Set<String> set = copyOf(iterable);
    assertEquals(2, set.size());
    assertTrue(set.contains("a"));
    assertTrue(set.contains("b"));
  }

  public void testCopyOf_plainIterable_iteratesOnce() {
    CountingIterable iterable = new CountingIterable();
    Set<String> unused = copyOf(iterable);
    assertEquals(1, iterable.count);
  }

  public void testCopyOf_shortcut_empty() {

    CountingIterable iterable = new CountingIterable();
    List<String> list = ImmutableList.copyOf(iterable);
    assertEquals(asList("a", "b", "a"), list);
  }

  public void testCopyOf_plainIterable_iteratesOnce() {
    CountingIterable iterable = new CountingIterable();
    ImmutableList<String> unused = ImmutableList.copyOf(iterable);
    assertEquals(1, iterable.count);
  }

    CountingIterable iterable = new CountingIterable();
    List<String> list = ImmutableList.copyOf(iterable);
    assertEquals(asList("a", "b", "a"), list);
  }

  public void testCopyOf_plainIterable_iteratesOnce() {
    CountingIterable iterable = new CountingIterable();
    ImmutableList<String> unused = ImmutableList.copyOf(iterable);
    assertEquals(1, iterable.count);
  }