bpo-28684: asyncio tests handle PermissionError raised on binding unix sockets (GH-4503)

The test.support.skip_unless_bind_unix_socket() decorator is used to skip
asyncio tests that fail because the platform lacks a functional bind()
function for unix domain sockets (as it is the case for non root users on the
recent Android versions that run now SELinux in enforcing mode).

4 files changed, 40 insertions, 11 deletions

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index b7cbdc6..e864896 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -88,6 +88,7 @@ __all__ = [
     "requires_IEEE_754", "skip_unless_xattr", "requires_zlib",
     "anticipate_failure", "load_package_tests", "detect_api_mismatch",
     "check__all__", "requires_android_level", "requires_multiprocessing_queue",
+    "skip_unless_bind_unix_socket",
     # sys
     "is_jython", "is_android", "check_impl_detail", "unix_shell",
     "setswitchinterval",
@@ -2432,6 +2433,28 @@ def skip_unless_xattr(test):
     msg = "no non-broken extended attribute support"
     return test if ok else unittest.skip(msg)(test)
 
+_bind_nix_socket_error = None
+def skip_unless_bind_unix_socket(test):
+    """Decorator for tests requiring a functional bind() for unix sockets."""
+    if not hasattr(socket, 'AF_UNIX'):
+        return unittest.skip('No UNIX Sockets')(test)
+    global _bind_nix_socket_error
+    if _bind_nix_socket_error is None:
+        path = TESTFN + "can_bind_unix_socket"
+        with socket.socket(socket.AF_UNIX) as sock:
+            try:
+                sock.bind(path)
+                _bind_nix_socket_error = False
+            except OSError as e:
+                _bind_nix_socket_error = e
+            finally:
+                unlink(path)
+    if _bind_nix_socket_error:
+        msg = 'Requires a functional unix bind(): %s' % _bind_nix_socket_error
+        return unittest.skip(msg)(test)
+    else:
+        return test
+
 
 def fs_is_case_insensitive(directory):
     """Detects if the file system for the specified directory is case-insensitive."""
diff --git a/Lib/test/test_asyncio/test_events.py b/Lib/test/test_asyncio/test_events.py
index 1a8bc13..78b30b9 100644
--- a/Lib/test/test_asyncio/test_events.py
+++ b/Lib/test/test_asyncio/test_events.py
@@ -22,6 +22,7 @@ import errno
 import unittest
 from unittest import mock
 import weakref
+from test import support
 
 if sys.platform != 'win32':
     import tty
@@ -470,7 +471,7 @@ class EventLoopTestsMixin:
             sock = socket.socket()
             self._basetest_sock_recv_into(httpd, sock)
 
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    @support.skip_unless_bind_unix_socket
     def test_unix_sock_client_ops(self):
         with test_utils.run_test_unix_server() as httpd:
             sock = socket.socket(socket.AF_UNIX)
@@ -606,7 +607,7 @@ class EventLoopTestsMixin:
                 lambda: MyProto(loop=self.loop), *httpd.address)
             self._basetest_create_connection(conn_fut)
 
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    @support.skip_unless_bind_unix_socket
     def test_create_unix_connection(self):
         # Issue #20682: On Mac OS X Tiger, getsockname() returns a
         # zero-length address for UNIX socket.
@@ -736,8 +737,8 @@ class EventLoopTestsMixin:
             self._test_create_ssl_connection(httpd, create_connection,
                                              peername=httpd.address)
 
+    @support.skip_unless_bind_unix_socket
     @unittest.skipIf(ssl is None, 'No ssl module')
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
     def test_create_ssl_unix_connection(self):
         # Issue #20682: On Mac OS X Tiger, getsockname() returns a
         # zero-length address for UNIX socket.
@@ -961,7 +962,7 @@ class EventLoopTestsMixin:
 
         return server, path
 
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    @support.skip_unless_bind_unix_socket
     def test_create_unix_server(self):
         proto = MyProto(loop=self.loop)
         server, path = self._make_unix_server(lambda: proto)
@@ -1053,8 +1054,8 @@ class EventLoopTestsMixin:
         # stop serving
         server.close()
 
+    @support.skip_unless_bind_unix_socket
     @unittest.skipIf(ssl is None, 'No ssl module')
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
     def test_create_unix_server_ssl(self):
         proto = MyProto(loop=self.loop)
         server, path = self._make_ssl_unix_server(
@@ -1113,8 +1114,8 @@ class EventLoopTestsMixin:
         self.assertIsNone(proto.transport)
         server.close()
 
