assertEqualCharNodes(Traverser.forTree(TWO_TREES).breadthFirst(charactersOf("ca")), "cadb");
  }

  @Test
  public void forTree_breadthFirst_singleRoot() {
    Iterable<Character> result = Traverser.forTree(SINGLE_ROOT).breadthFirst('a');

    assertEqualCharNodes(result, "a");
  }

  @Test
  public void forTree_breadthFirstIterable_singleRoot() {