Function TEST_F

3rdparty/libprocess/src/tests/subprocess_tests.cpp:79–138

Calls subprocess, pipes output to an open file descriptor (and specifically a file descriptor for a file, rather than a socket).

// Calls subprocess, pipes output to an open file descriptor (and specifically
// a file descriptor for a file, rather than a socket).
TEST_F(SubprocessTest, PipeOutputToFileDescriptor)
{
  // Create temporary files to pipe `stdin` to, and open it. We will pipe
  // output into this file.
  const string outfile_name = "out.txt";
  const string outfile = path::join(sandbox.get(), outfile_name);
  ASSERT_SOME(os::touch(outfile));

  Try<int_fd> outfile_fd = os::open(outfile, O_RDWR);
  ASSERT_SOME(outfile_fd);

  // Create temporary files to pipe `stderr` to, and open it. We will pipe
  // error into this file.
  const string errorfile_name = "error.txt";
  const string errorfile = path::join(sandbox.get(), errorfile_name);
  ASSERT_SOME(os::touch(errorfile));

  Try<int_fd> errorfile_fd = os::open(errorfile, O_RDWR);
  ASSERT_SOME(errorfile_fd);

  // RAII handle for the file descriptor increases chance that we clean up
  // after ourselves.
  const auto close_fd = [](int_fd* fd) { os::close(*fd); };

  shared_ptr<int_fd> safe_out_fd(&outfile_fd.get(), close_fd);
  shared_ptr<int_fd> safe_err_fd(&errorfile_fd.get(), close_fd);

  // Pipe simple string to output file.
  run_subprocess(
    [outfile_fd]() -> Try<Subprocess> {
      return subprocess(
          "echo hello",
          Subprocess::FD(STDIN_FILENO),
          Subprocess::FD(outfile_fd.get()),
          Subprocess::FD(STDERR_FILENO));
    });

  // Pipe simple string to error file.
  run_subprocess(
    [errorfile_fd]() -> Try<Subprocess> {
      return subprocess(
          "echo goodbye 1>&2",
          Subprocess::FD(STDIN_FILENO),
          Subprocess::FD(STDOUT_FILENO),
          Subprocess::FD(errorfile_fd.get()));
    });

  // Finally, read output and error files, and make sure messages are inside.
  const Result<string> output = os::read(outfile);
  ASSERT_SOME(output);
  EXPECT_EQ("hello\n", output.get());

  const Result<string> error = os::read(errorfile);
  ASSERT_SOME(error);
#ifdef __WINDOWS__
  EXPECT_EQ("goodbye \n", error.get());
#else
  EXPECT_EQ("goodbye\n", error.get());