Adjust copyrights years

<?php
/**
 * SeekQuarry/Yioop --
 * Open Source Pure PHP Search Engine, Crawler, and Indexer
 *
 * Copyright (C) 2009 - 2018  Chris Pollett chris@pollett.org
 *
 * LICENSE:
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * END LICENSE
 *
 * @author Chris Pollett chris@pollett.org
 * @license https://www.gnu.org/licenses/ GPL3
 * @link https://www.seekquarry.com/
 * @copyright 2009 - 2018
 * @filesource
 */
namespace seekquarry\yioop\tests;

use seekquarry\yioop\library\Trie;
use seekquarry\yioop\library\UnitTest;

/**
 * Used to test that the Trie class properly stores words that
 * could be used for an autosuggest dictionary
 *
 * @author Chris Pollett
 */
class TrieTest extends UnitTest
{
    /**
     * We'll set up one Trie for testing purpose
     */
    public function setUp()
    {
        $this->test_objects["TRIE"] = new Trie();
    }
    /**
     * Since a Trie is not a PersistentStructure we don't need to do
     * anything to tear it down
     */
    public function tearDown()
    {
    }
    /**
     * Check if we add something into our Trie, add returns the correct
     * sub-tree or false if does not exists
     */
    public function addTestCase()
    {
        $this->assertNotEqual(
            $this->test_objects['TRIE']->add(
                "hello"), false, "Successful add should not return false");
        $this->assertEqual(serialize($this->test_objects['TRIE']->add(
                "hell")), serialize(["o" => [" " => null], " " => null]),
                "Add subsequence of an existing string should return subtree");
    }
    /**
     * Check if we look up something in our Trie, that correct subtree
     * is returned or false if does not exists
     */
    public function existsTestCase()
    {
        $this->test_objects['TRIE']->add("hello");
        $this->test_objects['TRIE']->add("hell");
        $this->assertEqual(serialize($this->test_objects['TRIE']->exists(
                "hell")), serialize(["o" => [" " => null], " " => null]),
                "Exists should return correct subtree");
        $this->assertFalse($this->test_objects['TRIE']->exists(
                "helmut"), "If not in Trie should get false");
    }
    /**
     * Check that if we can get all the terms from a trie that begin
     * with a given prefix
     */
    public function getValuesTestCase()
    {
        $this->test_objects['TRIE']->add("hello");
        $this->test_objects['TRIE']->add("hell");
        $this->test_objects['TRIE']->add("helmut");
        $this->test_objects['TRIE']->add("handsome");
        $this->test_objects['TRIE']->add("hen");
        $this->assertEqual($this->test_objects['TRIE']->getValues("h", 5),
            ["hello", "hell", "helmut", "hen", "handsome"],
            "Returns first all in subtree");
    }
}