Set<String> set = of("a", "b");
    assertEquals(newHashSet("a", "b"), set);
  }

  public void testCreation_threeElements() {
    Set<String> set = of("a", "b", "c");
    assertEquals(newHashSet("a", "b", "c"), set);
  }

  public void testCreation_fourElements() {
    Set<String> set = of("a", "b", "c", "d");
    assertEquals(newHashSet("a", "b", "c", "d"), set);
  }

                immutableEntry("foo", (Collection<Integer>) newHashSet(2, 3, 6)),
                immutableEntry("bar", (Collection<Integer>) newHashSet(4, 5, 10, 11)),
                immutableEntry("baz", (Collection<Integer>) newHashSet(7, 8)),
                immutableEntry("dog", (Collection<Integer>) newHashSet(9)),
                immutableEntry("cat", (Collection<Integer>) newHashSet(12, 13, 14))));

    assertThat(keySet.last()).isEqualTo("google");
    assertEquals(StringLength.COMPARATOR, keySet.comparator());
    assertEquals(Sets.<@Nullable String>newHashSet(null, "tree"), keySet.headSet("yahoo"));
    assertEquals(newHashSet("google"), keySet.tailSet("yahoo"));
    assertEquals(newHashSet("tree"), keySet.subSet("ask", "yahoo"));
  }

  @GwtIncompatible // SerializableTester
  public void testExplicitComparatorSerialization() {

  }

  public void testContains_nonNullSetYes() {
    Iterable<String> set = newHashSet("a", null, "b");
    assertTrue(FluentIterable.from(set).contains("b"));
  }

  public void testContains_nonNullSetNo() {
    Iterable<String> set = newHashSet("a", "b");
    assertFalse(FluentIterable.from(set).contains("c"));
  }

  public void testContains_nonNullIterableYes() {

      }
    };
  }

  public void test_contains_null_set_yes() {
    Iterable<@Nullable String> set = newHashSet("a", null, "b");
    assertTrue(Iterables.contains(set, null));
  }

  public void test_contains_null_set_no() {
    Iterable<String> set = newHashSet("a", "b");
    assertFalse(Iterables.contains(set, null));
  }

  public void test_contains_null_iterable_yes() {

    assertFalse(set.equals(Sets.newTreeSet(asList("a", "b", "d"))));
    assertFalse(Sets.newTreeSet(asList("a", "b", "d")).equals(set));
    assertFalse(set.equals(newHashSet(4, 5, 6)));
    assertFalse(newHashSet(4, 5, 6).equals(set));
  }

  public void testEquals_bothExplicitOrdering() {
    SortedSet<String> set = of("in", "the", "a");
    assertEquals(Sets.newTreeSet(asList("in", "the", "a")), set);

package com.google.common.collect;

import static com.google.common.collect.Maps.immutableEntry;
import static com.google.common.collect.ReflectionFreeAssertThrows.assertThrows;
import static com.google.common.collect.Sets.newHashSet;
import static com.google.common.truth.Truth.assertThat;
import static java.util.Collections.singletonMap;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

    assertFalse(set.equals(Sets.newTreeSet(asList("a", "b", "d"))));
    assertFalse(Sets.newTreeSet(asList("a", "b", "d")).equals(set));
    assertFalse(set.equals(newHashSet(4, 5, 6)));
    assertFalse(newHashSet(4, 5, 6).equals(set));
  }

  public void testEquals_bothExplicitOrdering() {
    SortedSet<String> set = of("in", "the", "a");
    assertEquals(Sets.newTreeSet(asList("in", "the", "a")), set);

  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call
  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) {
    return (elements instanceof Collection)
        ? new HashSet<E>((Collection<? extends E>) elements)
        : newHashSet(elements.iterator());
  }

  /**
   * Creates a <i>mutable</i> {@code HashSet} instance containing the given elements. A very thin

  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call
  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) {
    return (elements instanceof Collection)
        ? new HashSet<E>((Collection<? extends E>) elements)
        : newHashSet(elements.iterator());
  }

  /**
   * Creates a <i>mutable</i> {@code HashSet} instance containing the given elements. A very thin