Fix deprecation warnings in test_os.py

Lib/test/test_os.py

@@ -500,14 +500,16 @@ class DevNullTests (unittest.TestCase):
 class URandomTests (unittest.TestCase):
     def test_urandom(self):
         try:
-            self.assertEqual(len(os.urandom(1)), 1)
-            self.assertEqual(len(os.urandom(10)), 10)
-            self.assertEqual(len(os.urandom(100)), 100)
-            self.assertEqual(len(os.urandom(1000)), 1000)
-            # see http://bugs.python.org/issue3708
-            self.assertEqual(len(os.urandom(0.9)), 0)
-            self.assertEqual(len(os.urandom(1.1)), 1)
-            self.assertEqual(len(os.urandom(2.0)), 2)
+            with test_support._check_py3k_warnings(
+                ('integer argument expected, got float', DeprecationWarning)):
+                self.assertEqual(len(os.urandom(1)), 1)
+                self.assertEqual(len(os.urandom(10)), 10)
+                self.assertEqual(len(os.urandom(100)), 100)
+                self.assertEqual(len(os.urandom(1000)), 1000)
+                # see http://bugs.python.org/issue3708
+                self.assertEqual(len(os.urandom(0.9)), 0)
+                self.assertEqual(len(os.urandom(1.1)), 1)
+                self.assertEqual(len(os.urandom(2.0)), 2)
         except NotImplementedError:
             pass