaysThrows")
public class ImmutableMapTest extends TestCase {

  @GwtIncompatible // suite
  public static Test suite() {
    TestSuite suite = new TestSuite();
    suite.addTestSuite(ImmutableMapTest.class);
    suite.addTestSuite(FloodingTest.class);

    suite.addTest(
        MapTestSuiteBuilder.using(new ImmutableMapGenerator())
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE_INCLUDING_VIEWS,
                CollectionFeature.KNOWN_ORDER,
                MapFeature.REJECTS_DUPLICATES_AT_CREATION,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap")
            .createTestSuite());

    suite.addTest(
        MapTestSuiteBuilder.using(
                new TestStringMapGenerator() {
                  @Override
                  protected Map<String, String> create(Entry<String, String>[] entries) {
                    ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
                    builder.putAll(Arrays.asList(entries));
                    return builder.buildJdkBacked();
                  }
                })
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE_INCLUDING_VIEWS,
                CollectionFeature.KNOWN_ORDER,
                MapFeature.REJECTS_DUPLICATES_AT_CREATION,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap [JDK backed]")
            .createTestSuite());

    suite.addTest(
        MapTestSuiteBuilder.using(new ImmutableMapCopyOfGenerator())
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE_INCLUDING_VIEWS,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap.copyOf[Map]")
            .createTestSuite());

    suite.addTest(
        MapTestSuiteBuilder.using(new ImmutableMapCopyOfEntriesGenerator())
            .withFeatures(
                CollectionSize.ANY,
                MapFeature.REJECTS_DUPLICATES_AT_CREATION,
                CollectionFeature.SERIALIZABLE_INCLUDING_VIEWS,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap.copyOf[Iterable<Entry>]")
            .createTestSuite());

    suite.addTest(
        MapTestSuiteBuilder.using(new ImmutableMapCopyOfEnumMapGenerator())
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE_INCLUDING_VIEWS,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap.copyOf[EnumMap]")
            .createTestSuite());

    suite.addTest(
        MapTestSuiteBuilder.using(new ImmutableMapValuesAsSingletonSetGenerator())
            .withFeatures(
                CollectionSize.ANY,
                MapFeature.REJECTS_DUPLICATES_AT_CREATION,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap.asMultimap.asMap")
            .createTestSuite());

    suite.addTest(
        CollectionTestSuiteBuilder.using(new ImmutableMapUnhashableValuesGenerator())
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.KNOWN_ORDER,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .named("ImmutableMap.values, unhashable")
            .createTestSuite());

    suite.addTest(
        ListTestSuiteBuilder.using(new ImmutableMapKeyListGenerator())
            .named("ImmutableMap.keySet.asList")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.REJECTS_DUPLICATES_AT_CREATION,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .createTestSuite());

    suite.addTest(
        ListTestSuiteBuilder.using(new ImmutableMapEntryListGenerator())
            .named("ImmutableMap.entrySet.asList")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.REJECTS_DUPLICATES_AT_CREATION,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .createTestSuite());

    suite.addTest(
        ListTestSuiteBuilder.using(new ImmutableMapValueListGenerator())
            .named("ImmutableMap.values.asList")
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.ALLOWS_NULL_QUERIES)
            .createTestSuite());

    return suite;
  }

  public abstract static class AbstractMapTests<K, V> extends MapInterfaceTest<K, V> {
    public AbstractMapTests() {
      super(false, false, false, false, false);
    }

    @Override
    protected Map<K, V> makeEmptyMap() {
      throw new UnsupportedOperationException();
    }

    private static final Joiner JOINER = Joiner.on(", ");

    @Override
    protected void assertMoreInvariants(Map<K, V> map) {
      // TODO: can these be moved to MapInterfaceTest?
      for (Entry<K, V> entry : map.entrySet()) {
        assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
      }

      assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
      assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());
      assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
      assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());

      assertEquals(MinimalSet.from(map.entrySet()), map.entrySet());
      assertEquals(Sets.newHashSet(map.keySet()), map.keySet());
    }
  }

  public static class MapTests extends AbstractMapTests<String, Integer> {
    @Override
    protected Map<String, Integer> makeEmptyMap() {
      return ImmutableMap.of();
    }

    @Override
    protected Map<String, Integer> makePopulatedMap() {
      return ImmutableMap.of("one", 1, "two", 2, "three", 3);
    }

    @Override
    protected String getKeyNotInPopulatedMap() {
      return "minus one";
    }

    @Override
    protected Integer getValueNotInPopulatedMap() {
      return -1;
    }
  }

  public static class SingletonMapTests extends AbstractMapTests<String, Integer> {
    @Override
    protected Map<String, Integer> makePopulatedMap() {
      return ImmutableMap.of("one", 1);
    }

    @Override
    protected String getKeyNotInPopulatedMap() {
      return "minus one";
    }

    @Override
    protected Integer getValueNotInPopulatedMap() {
      return -1;
    }
  }

  @GwtIncompatible // SerializableTester
  public static class ReserializedMapTests extends AbstractMapTests<String, Integer> {
    @Override
    protected Map<String, Integer> makePopulatedMap() {
      return SerializableTester.reserialize(ImmutableMap.of("one", 1, "two", 2, "three", 3));
    }

