Fix syntax warnings in tests introduced in bpo-15248. (GH-11932)

Lib/test/test_bytes.py

@@ -852,9 +852,10 @@ class BytesTest(BaseBytesTest, unittest.TestCase):
     type2test = bytes
 
     def test_getitem_error(self):
+        b = b'python'
         msg = "byte indices must be integers or slices"
         with self.assertRaisesRegex(TypeError, msg):
-            b'python'['a']
+            b['a']
 
     def test_buffer_is_readonly(self):
         fd = os.open(__file__, os.O_RDONLY)
@@ -1042,14 +1043,15 @@ class ByteArrayTest(BaseBytesTest, unittest.TestCase):
     type2test = bytearray
 
     def test_getitem_error(self):
+        b = bytearray(b'python')
         msg = "bytearray indices must be integers or slices"
         with self.assertRaisesRegex(TypeError, msg):
-            bytearray(b'python')['a']
+            b['a']
 
     def test_setitem_error(self):
+        b = bytearray(b'python')
         msg = "bytearray indices must be integers or slices"
         with self.assertRaisesRegex(TypeError, msg):
-            b = bytearray(b'python')
             b['a'] = "python"
 
     def test_nohash(self):