[Python-checkins] [3.6] bpo-31158: Fix nondeterministic read in test_pty (GH-3808) (GH-3852)
Victor Stinner
webhook-mailer at python.org
Mon Oct 2 05:57:59 EDT 2017
https://github.com/python/cpython/commit/66fb5ef3bb9e36187a0e5052dfd99899447df671
commit: 66fb5ef3bb9e36187a0e5052dfd99899447df671
branch: 3.6
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: Victor Stinner <victor.stinner at gmail.com>
date: 2017-10-02T02:57:56-07:00
summary:
[3.6] bpo-31158: Fix nondeterministic read in test_pty (GH-3808) (GH-3852)
(cherry picked from commit e6f62f69f07892b993910ff03c9db3ffa5cb9ca5)
files:
M Lib/test/test_pty.py
diff --git a/Lib/test/test_pty.py b/Lib/test/test_pty.py
index 15f88e4fcd7..45ebea51a05 100644
--- a/Lib/test/test_pty.py
+++ b/Lib/test/test_pty.py
@@ -10,6 +10,7 @@
import select
import signal
import socket
+import io # readline
import unittest
TEST_STRING_1 = b"I wish to buy a fish license.\n"
@@ -23,6 +24,16 @@ def debug(msg):
pass
+# Note that os.read() is nondeterministic so we need to be very careful
+# to make the test suite deterministic. A normal call to os.read() may
+# give us less than expected.
+#
+# Beware, on my Linux system, if I put 'foo\n' into a terminal fd, I get
+# back 'foo\r\n' at the other end. The behavior depends on the termios
+# setting. The newline translation may be OS-specific. To make the
+# test suite deterministic and OS-independent, the functions _readline
+# and normalize_output can be used.
+
def normalize_output(data):
# Some operating systems do conversions on newline. We could possibly
# fix that by doing the appropriate termios.tcsetattr()s. I couldn't
@@ -44,6 +55,12 @@ def normalize_output(data):
return data
+def _readline(fd):
+ """Read one line. May block forever if no newline is read."""
+ reader = io.FileIO(fd, mode='rb', closefd=False)
+ return reader.readline()
+
+
# Marginal testing of pty suite. Cannot do extensive 'do or fail' testing
# because pty code is not too portable.
@@ -98,14 +115,14 @@ def test_basic(self):
debug("Writing to slave_fd")
os.write(slave_fd, TEST_STRING_1)
- s1 = os.read(master_fd, 1024)
+ s1 = _readline(master_fd)
self.assertEqual(b'I wish to buy a fish license.\n',
normalize_output(s1))
debug("Writing chunked output")
os.write(slave_fd, TEST_STRING_2[:5])
os.write(slave_fd, TEST_STRING_2[5:])
- s2 = os.read(master_fd, 1024)
+ s2 = _readline(master_fd)
self.assertEqual(b'For my pet fish, Eric.\n', normalize_output(s2))
os.close(slave_fd)
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