Fix invalid escape sequence: use raw string. (GH-6225)

ericvsmith · web-flow · commit c42e7aa67ce7 · 2018-03-24T23:02:21.000-04:00
diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
@@ -2667,7 +2667,7 @@ class C:
         # There was a bug where a variable in a slot was assumed
         #  to also have a default value (of type types.MemberDescriptorType).
         with self.assertRaisesRegex(TypeError,
-                                    "__init__\(\) missing 1 required positional argument: 'x'"):
+                                    r"__init__\(\) missing 1 required positional argument: 'x'"):
             C()
 
         # We can create an instance, and assign to x.