    @Override
    protected String getKeyNotInPopulatedMap() {
      return "minus one";
    }

    @Override
    protected Integer getValueNotInPopulatedMap() {
      return -1;
    }
  }

  public static class MapTestsWithBadHashes extends AbstractMapTests<Object, Integer> {

    @Override
    protected Map<Object, Integer> makeEmptyMap() {
      throw new UnsupportedOperationException();
    }

    @Override
    protected Map<Object, Integer> makePopulatedMap() {
      Colliders colliders = new Colliders();
      return ImmutableMap.of(
          colliders.e0(), 0,
          colliders.e1(), 1,
          colliders.e2(), 2,
          colliders.e3(), 3);
    }

    @Override
    protected Object getKeyNotInPopulatedMap() {
      return new Colliders().e4();
    }

    @Override
    protected Integer getValueNotInPopulatedMap() {
      return 4;
    }
  }

  @GwtIncompatible // GWT's ImmutableMap emulation is backed by java.util.HashMap.
  public static class MapTestsWithUnhashableValues
      extends AbstractMapTests<Integer, UnhashableObject> {
    @Override
    protected Map<Integer, UnhashableObject> makeEmptyMap() {
      return ImmutableMap.of();
    }

    @Override
    protected Map<Integer, UnhashableObject> makePopulatedMap() {
      Unhashables unhashables = new Unhashables();
      return ImmutableMap.of(0, unhashables.e0(), 1, unhashables.e1(), 2, unhashables.e2());
    }

    @Override
    protected Integer getKeyNotInPopulatedMap() {
      return 3;
    }

    @Override
    protected UnhashableObject getValueNotInPopulatedMap() {
      return new Unhashables().e3();
    }
  }

  @GwtIncompatible // GWT's ImmutableMap emulation is backed by java.util.HashMap.
  public static class MapTestsWithSingletonUnhashableValue extends MapTestsWithUnhashableValues {
    @Override
    protected Map<Integer, UnhashableObject> makePopulatedMap() {
      Unhashables unhashables = new Unhashables();
      return ImmutableMap.of(0, unhashables.e0());
    }
  }

  public static class CreationTests extends TestCase {
    public void testEmptyBuilder() {
      ImmutableMap<String, Integer> map = new Builder<String, Integer>().buildOrThrow();
      assertEquals(Collections.<String, Integer>emptyMap(), map);
    }

    public void testSingletonBuilder() {
      ImmutableMap<String, Integer> map =
          new Builder<String, Integer>().put("one", 1).buildOrThrow();
      assertMapEquals(map, "one", 1);
    }

    public void testBuilder() {
      ImmutableMap<String, Integer> map =
          new Builder<String, Integer>()
              .put("one", 1)
              .put("two", 2)
              .put("three", 3)
              .put("four", 4)
              .put("five", 5)
              .buildOrThrow();
      assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
    }

    @GwtIncompatible
    public void testBuilderExactlySizedReusesArray() {
      ImmutableMap.Builder<Integer, Integer> builder = ImmutableMap.builderWithExpectedSize(10);
      Entry<Integer, Integer>[] builderArray = builder.entries;
      for (int i = 0; i < 10; i++) {
        builder.put(i, i);
      }
      Entry<Integer, Integer>[] builderArrayAfterPuts = builder.entries;
      RegularImmutableMap<Integer, Integer> map =
          (RegularImmutableMap<Integer, Integer>) builder.buildOrThrow();
      Entry<Integer, Integer>[] mapInternalArray = map.entries;
      assertSame(builderArray, builderArrayAfterPuts);
      assertSame(builderArray, mapInternalArray);
    }

    public void testBuilder_orderEntriesByValue() {
      ImmutableMap<String, Integer> map =
          new Builder<String, Integer>()
              .orderEntriesByValue(Ordering.natural())
              .put("three", 3)
              .put("one", 1)
              .put("five", 5)
              .put("four", 4)
              .put("two", 2)
              .buildOrThrow();
      assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
    }

    public void testBuilder_orderEntriesByValueAfterExactSizeBuild() {
      Builder<String, Integer> builder =
          new Builder<String, Integer>(2).put("four", 4).put("one", 1);
      ImmutableMap<String, Integer> keyOrdered = builder.buildOrThrow();
      ImmutableMap<String, Integer> valueOrdered =
          builder.orderEntriesByValue(Ordering.natural()).buildOrThrow();
      assertMapEquals(keyOrdered, "four", 4, "one", 1);
      assertMapEquals(valueOrdered, "one", 1, "four", 4);
    }

    public void testBuilder_orderEntriesByValue_usedTwiceFails() {
      ImmutableMap.Builder<String, Integer> builder =
          new Builder<String, Integer>().orderEntriesByValue(Ordering.natural());
      try {
        builder.orderEntriesByValue(Ordering.natural());
        fail("Expected IllegalStateException");
      } catch (IllegalStateException expected) {
      }
    }

    @GwtIncompatible // we haven't implemented this
    public void testBuilder_orderEntriesByValue_keepingLast() {
      ImmutableMap.Builder<String, Integer> builder =
          new Builder<String, Integer>()
              .orderEntriesByValue(Ordering.natural())
              .put("three", 3)
              .put("one", 1)
              .put("five", 5)
              .put("four", 3)
              .put("four", 5)
              .put("four", 4) // this should win because it's last
              .put("two", 2);
      assertMapEquals(
          builder.buildKeepingLast(), "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
      try {
        builder.buildOrThrow();
        fail("Expected exception from duplicate keys");
      } catch (IllegalArgumentException expected) {
      }
    }

