Make RuleTest use ABCMeta

This will prevent child classes to be instantiated unless they implement
all abstract methods, leading to a more descriptive error message.

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/bot/rules/__init__.py b/tests/bot/rules/__init__.py
index d7cd7b66b..36c986fe1 100644
--- a/tests/bot/rules/__init__.py
+++ b/tests/bot/rules/__init__.py
@@ -1,5 +1,5 @@
 import unittest
-from abc import abstractmethod
+from abc import ABCMeta, abstractmethod
 from typing import Callable, Dict, Iterable, List, NamedTuple, Tuple
 
 from tests.helpers import MockMessage
@@ -12,7 +12,7 @@ class DisallowedCase(NamedTuple):
     n_violations: int
 
 
-class RuleTest(unittest.TestCase):
+class RuleTest(unittest.TestCase, metaclass=ABCMeta):
     """
     Abstract class for antispam rule test cases.