bpo-34587, test_socket: remove RDSTest.testCongestion() (GH-9277)

The test tries to fill the receiver's socket buffer and expects an
error. But the RDS protocol doesn't require that. Moreover, the Linux
implementation of RDS expects that the producer of the messages
reduces its rate, it's not the role of the receiver to trigger an
error.

The test fails on Fedora 28 by design, so remove it.
(cherry picked from commit 7484bdfd1e2e33fdd2c44dd4ffa044aacd495337)

Co-authored-by: Victor Stinner <vstinner@redhat.com>

2 files changed, 5 insertions, 27 deletions

diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 4f3c477..f4d58eb 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -2054,33 +2054,6 @@ class RDSTest(ThreadedRDSSocketTest):
         self.data = b'select'
         self.cli.sendto(self.data, 0, (HOST, self.port))
 
-    def testCongestion(self):
-        # wait until the sender is done
-        self.evt.wait()
-
-    def _testCongestion(self):
-        # test the behavior in case of congestion
-        self.data = b'fill'
-        self.cli.setblocking(False)
-        try:
-            # try to lower the receiver's socket buffer size
-            self.cli.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 16384)
-        except OSError:
-            pass
-        with self.assertRaises(OSError) as cm:
-            try:
-                # fill the receiver's socket buffer
-                while True:
-                    self.cli.sendto(self.data, 0, (HOST, self.port))
-            finally:
-                # signal the receiver we're done
-                self.evt.set()
-        # sendto() should have failed with ENOBUFS
-        self.assertEqual(cm.exception.errno, errno.ENOBUFS)
-        # and we should have received a congestion notification through poll
-        r, w, x = select.select([self.serv], [], [], 3.0)
-        self.assertIn(self.serv, r)
-
 
 @unittest.skipIf(fcntl is None, "need fcntl")
 @unittest.skipUnless(HAVE_SOCKET_VSOCK,
diff --git a/Misc/NEWS.d/next/Tests/2018-09-13-20-58-07.bpo-34587.rCcxp3.rst b/Misc/NEWS.d/next/Tests/2018-09-13-20-58-07.bpo-34587.rCcxp3.rst
new file mode 100644
index 0000000..8d45418
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2018-09-13-20-58-07.bpo-34587.rCcxp3.rst
@@ -0,0 +1,5 @@
+test_socket: Remove RDSTest.testCongestion(). The test tries to fill the
+receiver's socket buffer and expects an error. But the RDS protocol doesn't
+require that. Moreover, the Linux implementation of RDS expects that the
+producer of the messages reduces its rate, it's not the role of the receiver to
+trigger an error. The test fails on Fedora 28 by design, so just remove it.