def _testPipeLoggerToPipe(self, test_string, loop=None): """ Test PipeLogger writing to a pipe connected to a PipeReader. This verifies that PipeLogger does not deadlock when writing to a pipe that's drained by a PipeReader running in the same process (requires non-blocking write). """ producer = PopenProcess(proc=subprocess.Popen( ["bash", "-c", self._echo_cmd % test_string], stdout=subprocess.PIPE, stderr=subprocess.STDOUT), scheduler=loop) pr, pw = os.pipe() consumer = producer.pipe_reader = PipeLogger( background=True, input_fd=producer.proc.stdout, log_file_path=os.fdopen(pw, 'wb', 0)) reader = _reader(pr, loop=loop) yield producer.async_start() content = yield reader yield producer.async_wait() yield consumer.async_wait() self.assertEqual(producer.returncode, os.EX_OK) self.assertEqual(consumer.returncode, os.EX_OK) coroutine_return(content.decode('ascii', 'replace'))