public function test_transform_query_nonexistent_terms()
 {
     $tq = new WP_Tax_Query(array(array('terms' => array('foo'), 'field' => 'slug', 'operator' => 'AND')));
     $tq->transform_query($tq->queries[0], 'term_taxonomy_id');
     $this->assertTrue(is_wp_error($tq->queries[0]));
 }