    @GwtIncompatible // we haven't implemented this
    public void testBuilder_orderEntriesByValue_keepingLast_builderSizeFieldPreserved() {
      ImmutableMap.Builder<String, Integer> builder =
          new Builder<String, Integer>()
              .orderEntriesByValue(Ordering.natural())
              .put("one", 1)
              .put("one", 1);
      assertMapEquals(builder.buildKeepingLast(), "one", 1);
      try {
        builder.buildOrThrow();
        fail("Expected exception from duplicate keys");
      } catch (IllegalArgumentException expected) {
      }
    }

    public void testBuilder_withImmutableEntry() {
      ImmutableMap<String, Integer> map =
          new Builder<String, Integer>().put(Maps.immutableEntry("one", 1)).buildOrThrow();
      assertMapEquals(map, "one", 1);
    }

    public void testBuilder_withImmutableEntryAndNullContents() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.put(Maps.immutableEntry("one", (Integer) null));
        fail();
      } catch (NullPointerException expected) {
      }
      try {
        builder.put(Maps.immutableEntry((String) null, 1));
        fail();
      } catch (NullPointerException expected) {
      }
    }

    private static class StringHolder {
      String string;
    }

    public void testBuilder_withMutableEntry() {
      ImmutableMap.Builder<String, Integer> builder = new Builder<>();
      final StringHolder holder = new StringHolder();
      holder.string = "one";
      Entry<String, Integer> entry =
          new AbstractMapEntry<String, Integer>() {
            @Override
            public String getKey() {
              return holder.string;
            }

            @Override
            public Integer getValue() {
              return 1;
            }
          };

      builder.put(entry);
      holder.string = "two";
      assertMapEquals(builder.buildOrThrow(), "one", 1);
    }

    public void testBuilderPutAllWithEmptyMap() {
      ImmutableMap<String, Integer> map =
          new Builder<String, Integer>()
              .putAll(Collections.<String, Integer>emptyMap())
              .buildOrThrow();
      assertEquals(Collections.<String, Integer>emptyMap(), map);
    }

    public void testBuilderPutAll() {
      Map<String, Integer> toPut = new LinkedHashMap<>();
      toPut.put("one", 1);
      toPut.put("two", 2);
      toPut.put("three", 3);
      Map<String, Integer> moreToPut = new LinkedHashMap<>();
      moreToPut.put("four", 4);
      moreToPut.put("five", 5);

      ImmutableMap<String, Integer> map =
          new Builder<String, Integer>().putAll(toPut).putAll(moreToPut).buildOrThrow();
      assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
    }

    public void testBuilderReuse() {
      Builder<String, Integer> builder = new Builder<>();
      ImmutableMap<String, Integer> mapOne = builder.put("one", 1).put("two", 2).buildOrThrow();
      ImmutableMap<String, Integer> mapTwo = builder.put("three", 3).put("four", 4).buildOrThrow();

      assertMapEquals(mapOne, "one", 1, "two", 2);
      assertMapEquals(mapTwo, "one", 1, "two", 2, "three", 3, "four", 4);
    }

    public void testBuilderPutNullKeyFailsAtomically() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.put(null, 1);
        fail();
      } catch (NullPointerException expected) {
      }
      builder.put("foo", 2);
      assertMapEquals(builder.buildOrThrow(), "foo", 2);
    }

    public void testBuilderPutImmutableEntryWithNullKeyFailsAtomically() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.put(Maps.immutableEntry((String) null, 1));
        fail();
      } catch (NullPointerException expected) {
      }
      builder.put("foo", 2);
      assertMapEquals(builder.buildOrThrow(), "foo", 2);
    }

    // for GWT compatibility
    static class SimpleEntry<K, V> extends AbstractMapEntry<K, V> {
      public K key;
      public V value;

      SimpleEntry(K key, V value) {
        this.key = key;
        this.value = value;
      }

      @Override
      public K getKey() {
        return key;
      }

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

    public void testBuilderPutMutableEntryWithNullKeyFailsAtomically() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.put(new SimpleEntry<String, Integer>(null, 1));
        fail();
      } catch (NullPointerException expected) {
      }
      builder.put("foo", 2);
      assertMapEquals(builder.buildOrThrow(), "foo", 2);
    }

    public void testBuilderPutNullKey() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.put(null, 1);
        fail();
      } catch (NullPointerException expected) {
      }
    }

    public void testBuilderPutNullValue() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.put("one", null);
        fail();
      } catch (NullPointerException expected) {
      }
    }

    public void testBuilderPutNullKeyViaPutAll() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.putAll(Collections.<String, Integer>singletonMap(null, 1));
        fail();
      } catch (NullPointerException expected) {
      }
    }

    public void testBuilderPutNullValueViaPutAll() {
      Builder<String, Integer> builder = new Builder<>();
      try {
        builder.putAll(Collections.<String, Integer>singletonMap("one", null));
        fail();
      } catch (NullPointerException expected) {
      }
    }

