libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/flush.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // <ostream>
  10
  11 // template <class charT, class traits = char_traits<charT> >
  12 //   class basic_ostream;
  13
  14 // basic_ostream& flush();
  15
  16 #include <ostream>
  17 #include <cassert>
  18
  19 #include "test_macros.h"
  20
  21 int sync_called = 0;
  22
  23 template <class CharT>
  24 class testbuf
  25     : public std::basic_streambuf<CharT>
  26 {
  27 public:
  28     testbuf()
  29     {
  30     }
  31
  32 protected:
  33
  34     virtual int
  35         sync()
  36         {
  37             if (sync_called++ == 1)
  38                 return -1;
  39             return 0;
  40         }
  41 };
  42
  43 int main(int, char**)
  44 {
  45     {
  46         testbuf<char> sb;
  47         std::ostream os(&sb);
  48         os.flush();
  49         assert(os.good());
  50         assert(sync_called == 1);
  51         os.flush();
  52         assert(os.bad());
  53         assert(sync_called == 2);
  54     }
  55
  56   return 0;
  57 }