From 009220eae2e6b456707c1c89ef3f344b682e89d5 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Tue, 12 Feb 2019 10:54:31 -0800
Subject: [PATCH] bpo-35505: Skip test_imap4_host_default_value if localhost
 listens on IMAP port (GH-11823)
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Make test_imap4_host_default_value independent on whether the
local IMAP server is running.
(cherry picked from commit 3dc67d0316740e78e7cd014343f34d85908219b7)

Co-authored-by: Matěj Cepl <mcepl@cepl.eu>
---
 Lib/test/test_imaplib.py                               | 10 ++++++++++
 .../Tests/2019-02-12-01-33-08.bpo-35505.N9ba_K.rst     |  2 ++
 2 files changed, 12 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Tests/2019-02-12-01-33-08.bpo-35505.N9ba_K.rst

diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index a0b598d0c78..a060143e1f6 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -8,6 +8,7 @@ import socketserver
 import time
 import calendar
 import threading
+import socket
 
 from test.support import (reap_threads, verbose, transient_internet,
                           run_with_tz, run_with_locale, cpython_only)
@@ -71,6 +72,15 @@ class TestImaplib(unittest.TestCase):
             imaplib.Time2Internaldate(t)
 
     def test_imap4_host_default_value(self):
+        # Check whether the IMAP4_PORT is truly unavailable.
+        with socket.socket() as s:
+            try:
+                s.connect(('', imaplib.IMAP4_PORT))
+                self.skipTest(
+                    "Cannot run the test with local IMAP server running.")
+            except socket.error:
+                pass
+
         expected_errnos = [
             # This is the exception that should be raised.
             errno.ECONNREFUSED,
diff --git a/Misc/NEWS.d/next/Tests/2019-02-12-01-33-08.bpo-35505.N9ba_K.rst b/Misc/NEWS.d/next/Tests/2019-02-12-01-33-08.bpo-35505.N9ba_K.rst
new file mode 100644
index 00000000000..f1d48d61207
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2019-02-12-01-33-08.bpo-35505.N9ba_K.rst
@@ -0,0 +1,2 @@
+Make test_imap4_host_default_value independent on whether the 
+local IMAP server is running.