/**
* Tests if CacheKeyException will be thrown, when using Cache::flushCache and
* key is not a string
*
* @expectedException \NumPHP\Core\Exception\CacheKeyException
* @expectedExceptionMessage Key has to be a string
*/
public function testFlushCacheForbiddenKey()
{
$numArray = new NumArray(6);
$numArray->flushCache(6);
}