public function testDeleteIndexes()
 {
     $idx = $this->object->db->selectCollection('system.indexes');
     $this->object->ensureIndex((object) array('foo' => 1));
     $this->object->ensureIndex((object) array('foo' => -1));
     $this->object->ensureIndex((object) array('bar' => 1, 'baz' => -1));
     $num = iterator_count($idx->find((object) array('ns' => 'phpunit.c')));
     $this->assertEquals($num, 4);
     $this->object->deleteIndexes();
     $num = iterator_count($idx->find((object) array('ns' => 'phpunit.c')));
     $this->assertEquals($num, 1);
 }