    public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
      Builder<String, Integer> builder =
          new Builder<String, Integer>()
              .put("one", 1)
              .put("one", 1); // throwing on this line might be better but it's too late to change

      try {
        builder.buildOrThrow();
        fail();
      } catch (IllegalArgumentException expected) {
      }
    }

    public void testBuildKeepingLast_allowsOverwrite() {
      Builder<Integer, String> builder =
          new Builder<Integer, String>()
              .put(1, "un")
              .put(2, "deux")
              .put(70, "soixante-dix")
              .put(70, "septante")
              .put(70, "seventy")
              .put(1, "one")
              .put(2, "two");
      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
      assertMapEquals(map, 1, "one", 2, "two", 70, "seventy");
    }

    public void testBuildKeepingLast_smallTableSameHash() {
      String key1 = "QED";
      String key2 = "R&D";
      assertThat(key1.hashCode()).isEqualTo(key2.hashCode());
      ImmutableMap<String, Integer> map =
          ImmutableMap.<String, Integer>builder()
              .put(key1, 1)
              .put(key2, 2)
              .put(key1, 3)
              .put(key2, 4)
              .buildKeepingLast();
      assertMapEquals(map, key1, 3, key2, 4);
    }

    // The java7 branch has different code depending on whether the entry indexes fit in a byte,
    // short, or int. The small table in testBuildKeepingLast_allowsOverwrite will test the byte
    // case. This method tests the short case.
    public void testBuildKeepingLast_shortTable() {
      Builder<Integer, String> builder = ImmutableMap.builder();
      Map<Integer, String> expected = new LinkedHashMap<>();
      for (int i = 0; i < 1000; i++) {
        // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
        // duplicates.
        Integer key = i & ~1;
        String value = String.valueOf(i);
        builder.put(key, value);
        expected.put(key, value);
      }
      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
      assertThat(map).hasSize(500);
      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
    }

    // This method tests the int case.
    public void testBuildKeepingLast_bigTable() {
      Builder<Integer, String> builder = ImmutableMap.builder();
      Map<Integer, String> expected = new LinkedHashMap<>();
      for (int i = 0; i < 200_000; i++) {
        // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
        // duplicates.
        Integer key = i & ~1;
        String value = String.valueOf(i);
        builder.put(key, value);
        expected.put(key, value);
      }
      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
      assertThat(map).hasSize(100_000);
      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
    }

    private static class ClassWithTerribleHashCode
        implements Comparable<ClassWithTerribleHashCode> {
      private final int value;

      ClassWithTerribleHashCode(int value) {
        this.value = value;
      }

      @Override
      public int compareTo(ClassWithTerribleHashCode that) {
        return Integer.compare(this.value, that.value);
      }

      @Override
      public boolean equals(Object x) {
        return x instanceof ClassWithTerribleHashCode
            && ((ClassWithTerribleHashCode) x).value == value;
      }

      @Override
      public int hashCode() {
        return 23;
      }

      @Override
      public String toString() {
        return "ClassWithTerribleHashCode(" + value + ")";
      }
    }

    @GwtIncompatible
    public void testBuildKeepingLast_collisions() {
      Map<ClassWithTerribleHashCode, Integer> expected = new LinkedHashMap<>();
      Builder<ClassWithTerribleHashCode, Integer> builder = new Builder<>();
      int size = RegularImmutableMap.MAX_HASH_BUCKET_LENGTH + 10;
      for (int i = 0; i < size; i++) {
        ClassWithTerribleHashCode key = new ClassWithTerribleHashCode(i);
        builder.put(key, i);
        builder.put(key, -i);
        expected.put(key, -i);
      }
      ImmutableMap<ClassWithTerribleHashCode, Integer> map = builder.buildKeepingLast();
      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
      assertThat(map).isInstanceOf(JdkBackedImmutableMap.class);
    }

    @GwtIncompatible // Pattern, Matcher
    public void testBuilder_keepingLast_thenOrThrow() {
      ImmutableMap.Builder<String, Integer> builder =
          new Builder<String, Integer>()
              .put("three", 3)
              .put("one", 1)
              .put("five", 5)
              .put("four", 3)
              .put("four", 5)
              .put("four", 4) // this should win because it's last
              .put("two", 2);
      assertMapEquals(
          builder.buildKeepingLast(), "three", 3, "one", 1, "five", 5, "four", 4, "two", 2);
      try {
        builder.buildOrThrow();
        fail("Expected exception from duplicate keys");
      } catch (IllegalArgumentException expected) {
        // We don't really care which values the exception message contains, but they should be
        // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
        // not being true.
        Pattern pattern =
            Pattern.compile("Multiple entries with same key: four=(.*) and four=(.*)");
        assertThat(expected).hasMessageThat().matches(pattern);
        Matcher matcher = pattern.matcher(expected.getMessage());
        assertThat(matcher.matches()).isTrue();
        assertThat(matcher.group(1)).isNotEqualTo(matcher.group(2));
      }
    }

