Use os.devnull instead of hardcoded '/dev/null'.

Lib/test/test_asyncio/test_unix_events.py

@@ -295,7 +295,7 @@ def test_create_unix_server_bind_error(self, m_socket):
 
     def test_create_unix_connection_path_sock(self):
         coro = self.loop.create_unix_connection(
-            lambda: None, '/dev/null', sock=object())
+            lambda: None, os.devnull, sock=object())
         with self.assertRaisesRegex(ValueError, 'path and sock can not be'):
             self.loop.run_until_complete(coro)
 
@@ -308,14 +308,14 @@ def test_create_unix_connection_nopath_nosock(self):
 
     def test_create_unix_connection_nossl_serverhost(self):
         coro = self.loop.create_unix_connection(
-            lambda: None, '/dev/null', server_hostname='spam')
+            lambda: None, os.devnull, server_hostname='spam')
         with self.assertRaisesRegex(ValueError,
                                     'server_hostname is only meaningful'):
             self.loop.run_until_complete(coro)
 
     def test_create_unix_connection_ssl_noserverhost(self):
         coro = self.loop.create_unix_connection(
-            lambda: None, '/dev/null', ssl=True)
+            lambda: None, os.devnull, ssl=True)
 
         with self.assertRaisesRegex(
             ValueError, 'you have to pass server_hostname when using ssl'):

Lib/test/test_bz2.py

@@ -87,11 +87,11 @@ def createTempFile(self, streams=1, suffix=b""):
 
     def testBadArgs(self):
         self.assertRaises(TypeError, BZ2File, 123.456)
-        self.assertRaises(ValueError, BZ2File, "/dev/null", "z")
-        self.assertRaises(ValueError, BZ2File, "/dev/null", "rx")
-        self.assertRaises(ValueError, BZ2File, "/dev/null", "rbt")
-        self.assertRaises(ValueError, BZ2File, "/dev/null", compresslevel=0)
-        self.assertRaises(ValueError, BZ2File, "/dev/null", compresslevel=10)
+        self.assertRaises(ValueError, BZ2File, os.devnull, "z")
+        self.assertRaises(ValueError, BZ2File, os.devnull, "rx")
+        self.assertRaises(ValueError, BZ2File, os.devnull, "rbt")
+        self.assertRaises(ValueError, BZ2File, os.devnull, compresslevel=0)
+        self.assertRaises(ValueError, BZ2File, os.devnull, compresslevel=10)
 
     def testRead(self):
         self.createTempFile()

Lib/test/test_cgi.py

@@ -186,9 +186,9 @@ def test_log(self):
         cgi.initlog("%s", "Testing initlog 1")
         cgi.log("%s", "Testing log 2")
         self.assertEqual(cgi.logfp.getvalue(), "Testing initlog 1\nTesting log 2\n")
-        if os.path.exists("/dev/null"):
+        if os.path.exists(os.devnull):
             cgi.logfp = None
-            cgi.logfile = "/dev/null"
+            cgi.logfile = os.devnull
             cgi.initlog("%s", "Testing log 3")
             self.addCleanup(cgi.closelog)
             cgi.log("Testing log 4")

Lib/test/test_subprocess.py

@@ -1922,7 +1922,7 @@ def test_close_fds(self):
         open_fds = set(fds)
         # add a bunch more fds
         for _ in range(9):
-            fd = os.open("/dev/null", os.O_RDONLY)
+            fd = os.open(os.devnull, os.O_RDONLY)
             self.addCleanup(os.close, fd)
             open_fds.add(fd)
 
@@ -1984,7 +1984,7 @@ def test_close_fds_when_max_fd_is_lowered(self):
         open_fds = set()
         # Add a bunch more fds to pass down.
         for _ in range(40):
-            fd = os.open("/dev/null", os.O_RDONLY)
+            fd = os.open(os.devnull, os.O_RDONLY)
             open_fds.add(fd)
 
         # Leave a two pairs of low ones available for use by the