anchor.diff:      db_ops,
       basic_op,
       update_doc,
  +    delete_doc_without_revision,
       update_with,
       async_update,
       bad_doc,
  
positive.code:   db_ops/1,
    basic_op/1,
    update_doc/1,
    update_with/1,
    async_update/1,
    bad_doc/1,
  
negative.code:   {ok, <<"a">>, _RevId2} = barrel_httpc:delete(db(Config), <<"a">>, [{rev, RevId2}]),
    {error, not_found} = barrel_httpc:get(db(Config), <<"a">>, []),
    {ok, <<"a">>, _RevId3} = barrel_httpc:post(db(Config), Doc, []).
  
  
  delete_doc_without_revision(Config) ->
    Doc = #{ <<"id">> => <<"a">>, <<"v">> => 1},
    {error, not_found} = barrel_httpc:get(db(Config), <<"a">>, []),
    {ok, <<"a">>, RevId} = barrel_httpc:post(db(Config), Doc, []),
    {ok, Doc, _Meta} = barrel_httpc:get(db(Config), <<"a">>, []),
    {ok, _, _} = barrel_httpc:delete(db(Config), <<"a">>, []),
    {error, not_found} = barrel_httpc:get(db(Config), <<"a">>, []).
  
  update_with(Config) ->
    Doc = #{ <<"id">> => <<"a">>, <<"v">> => 1},
  