    public void testOf() {
      assertMapEquals(ImmutableMap.of("one", 1), "one", 1);
      assertMapEquals(ImmutableMap.of("one", 1, "two", 2), "one", 1, "two", 2);
      assertMapEquals(
          ImmutableMap.of("one", 1, "two", 2, "three", 3), "one", 1, "two", 2, "three", 3);
      assertMapEquals(
          ImmutableMap.of("one", 1, "two", 2, "three", 3, "four", 4),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4);
      assertMapEquals(
          ImmutableMap.of("one", 1, "two", 2, "three", 3, "four", 4, "five", 5),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4,
          "five",
          5);
      assertMapEquals(
          ImmutableMap.of(
              "one", 1,
              "two", 2,
              "three", 3,
              "four", 4,
              "five", 5,
              "six", 6),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4,
          "five",
          5,
          "six",
          6);
      assertMapEquals(
          ImmutableMap.of(
              "one", 1,
              "two", 2,
              "three", 3,
              "four", 4,
              "five", 5,
              "six", 6,
              "seven", 7),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4,
          "five",
          5,
          "six",
          6,
          "seven",
          7);
      assertMapEquals(
          ImmutableMap.of(
              "one", 1,
              "two", 2,
              "three", 3,
              "four", 4,
              "five", 5,
              "six", 6,
              "seven", 7,
              "eight", 8),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4,
          "five",
          5,
          "six",
          6,
          "seven",
          7,
          "eight",
          8);
      assertMapEquals(
          ImmutableMap.of(
              "one", 1,
              "two", 2,
              "three", 3,
              "four", 4,
              "five", 5,
              "six", 6,
              "seven", 7,
              "eight", 8,
              "nine", 9),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4,
          "five",
          5,
          "six",
          6,
          "seven",
          7,
          "eight",
          8,
          "nine",
          9);
      assertMapEquals(
          ImmutableMap.of(
              "one", 1,
              "two", 2,
              "three", 3,
              "four", 4,
              "five", 5,
              "six", 6,
              "seven", 7,
              "eight", 8,
              "nine", 9,
              "ten", 10),
          "one",
          1,
          "two",
          2,
          "three",
          3,
          "four",
          4,
          "five",
          5,
          "six",
          6,
          "seven",
          7,
          "eight",
          8,
          "nine",
          9,
          "ten",
          10);
    }

    public void testOfNullKey() {
      try {
        ImmutableMap.of(null, 1);
        fail();
      } catch (NullPointerException expected) {
      }

      try {
        ImmutableMap.of("one", 1, null, 2);
        fail();
      } catch (NullPointerException expected) {
      }
    }

    public void testOfNullValue() {
      try {
        ImmutableMap.of("one", null);
        fail();
      } catch (NullPointerException expected) {
      }

      try {
        ImmutableMap.of("one", 1, "two", null);
        fail();
      } catch (NullPointerException expected) {
      }
    }

    public void testOfWithDuplicateKey() {
      try {
        ImmutableMap.of("one", 1, "one", 1);
        fail();
      } catch (IllegalArgumentException expected) {
      }
    }

    public void testCopyOfEmptyMap() {
      ImmutableMap<String, Integer> copy =
          ImmutableMap.copyOf(Collections.<String, Integer>emptyMap());
      assertEquals(Collections.<String, Integer>emptyMap(), copy);
      assertSame(copy, ImmutableMap.copyOf(copy));
    }

    public void testCopyOfSingletonMap() {
      ImmutableMap<String, Integer> copy = ImmutableMap.copyOf(Collections.singletonMap("one", 1));
      assertMapEquals(copy, "one", 1);
      assertSame(copy, ImmutableMap.copyOf(copy));
    }

    public void testCopyOf() {
      Map<String, Integer> original = new LinkedHashMap<>();
      original.put("one", 1);
      original.put("two", 2);
      original.put("three", 3);

      ImmutableMap<String, Integer> copy = ImmutableMap.copyOf(original);
      assertMapEquals(copy, "one", 1, "two", 2, "three", 3);
      assertSame(copy, ImmutableMap.copyOf(copy));
    }

    public void testToImmutableMap() {
      Collector<Entry<String, Integer>, ?, ImmutableMap<String, Integer>> collector =
          ImmutableMap.toImmutableMap(Entry::getKey, Entry::getValue);
      Equivalence<ImmutableMap<String, Integer>> equivalence =
          Equivalence.equals()
              .<Entry<String, Integer>>pairwise()
              .onResultOf(ImmutableMap::entrySet);
      CollectorTester.of(collector, equivalence)
          .expectCollects(
              ImmutableMap.of("one", 1, "two", 2, "three", 3),
              mapEntry("one", 1),
              mapEntry("two", 2),
              mapEntry("three", 3));
    }

    public void testToImmutableMap_exceptionOnDuplicateKey() {
      Collector<Entry<String, Integer>, ?, ImmutableMap<String, Integer>> collector =
          ImmutableMap.toImmutableMap(Entry::getKey, Entry::getValue);
      try {
        Stream.of(mapEntry("one", 1), mapEntry("one", 11)).collect(collector);
        fail("Expected IllegalArgumentException");
      } catch (IllegalArgumentException expected) {
      }
    }

    public void testToImmutableMapMerging() {
      Collector<Entry<String, Integer>, ?, ImmutableMap<String, Integer>> collector =
          ImmutableMap.toImmutableMap(Entry::getKey, Entry::getValue, Integer::sum);
      Equivalence<ImmutableMap<String, Integer>> equivalence =
          Equivalence.equals()
              .<Entry<String, Integer>>pairwise()
              .onResultOf(ImmutableMap::entrySet);
      CollectorTester.of(collector, equivalence)
          .expectCollects(
              ImmutableMap.of("one", 1, "two", 4, "three", 3),
              mapEntry("one", 1),
              mapEntry("two", 2),
              mapEntry("three", 3),
              mapEntry("two", 2));
    }
  }

