public function testSerialize()
 {
     $r = new Reporter();
     $r->name = 'KwangSeob Jeong';
     $r->emailAddress = '*****@*****.**';
     $r->avatarUrls = 'http://my.avatar.com/avatarUrls';
     $r->displayName = 'lesstif';
     $d = $r->toArray(['name', 'emailAddress'], $excludeMode = true);
     Dumper::dump($d);
     // serialized array have not 'name' and 'emailAddress' keys.
     $this->assertEquals(false, array_key_exists('name', $d), '"name" key is exists!.');
     $this->assertEquals(false, array_key_exists('emailAddress', $d));
     $d = $r->toArray(['name', 'emailAddress'], $excludeMode = false);
     // serialized array must have only 'name' and 'emailAddress' keys.
     $this->assertEquals(true, array_key_exists('name', $d), '"name" key is not exists!.');
     $this->assertEquals(true, array_key_exists('emailAddress', $d));
     $this->assertEquals(2, count($d));
     Dumper::dump($d);
 }