assertEqualCharNodes(traverser.breadthFirst(charactersOf("db")), "db");
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("d")), "d");
  }

  @Test
  public void forGraph_breadthFirst_cycle() {
    Traverser<Character> traverser = Traverser.forGraph(CYCLE_GRAPH);
    assertEqualCharNodes(traverser.breadthFirst('a'), "abcd");
    assertEqualCharNodes(traverser.breadthFirst('b'), "bcda");