public function testDeleteIndex() {
      $idx = $this->object->db->selectCollection('system.indexes');

      $this->object->ensureIndex('foo');
      $this->object->ensureIndex((object)array('foo' => -1));

      $num = iterator_count($idx->find((object)array('ns' => 'phpunit.c')));
      $this->assertEquals($num, 3);

      $this->object->deleteIndex(null);
      $num = iterator_count($idx->find((object)array('ns' => 'phpunit.c')));
      $this->assertEquals($num, 3);

      $this->object->deleteIndex((object)array('foo' => 1));
      $num = iterator_count($idx->find((object)array('ns' => 'phpunit.c')));
      $this->assertEquals($num, 2);

      $this->object->deleteIndex('foo');
      $num = iterator_count($idx->find((object)array('ns' => 'phpunit.c')));
      $this->assertEquals($num, 2);

      $this->object->deleteIndex((object)array('foo' => -1));
      $num = iterator_count($idx->find((object)array('ns' => 'phpunit.c')));
      $this->assertEquals($num, 1);
    }