  public void testNullGet() {
    ImmutableMap<String, Integer> map = ImmutableMap.of("one", 1);
    assertNull(map.get(null));
  }

  public void testAsMultimap() {
    ImmutableMap<String, Integer> map =
        ImmutableMap.of("one", 1, "won", 1, "two", 2, "too", 2, "three", 3);
    ImmutableSetMultimap<String, Integer> expected =
        ImmutableSetMultimap.of("one", 1, "won", 1, "two", 2, "too", 2, "three", 3);
    assertEquals(expected, map.asMultimap());
  }

  public void testAsMultimapWhenEmpty() {
    ImmutableMap<String, Integer> map = ImmutableMap.of();
    ImmutableSetMultimap<String, Integer> expected = ImmutableSetMultimap.of();
    assertEquals(expected, map.asMultimap());
  }

  public void testAsMultimapCaches() {
    ImmutableMap<String, Integer> map = ImmutableMap.of("one", 1);
    ImmutableSetMultimap<String, Integer> multimap1 = map.asMultimap();
    ImmutableSetMultimap<String, Integer> multimap2 = map.asMultimap();
    assertEquals(1, multimap1.asMap().size());
    assertSame(multimap1, multimap2);
  }

  @GwtIncompatible // NullPointerTester
  public void testNullPointers() {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicStaticMethods(ImmutableMap.class);
    tester.testAllPublicInstanceMethods(new ImmutableMap.Builder<Object, Object>());
    tester.testAllPublicInstanceMethods(ImmutableMap.of());
    tester.testAllPublicInstanceMethods(ImmutableMap.of("one", 1));
    tester.testAllPublicInstanceMethods(ImmutableMap.of("one", 1, "two", 2, "three", 3));
  }

  private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
    Map<Object, Object> expected = new LinkedHashMap<>();
    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
    }
    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
  }

  private static class IntHolder implements Serializable {
    public int value;

    public IntHolder(int value) {
      this.value = value;
    }

    @Override
    public boolean equals(Object o) {
      return (o instanceof IntHolder) && ((IntHolder) o).value == value;
    }

    @Override
    public int hashCode() {
      return value;
    }

    private static final long serialVersionUID = 5;
  }

  public void testMutableValues() {
    IntHolder holderA = new IntHolder(1);
    IntHolder holderB = new IntHolder(2);
    Map<String, IntHolder> map = ImmutableMap.of("a", holderA, "b", holderB);
    holderA.value = 3;
    assertTrue(map.entrySet().contains(Maps.immutableEntry("a", new IntHolder(3))));
    Map<String, Integer> intMap = ImmutableMap.of("a", 3, "b", 2);
    assertEquals(intMap.hashCode(), map.entrySet().hashCode());
    assertEquals(intMap.hashCode(), map.hashCode());
  }

  public void testCopyOfEnumMap() {
    EnumMap<AnEnum, String> map = new EnumMap<>(AnEnum.class);
    map.put(AnEnum.B, "foo");
    map.put(AnEnum.C, "bar");
    assertTrue(ImmutableMap.copyOf(map) instanceof ImmutableEnumMap);
  }

  @GwtIncompatible // SerializableTester
  public void testViewSerialization() {
    Map<String, Integer> map = ImmutableMap.of("one", 1, "two", 2, "three", 3);
    LenientSerializableTester.reserializeAndAssertLenient(map.entrySet());
    LenientSerializableTester.reserializeAndAssertLenient(map.keySet());

    Collection<Integer> reserializedValues = reserialize(map.values());
    assertEquals(Lists.newArrayList(map.values()), Lists.newArrayList(reserializedValues));
    assertTrue(reserializedValues instanceof ImmutableCollection);
  }

  @GwtIncompatible // SerializableTester
  public void testKeySetIsSerializable_regularImmutableMap() {
    class NonSerializableClass {}

    Map<String, NonSerializableClass> map =
        RegularImmutableMap.fromEntries(ImmutableMap.entryOf("one", new NonSerializableClass()));
    Set<String> set = map.keySet();

    LenientSerializableTester.reserializeAndAssertLenient(set);
  }

  @GwtIncompatible // SerializableTester
  public void testKeySetIsSerializable_jdkBackedImmutableMap() {
    class NonSerializableClass {}

    Entry<String, NonSerializableClass>[] entries =
        arrayOf(ImmutableMap.entryOf("one", new NonSerializableClass()));

    ImmutableMap<String, NonSerializableClass> map =
        JdkBackedImmutableMap.create(1, entries, /* throwIfDuplicateKeys= */ true);
    Set<String> set = map.keySet();

    LenientSerializableTester.reserializeAndAssertLenient(set);
  }

  @GwtIncompatible // SerializableTester
  public void testValuesCollectionIsSerializable_regularImmutableMap() {
    class NonSerializableClass {}

    Map<NonSerializableClass, String> map =
        RegularImmutableMap.fromEntries(ImmutableMap.entryOf(new NonSerializableClass(), "value"));
    Collection<String> collection = map.values();

