anchor.diff:  %%-------------------------------------------------------------------
   -spec verify_storage_internal(helpers:helper(), helpers:user_ctx(), [node()],
       helpers:file_id(), Content :: binary()) ->
  -    {ok, {helpers:file_id(), binary()}} | {error, term()}.
  +    {ok, {helpers:file_id(), binary()}} |
  +    {error, term()} | {error, term(), Stacktrace :: list()}.
   verify_storage_internal(_Helper, _AdminCtx, [], FileId, FileContent) ->
       {ok, {FileId, FileContent}};
   verify_storage_internal(Helper, AdminCtx, [Node | Nodes], FileId, ExpectedFileContent) ->
       case verify_test_file(Node, Helper, AdminCtx, FileId, ExpectedFileContent) of
           ok ->
               FileId2 = generate_file_id(),
  -            FileContent = create_test_file(Node, Helper, AdminCtx, FileId),
  -            verify_storage_internal(Helper, AdminCtx, Nodes, FileId2, FileContent);
  +            case create_test_file(Node, Helper, AdminCtx, FileId) of
  +                {ok, FileContent} ->
  +                    verify_storage_internal(Helper, AdminCtx,
  +                        Nodes, FileId2, FileContent);
  +                Error -> Error
  +            end;
           Error ->
               Error
       end.
   
   -spec create_test_file(node(), helpers:helper(), helpers:user_ctx(), helpers:file_id()) ->
  -    Content :: binary().
  +    {ok, Content :: binary()} | {error, Reason :: term(), Stacktrace :: list()}.
   create_test_file(Node, Helper, UserCtx, FileId) ->
  -    rpc:call(Node, ?MODULE, create_test_file, [Helper, UserCtx, FileId]).
  +    case rpc:call(Node, ?MODULE, create_test_file, [Helper, UserCtx, FileId]) of
  +        {badrpc, {'EXIT', {Reason, Stacktrace}}} ->
  +            ?ERR_STORAGE_TEST_FILE_CREATE(Node, Reason, Stacktrace);
  +        <<Content/binary>> ->
  +            {ok, Content}
  +    end.
   
   -spec verify_test_file(node(), helpers:helper(), helpers:user_ctx(),
  -    helpers:file_id(), Content :: binary()) -> ok | {error, term()}.
  +    helpers:file_id(), Content :: binary()) ->
  +    ok | {error, term()} | {error, term(), Stacktrace :: list()}.
   verify_test_file(Node, Helper, UserCtx, FileId, ExpectedFileContent) ->
  -    rpc:call(Node, ?MODULE, verify_test_file, [Helper, UserCtx, FileId, ExpectedFileContent]).+    case rpc:call(Node, ?MODULE, verify_test_file,
  +        [Helper, UserCtx, FileId, ExpectedFileContent]) of
  +        {badrpc, {'EXIT', {Reason, Stacktrace}}} ->
  +            ?ERR_STORAGE_TEST_FILE_READ(Node, Reason, Stacktrace);
  +        Result ->
  +            Result
  +    end.
  
positive.code: 
  %% API
  -export([generate_file_id/0, create_test_file/3, read_test_file/3,
      update_test_file/3, remove_test_file/4, verify_storage_on_all_nodes/1]).
  
  %% exported for RPC
  -export([verify_test_file/4]).
  
negative.code: -spec verify_test_file(helpers:helper(), helpers:user_ctx(), helpers:file_id(),
      Content :: binary()) -> ok | {error, term()}.
  verify_test_file(Helper, UserCtx, FileId, ExpectedFileContent) ->
      try
          case read_test_file(Helper, UserCtx, FileId) of
              ExpectedFileContent ->
                  ok;
              UnexpectedFileContent ->
                  ?error("Unexpected test file content in ~tp", [FileId]),
                  ?ERR_STORAGE_TEST_FILE_READ(node(),
                      {invalid_content, ExpectedFileContent, UnexpectedFileContent})
          end
      after
          remove_test_file(Helper, UserCtx, FileId, byte_size(ExpectedFileContent))
      end.
  
  %%%===================================================================
  