From 6debd769393c9c5cdd4feb2a0c74bda173a13b1e Mon Sep 17 00:00:00 2001
From: Michael Foord <michael@voidspace.org.uk>
Date: Tue, 29 Jan 2013 23:07:57 +0000
Subject: Closes issue 15505. unittest.installHandler and non-callable signal
 handlers.

---
 Lib/unittest/signals.py         | 16 +++++++++++++++-
 Lib/unittest/test/test_break.py | 32 ++++++++++++++++++++++++++++++++
 Misc/NEWS                       |  3 +++
 3 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/Lib/unittest/signals.py b/Lib/unittest/signals.py
index fc31043..e6a5fc5 100644
--- a/Lib/unittest/signals.py
+++ b/Lib/unittest/signals.py
@@ -9,6 +9,20 @@ __unittest = True
 class _InterruptHandler(object):
     def __init__(self, default_handler):
         self.called = False
+        self.original_handler = default_handler
+        if isinstance(default_handler, int):
+            if default_handler == signal.SIG_DFL:
+                # Pretend it's signal.default_int_handler instead.
+                default_handler = signal.default_int_handler
+            elif default_handler == signal.SIG_IGN:
+                # Not quite the same thing as SIG_IGN, but the closest we
+                # can make it: do nothing.
+                def default_handler(unused_signum, unused_frame):
+                    pass
+            else:
+                raise TypeError("expected SIGINT signal handler to be "
+                                "signal.SIG_IGN, signal.SIG_DFL, or a "
+                                "callable object")
         self.default_handler = default_handler
 
     def __call__(self, signum, frame):
@@ -54,4 +68,4 @@ def removeHandler(method=None):
 
     global _interrupt_handler
     if _interrupt_handler is not None:
-        signal.signal(signal.SIGINT, _interrupt_handler.default_handler)
+        signal.signal(signal.SIGINT, _interrupt_handler.original_handler)
diff --git a/Lib/unittest/test/test_break.py b/Lib/unittest/test/test_break.py
index 77ce201..75532f4 100644
--- a/Lib/unittest/test/test_break.py
+++ b/Lib/unittest/test/test_break.py
@@ -13,9 +13,12 @@ import unittest
 @unittest.skipIf(sys.platform == 'freebsd6', "Test kills regrtest on freebsd6 "
     "if threads have been used")
 class TestBreak(unittest.TestCase):
+    int_handler = None
 
     def setUp(self):
         self._default_handler = signal.getsignal(signal.SIGINT)
+        if self.int_handler is not None:
+            signal.signal(signal.SIGINT, self.int_handler)
 
     def tearDown(self):
         signal.signal(signal.SIGINT, self._default_handler)
@@ -72,6 +75,10 @@ class TestBreak(unittest.TestCase):
 
 
     def testSecondInterrupt(self):
+        # Can't use skipIf decorator because the signal handler may have
+        # been changed after defining this method.
+        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
+            self.skipTest("test requires SIGINT to not be ignored")
         result = unittest.TestResult()
         unittest.installHandler()
         unittest.registerResult(result)
@@ -121,6 +128,10 @@ class TestBreak(unittest.TestCase):
 
 
     def testHandlerReplacedButCalled(self):
+        # Can't use skipIf decorator because the signal handler may have
+        # been changed after defining this method.
+        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
+            self.skipTest("test requires SIGINT to not be ignored")
         # If our handler has been replaced (is no longer installed) but is
         # called by the *new* handler, then it isn't safe to delay the
         # SIGINT and we should immediately delegate to the default handler
@@ -250,3 +261,24 @@ class TestBreak(unittest.TestCase):
 
         test()
         self.assertNotEqual(signal.getsignal(signal.SIGINT), default_handler)
+
+@unittest.skipUnless(hasattr(os, 'kill'), "Test requires os.kill")
+@unittest.skipIf(sys.platform =="win32", "Test cannot run on Windows")
+@unittest.skipIf(sys.platform == 'freebsd6', "Test kills regrtest on freebsd6 "
+    "if threads have been used")
+class TestBreakDefaultIntHandler(TestBreak):
+    int_handler = signal.default_int_handler
+
+@unittest.skipUnless(hasattr(os, 'kill'), "Test requires os.kill")
+@unittest.skipIf(sys.platform =="win32", "Test cannot run on Windows")
+@unittest.skipIf(sys.platform == 'freebsd6', "Test kills regrtest on freebsd6 "
+    "if threads have been used")
+class TestBreakSignalIgnored(TestBreak):
+    int_handler = signal.SIG_IGN
+
+@unittest.skipUnless(hasattr(os, 'kill'), "Test requires os.kill")
+@unittest.skipIf(sys.platform =="win32", "Test cannot run on Windows")
+@unittest.skipIf(sys.platform == 'freebsd6', "Test kills regrtest on freebsd6 "
+    "if threads have been used")
+class TestBreakSignalDefault(TestBreak):
+    int_handler = signal.SIG_DFL
diff --git a/Misc/NEWS b/Misc/NEWS
index 7ebe3f8..e9cd8c7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -216,6 +216,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #15505: `unittest.installHandler` no longer assumes SIGINT handler is
+  set to a callable object.
+
 - Issue #12004: Fix an internal error in PyZipFile when writing an invalid
   Python file.  Patch by Ben Morgan.
 
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