public List<String> all() {
        char[] chars = new char[MAX_CHAR_LENGTH];
        List<String> value = depth(this.root, new ArrayList<String>(), chars, 0);
        return value;
    }
@Test
    public void all() throws Exception {
        TrieTree trieTree = new TrieTree();
        trieTree.insert("ABC");
        trieTree.insert("abC");
        List<String> all = trieTree.all();
        String result = "";
        for (String s : all) {
            result += s + ",";
            System.out.println(s);
        }

        Assert.assertTrue("ABC,abC,".equals(result));

    }