    LenientSerializableTester.reserializeAndAssertElementsEqual(collection);
  }

  @GwtIncompatible // SerializableTester
  public void testValuesCollectionIsSerializable_jdkBackedImmutableMap() {
    class NonSerializableClass {}

    Entry<NonSerializableClass, String>[] entries =
        arrayOf(ImmutableMap.entryOf(new NonSerializableClass(), "value"));

    ImmutableMap<NonSerializableClass, String> map =
        JdkBackedImmutableMap.create(1, entries, /* throwIfDuplicateKeys= */ true);
    Collection<String> collection = map.values();

    LenientSerializableTester.reserializeAndAssertElementsEqual(collection);
  }

  // TODO: Re-enable this test after moving to new serialization format in ImmutableMap.
  @GwtIncompatible // SerializableTester
  @SuppressWarnings("unchecked")
  public void ignore_testSerializationNoDuplication_regularImmutableMap() throws Exception {
    // Tests that searializing a map, its keySet, and values only writes the underlying data once.

    Entry<Integer, Integer>[] entries = (Entry<Integer, Integer>[]) new Entry<?, ?>[1000];
    for (int i = 0; i < 1000; i++) {
      entries[i] = ImmutableMap.entryOf(i, i);
    }

    ImmutableMap<Integer, Integer> map = RegularImmutableMap.fromEntries(entries);
    Set<Integer> keySet = map.keySet();
    Collection<Integer> values = map.values();

    ByteArrayOutputStream bytes = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bytes);
    oos.writeObject(map);
    oos.flush();

    int mapSize = bytes.size();
    oos.writeObject(keySet);
    oos.writeObject(values);
    oos.close();

    int finalSize = bytes.size();

    assertThat(finalSize - mapSize).isLessThan(100);
  }

  // TODO: Re-enable this test after moving to new serialization format in ImmutableMap.
  @GwtIncompatible // SerializableTester
  @SuppressWarnings("unchecked")
  public void ignore_testSerializationNoDuplication_jdkBackedImmutableMap() throws Exception {
    // Tests that searializing a map, its keySet, and values only writes
    // the underlying data once.

    Entry<Integer, Integer>[] entries = (Entry<Integer, Integer>[]) new Entry<?, ?>[1000];
    for (int i = 0; i < 1000; i++) {
      entries[i] = ImmutableMap.entryOf(i, i);
    }

    ImmutableMap<Integer, Integer> map =
        JdkBackedImmutableMap.create(entries.length, entries, /* throwIfDuplicateKeys= */ true);
    Set<Integer> keySet = map.keySet();
    Collection<Integer> values = map.values();

    ByteArrayOutputStream bytes = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bytes);
    oos.writeObject(map);
    oos.flush();

    int mapSize = bytes.size();
    oos.writeObject(keySet);
    oos.writeObject(values);
    oos.close();

    int finalSize = bytes.size();

    assertThat(finalSize - mapSize).isLessThan(100);
  }

  private static <T> T[] arrayOf(T... objs) {
    return objs;
  }

  @GwtIncompatible("assumptions about splitting")
  public void testKeySetSplittable() {
    ImmutableMap<Integer, Integer> map =
        ImmutableMap.<Integer, Integer>builder()
            .put(1, 1)
            .put(2, 2)
            .put(3, 3)
            .put(4, 4)
            .put(5, 5)
            .put(6, 6)
            .buildOrThrow();
    assertNotNull(map.keySet().spliterator().trySplit());
  }

  public void testEquals() {
    new EqualsTester()
        .addEqualityGroup(
            ImmutableMap.of(),
            ImmutableMap.builder().buildOrThrow(),
            ImmutableMap.ofEntries(),
            map())
        .addEqualityGroup(
            ImmutableMap.of(1, 1),
            ImmutableMap.builder().put(1, 1).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1)),
            map(1, 1))
        .addEqualityGroup(
            ImmutableMap.of(1, 1, 2, 2),
            ImmutableMap.builder().put(1, 1).put(2, 2).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2)),
            map(1, 1, 2, 2))
        .addEqualityGroup(
            ImmutableMap.of(1, 1, 2, 2, 3, 3),
            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3)),
            map(1, 1, 2, 2, 3, 3))
        .addEqualityGroup(
            ImmutableMap.of(1, 4, 2, 2, 3, 3),
            ImmutableMap.builder().put(1, 4).put(2, 2).put(3, 3).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 4), entry(2, 2), entry(3, 3)),
            map(1, 4, 2, 2, 3, 3))
        .addEqualityGroup(
            ImmutableMap.of(1, 1, 2, 4, 3, 3),
            ImmutableMap.builder().put(1, 1).put(2, 4).put(3, 3).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1), entry(2, 4), entry(3, 3)),
            map(1, 1, 2, 4, 3, 3))
        .addEqualityGroup(
            ImmutableMap.of(1, 1, 2, 2, 3, 4),
            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 4).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 4)),
            map(1, 1, 2, 2, 3, 4))
        .addEqualityGroup(
            ImmutableMap.of(1, 2, 2, 3, 3, 1),
            ImmutableMap.builder().put(1, 2).put(2, 3).put(3, 1).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 2), entry(2, 3), entry(3, 1)),
            map(1, 2, 2, 3, 3, 1))
        .addEqualityGroup(
            ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4),
            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).put(4, 4).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3), entry(4, 4)),
            map(1, 1, 2, 2, 3, 3, 4, 4))
        .addEqualityGroup(
            ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4, 5, 5),
            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).put(4, 4).put(5, 5).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3), entry(4, 4), entry(5, 5)),
            map(1, 1, 2, 2, 3, 3, 4, 4, 5, 5))
        .testEquals();
  }

