From c73953d94aa391a4170691c8e85fa8a123b24221 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Tue, 14 Apr 2020 08:40:48 -0400
Subject: [PATCH 1/5] Capture and report Foolscap Tub Listener creation stack
 on error

---
 src/allmydata/test/__init__.py | 38 ++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/src/allmydata/test/__init__.py b/src/allmydata/test/__init__.py
index 804d37935..af55be353 100644
--- a/src/allmydata/test/__init__.py
+++ b/src/allmydata/test/__init__.py
@@ -52,6 +52,44 @@ def _configure_hypothesis():
     settings.load_profile(profile_name)
 _configure_hypothesis()
 
+def logging_for_pb_listener():
+    """
+    Make Foolscap listen error reports include Listener creation stack
+    information.
+    """
+    from traceback import extract_stack, format_list
+    from foolscap.pb import Listener
+    from twisted.python.log import err
+    from twisted.application import service
+
+    original__init__ = Listener.__init__
+    def _listener__init__(self, *a, **kw):
+        original__init__(self, *a, **kw)
+        # Capture the stack here, where Listener is instantiated.  This is
+        # likely to explain what code is responsible for this Listener, useful
+        # information to have when the Listener eventually fails to listen.
+        self._creation_stack = extract_stack()
+
+    # Override the Foolscap implementation with one that has an errback
+    def _listener_startService(self):
+        service.Service.startService(self)
+        d = self._ep.listen(self)
+        def _listening(lp):
+            self._lp = lp
+        d.addCallbacks(
+            _listening,
+            # Make sure that this listen failure is reported promptly and with
+            # the creation stack.
+            err,
+            errbackArgs=(
+                "Listener created at {}".format(
+                    "".join(format_list(self._creation_stack)),
+                ),
+            ),
+        )
+    Listener.__init__ = _listener__init__
+    Listener.startService = _listener_startService
+logging_for_pb_listener()
 
 import sys
 if sys.platform == "win32":

From 47bef6038f8213fde691a4b9e8ee7861d9747fd5 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Tue, 14 Apr 2020 08:41:10 -0400
Subject: [PATCH 2/5] news fragment

---
 newsfragments/3302.minor | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 newsfragments/3302.minor

diff --git a/newsfragments/3302.minor b/newsfragments/3302.minor
new file mode 100644
index 000000000..e69de29bb

From 72ca4e8c53191aabe6599ac72c113106552f1b8f Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Wed, 15 Apr 2020 08:54:50 -0400
Subject: [PATCH 3/5] move the imports

---
 src/allmydata/test/__init__.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/allmydata/test/__init__.py b/src/allmydata/test/__init__.py
index af55be353..fb62e438f 100644
--- a/src/allmydata/test/__init__.py
+++ b/src/allmydata/test/__init__.py
@@ -1,3 +1,8 @@
+from traceback import extract_stack, format_list
+from foolscap.pb import Listener
+from twisted.python.log import err
+from twisted.application import service
+
 
 from foolscap.logging.incident import IncidentQualifier
 class NonQualifier(IncidentQualifier, object):
@@ -57,11 +62,6 @@ def logging_for_pb_listener():
     Make Foolscap listen error reports include Listener creation stack
     information.
     """
-    from traceback import extract_stack, format_list
-    from foolscap.pb import Listener
-    from twisted.python.log import err
-    from twisted.application import service
-
     original__init__ = Listener.__init__
     def _listener__init__(self, *a, **kw):
         original__init__(self, *a, **kw)

From d4d8ce4e13d6f5b9103c18c1da722fe26f0f0bde Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Wed, 15 Apr 2020 08:55:00 -0400
Subject: [PATCH 4/5] missing front matter

---
 src/allmydata/test/__init__.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/allmydata/test/__init__.py b/src/allmydata/test/__init__.py
index fb62e438f..60d9b87d6 100644
--- a/src/allmydata/test/__init__.py
+++ b/src/allmydata/test/__init__.py
@@ -1,3 +1,18 @@
+# Tahoe-LAFS -- secure, distributed storage grid
+#
+# Copyright © 2020 The Tahoe-LAFS Software Foundation
+#
+# This file is part of Tahoe-LAFS.
+#
+# See the docs/about.rst file for licensing information.
+
+"""
+Some setup that should apply across the entire test suite.
+
+Rather than defining interesting APIs for other code to use, this just causes
+some side-effects which make things better when the test suite runs.
+"""
+
 from traceback import extract_stack, format_list
 from foolscap.pb import Listener
 from twisted.python.log import err

From 71aa17ab0bbb3371f43c205aeda8092867c300b2 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Wed, 15 Apr 2020 09:07:23 -0400
Subject: [PATCH 5/5] I assume it's utf-8

---
 src/allmydata/test/__init__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/allmydata/test/__init__.py b/src/allmydata/test/__init__.py
index 60d9b87d6..abbde919f 100644
--- a/src/allmydata/test/__init__.py
+++ b/src/allmydata/test/__init__.py
@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 # Tahoe-LAFS -- secure, distributed storage grid
 #
 # Copyright © 2020 The Tahoe-LAFS Software Foundation