builder.toString().contentEquals(forEachBuilder));
    return builder.toString();
  }

  public void testPreOrder() {
    assertThat(iterationOrder(ADAPTER.preOrderTraversal(h))).isEqualTo("hdabcegf");
  }

  public void testPostOrder() {
    assertThat(iterationOrder(ADAPTER.postOrderTraversal(h))).isEqualTo("abcdefgh");
  }

  public void testBreadthOrder() {

  }

  @Test
  public void forGraph_depthFirstPreOrder_tree() throws Exception {
    Traverser<Character> traverser = Traverser.forGraph(TREE);

    assertEqualCharNodes(traverser.depthFirstPreOrder('h'), "hdabcegf");
    assertEqualCharNodes(traverser.depthFirstPreOrder('d'), "dabc");
    assertEqualCharNodes(traverser.depthFirstPreOrder('a'), "a");
  }

  @Test