  public void testOfEntriesNull() {
    Entry<Integer, Integer> nullKey = entry(null, 23);
    try {
      ImmutableMap.ofEntries(nullKey);
      fail();
    } catch (NullPointerException expected) {
    }
    Entry<Integer, Integer> nullValue = entry(23, null);
    try {
      ImmutableMap.ofEntries(nullValue);
      fail();
    } catch (NullPointerException expected) {
    }
  }

  private static <T> Map<T, T> map(T... keysAndValues) {
    assertThat(keysAndValues.length % 2).isEqualTo(0);
    LinkedHashMap<T, T> map = new LinkedHashMap<>();
    for (int i = 0; i < keysAndValues.length; i += 2) {
      T key = keysAndValues[i];
      T value = keysAndValues[i + 1];
      T old = map.put(key, value);
      assertWithMessage("Key %s set to %s and %s", key, value, old).that(old).isNull();
    }
    return map;
  }

  private static <T> Entry<T, T> entry(T key, T value) {
    return new AbstractMap.SimpleImmutableEntry<>(key, value);
  }

  public void testCopyOfMutableEntryList() {
    List<Entry<String, String>> entryList =
        Arrays.asList(
            new AbstractMap.SimpleEntry<>("a", "1"), new AbstractMap.SimpleEntry<>("b", "2"));
    ImmutableMap<String, String> map = ImmutableMap.copyOf(entryList);
    assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
    entryList.get(0).setValue("3");
    assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
  }

  public void testBuilderPutAllEntryList() {
    List<Entry<String, String>> entryList =
        Arrays.asList(
            new AbstractMap.SimpleEntry<>("a", "1"), new AbstractMap.SimpleEntry<>("b", "2"));
    ImmutableMap<String, String> map =
        ImmutableMap.<String, String>builder().putAll(entryList).buildOrThrow();
    assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
    entryList.get(0).setValue("3");
    assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
  }

  public void testBuilderPutAllEntryListJdkBacked() {
    List<Entry<String, String>> entryList =
        Arrays.asList(
            new AbstractMap.SimpleEntry<>("a", "1"), new AbstractMap.SimpleEntry<>("b", "2"));
    ImmutableMap<String, String> map =
        ImmutableMap.<String, String>builder().putAll(entryList).buildJdkBacked();
    assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
    entryList.get(0).setValue("3");
    assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
  }

  public static class FloodingTest extends AbstractHashFloodingTest<Map<Object, Object>> {
    public FloodingTest() {
      super(
          Arrays.asList(ConstructionPathway.values()),
          n -> n * Math.log(n),
          ImmutableList.of(QueryOp.MAP_GET));
    }

    /** All the ways to create an ImmutableMap. */
    enum ConstructionPathway implements Construction<Map<Object, Object>> {
      COPY_OF_MAP {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          Map<Object, Object> sourceMap = new LinkedHashMap<>();
          for (Object k : keys) {
            if (sourceMap.put(k, "dummy value") != null) {
              throw new UnsupportedOperationException("duplicate key");
            }
          }
          return ImmutableMap.copyOf(sourceMap);
        }
      },
      COPY_OF_ENTRIES {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          return ImmutableMap.copyOf(
              Lists.transform(keys, k -> Maps.immutableEntry(k, "dummy value")));
        }
      },
      BUILDER_PUT_ONE_BY_ONE {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          ImmutableMap.Builder<Object, Object> builder = ImmutableMap.builder();
          for (Object k : keys) {
            builder.put(k, "dummy value");
          }
          return builder.buildOrThrow();
        }
      },
      BUILDER_PUT_ENTRIES_ONE_BY_ONE {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          ImmutableMap.Builder<Object, Object> builder = ImmutableMap.builder();
          for (Object k : keys) {
            builder.put(Maps.immutableEntry(k, "dummy value"));
          }
          return builder.buildOrThrow();
        }
      },
      BUILDER_PUT_ALL_MAP {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          Map<Object, Object> sourceMap = new LinkedHashMap<>();
          for (Object k : keys) {
            if (sourceMap.put(k, "dummy value") != null) {
              throw new UnsupportedOperationException("duplicate key");
            }
          }
          return ImmutableMap.builder().putAll(sourceMap).buildOrThrow();
        }
      },
      BUILDER_PUT_ALL_ENTRIES {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          return ImmutableMap.builder()
              .putAll(Lists.transform(keys, k -> Maps.immutableEntry(k, "dummy value")))
              .buildOrThrow();
        }
      },
      FORCE_JDK {
        @Override
        public Map<Object, Object> create(List<?> keys) {
          ImmutableMap.Builder<Object, Object> builder = ImmutableMap.builder();
          for (Object k : keys) {
            builder.put(k, "dummy value");
          }
          return builder.buildJdkBacked();
        }
      };
    }
  }
}