+    @support.skip_unless_bind_unix_socket
     @unittest.skipIf(ssl is None, 'No ssl module')
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
     def test_create_unix_server_ssl_verify_failed(self):
         proto = MyProto(loop=self.loop)
         server, path = self._make_ssl_unix_server(
@@ -1171,8 +1172,8 @@ class EventLoopTestsMixin:
         proto.transport.close()
         server.close()
 
+    @support.skip_unless_bind_unix_socket
     @unittest.skipIf(ssl is None, 'No ssl module')
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
     def test_create_unix_server_ssl_verified(self):
         proto = MyProto(loop=self.loop)
         server, path = self._make_ssl_unix_server(
diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
index 6d16d20..a1e5bd7 100644
--- a/Lib/test/test_asyncio/test_streams.py
+++ b/Lib/test/test_asyncio/test_streams.py
@@ -9,6 +9,7 @@ import sys
 import threading
 import unittest
 from unittest import mock
+from test import support
 try:
     import ssl
 except ImportError:
@@ -57,7 +58,7 @@ class StreamReaderTests(test_utils.TestCase):
                                                loop=self.loop)
             self._basetest_open_connection(conn_fut)
 
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    @support.skip_unless_bind_unix_socket
     def test_open_unix_connection(self):
         with test_utils.run_test_unix_server() as httpd:
             conn_fut = asyncio.open_unix_connection(httpd.address,
@@ -86,8 +87,8 @@ class StreamReaderTests(test_utils.TestCase):
 
             self._basetest_open_connection_no_loop_ssl(conn_fut)
 
+    @support.skip_unless_bind_unix_socket
     @unittest.skipIf(ssl is None, 'No ssl module')
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
     def test_open_unix_connection_no_loop_ssl(self):
         with test_utils.run_test_unix_server(use_ssl=True) as httpd:
             conn_fut = asyncio.open_unix_connection(
@@ -113,7 +114,7 @@ class StreamReaderTests(test_utils.TestCase):
                                                loop=self.loop)
             self._basetest_open_connection_error(conn_fut)
 
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    @support.skip_unless_bind_unix_socket
     def test_open_unix_connection_error(self):
         with test_utils.run_test_unix_server() as httpd:
             conn_fut = asyncio.open_unix_connection(httpd.address,
@@ -634,7 +635,7 @@ class StreamReaderTests(test_utils.TestCase):
         server.stop()
         self.assertEqual(msg, b"hello world!\n")
 
-    @unittest.skipUnless(hasattr(socket, 'AF_UNIX'), 'No UNIX Sockets')
+    @support.skip_unless_bind_unix_socket
     def test_start_unix_server(self):
 
         class MyServer:
diff --git a/Lib/test/test_asyncio/test_unix_events.py b/Lib/test/test_asyncio/test_unix_events.py
index fe758ba..04284fa 100644
--- a/Lib/test/test_asyncio/test_unix_events.py
+++ b/Lib/test/test_asyncio/test_unix_events.py
@@ -13,6 +13,7 @@ import tempfile
 import threading
 import unittest
 from unittest import mock
+from test import support
 
 if sys.platform == 'win32':
     raise unittest.SkipTest('UNIX only')
@@ -239,6 +240,7 @@ class SelectorEventLoopUnixSocketTests(test_utils.TestCase):
         self.loop = asyncio.SelectorEventLoop()
         self.set_event_loop(self.loop)
 
+    @support.skip_unless_bind_unix_socket
     def test_create_unix_server_existing_path_sock(self):
         with test_utils.unix_socket_path() as path:
             sock = socket.socket(socket.AF_UNIX)
@@ -251,6 +253,7 @@ class SelectorEventLoopUnixSocketTests(test_utils.TestCase):
             srv.close()
             self.loop.run_until_complete(srv.wait_closed())
 
+    @support.skip_unless_bind_unix_socket
     def test_create_unix_server_pathlib(self):
         with test_utils.unix_socket_path() as path:
             path = pathlib.Path(path)
@@ -308,6 +311,7 @@ class SelectorEventLoopUnixSocketTests(test_utils.TestCase):
 
     @unittest.skipUnless(hasattr(socket, 'SOCK_NONBLOCK'),
                          'no socket.SOCK_NONBLOCK (linux only)')
+    @support.skip_unless_bind_unix_socket
     def test_create_unix_server_path_stream_bittype(self):
         sock = socket.socket(
             socket.AF_UNIX, socket.SOCK_STREAM | socket.SOCK_NONBLOCK)