assertEquals(5, all.size());

    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Buck");
    assertEquals(6, all.size());
    assertEquals(5, immut.size());
    assertEquals(5, mut.size());
  }

  public void testIntersection() {
    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");

    assertEquals(5, all.size());

    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Buck");
    assertEquals(6, all.size());
    assertEquals(5, immut.size());
    assertEquals(5, mut.size());
  }

  public void testIntersection() {
    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");

and even Stigand, the patriotic archbishop of Canterbury, found
it advisable--"'

  `Found WHAT?' said the Duck.

  `Found IT,' the Mouse replied rather crossly:  `of course you
know what "it" means.'

  `I know what "it" means well enough, when I find a thing,' said
the Duck:  `it's generally a frog or a worm.  The question is,
what did the archbishop find?'

and even Stigand, the patriotic archbishop of Canterbury, found
it advisable--"'

  `Found WHAT?' said the Duck.

  `Found IT,' the Mouse replied rather crossly:  `of course you
know what "it" means.'

  `I know what "it" means well enough, when I find a thing,' said
the Duck:  `it's generally a frog or a worm.  The question is,
what did the archbishop find?'