assertEqualCharNodes(traverser.breadthFirst('d'), "dabc");
    assertEqualCharNodes(traverser.breadthFirst('a'), "a");
  }

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

    assertEqualCharNodes(traverser.breadthFirst(charactersOf("hg")), "hgdefabc");

            assertNull(getIdMethod.invoke(crawlingConfigHelper, "W"));
            assertEquals("123", getIdMethod.invoke(crawlingConfigHelper, "W123"));
            assertEquals("abc", getIdMethod.invoke(crawlingConfigHelper, "Fabc"));
            assertEquals("xyz", getIdMethod.invoke(crawlingConfigHelper, "Dxyz"));
        } catch (Exception e) {
            fail("Failed to test getId method: " + e.getMessage());
        }
    }