Issue #4705: Fix the -u ("unbuffered binary stdout and stderr") command-line
flag to work properly. Furthermore, when specifying -u, the text stdout
and stderr streams have line-by-line buffering enabled (the default being
to buffer arbitrary chunks of data). Patch by Victor Stinner, test by me.
diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index e8db7d0..e567184 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -142,6 +142,23 @@
self.exit_code('-c', command),
0)
+ def test_unbuffered_output(self):
+ # Test expected operation of the '-u' switch
+ for stream in ('stdout', 'stderr'):
+ # Binary is unbuffered
+ code = ("import os, sys; sys.%s.buffer.write(b'x'); os._exit(0)"
+ % stream)
+ data, rc = self.start_python_and_exit_code('-u', '-c', code)
+ self.assertEqual(rc, 0)
+ self.assertEqual(data, b'x', "binary %s not unbuffered" % stream)
+ # Text is line-buffered
+ code = ("import os, sys; sys.%s.write('x\\n'); os._exit(0)"
+ % stream)
+ data, rc = self.start_python_and_exit_code('-u', '-c', code)
+ self.assertEqual(rc, 0)
+ self.assertEqual(data.strip(), b'x',
+ "text %s not line-buffered" % stream)
+
def test_main():
test.support.run_unittest(CmdLineTest)