% -*- texinfo -*-
% @deftypefn {Function File} {} fail (@var{code},@var{pattern})
% @deftypefnx {Function File} {} fail (@var{code},'warning',@var{pattern})
%
% Return true if @var{code} fails with an error message matching
% @var{pattern}, otherwise produce an error. Note that @var{code}
% is a string and if @var{code} runs successfully, the error produced is:
%
% @example
% expected error but got none
% @end example
%
% If the code fails with a different error, the message produced is:
%
% @example
% @group
% expected <pattern>
% but got <text of actual error>
% @end group
% @end example
%
% The angle brackets are not part of the output.
%
% Called with three arguments, the behavior is similar to
% @code{fail(@var{code}, @var{pattern})}, but produces an error if no
% warning is given during code execution or if the code fails.
%
% @end deftypefn