fail();
    } catch (NullPointerException expected) {
    }
  }

  private static class CountingIterable implements Iterable<String> {
    int count = 0;

    @Override
    public Iterator<String> iterator() {
      count++;
      return Iterators.forArray("a", "b", "a");
    }
  }

  public void testCopyOf_plainIterable() {
    CountingIterable iterable = new CountingIterable();

      fail();
    } catch (NullPointerException expected) {
    }
  }

  private static class CountingIterable implements Iterable<String> {
    int count = 0;

    @Override
    public Iterator<String> iterator() {
      count++;
      return Iterators.forArray("a", "b", "a");
    }
  }

  public void testCopyOf_plainIterable() {
    CountingIterable iterable = new CountingIterable();