1 files changed, 76 insertions, 0 deletions
diff --git a/tests/bot/rules/__init__.py b/tests/bot/rules/__init__.py
index e69de29bb..d7cd7b66b 100644
--- a/tests/bot/rules/__init__.py
+++ b/tests/bot/rules/__init__.py
@@ -0,0 +1,76 @@
+import unittest
+from abc import abstractmethod
+from typing import Callable, Dict, Iterable, List, NamedTuple, Tuple
+
+from tests.helpers import MockMessage
+
+
+class DisallowedCase(NamedTuple):
+    """Encapsulation for test cases expected to fail."""
+    recent_messages: List[MockMessage]
+    culprits: Iterable[str]
+    n_violations: int
+
+
+class RuleTest(unittest.TestCase):
+    """
+    Abstract class for antispam rule test cases.
+
+    Tests for specific rules should inherit from `RuleTest` and implement
+    `relevant_messages` and `get_report`. Each instance should also set the
+    `apply` and `config` attributes as necessary.
+
+    The execution of test cases can then be delegated to the `run_allowed`
+    and `run_disallowed` methods.
+    """
+
+    apply: Callable  # The tested rule's apply function
+    config: Dict[str, int]
+
+    async def run_allowed(self, cases: Tuple[List[MockMessage], ...]) -> None:
+        """Run all `cases` against `self.apply` expecting them to pass."""
+        for recent_messages in cases:
+            last_message = recent_messages[0]
+
+            with self.subTest(
+                last_message=last_message,
+                recent_messages=recent_messages,
+                config=self.config,
+            ):
+                self.assertIsNone(
+                    await self.apply(last_message, recent_messages, self.config)
+                )
+
+    async def run_disallowed(self, cases: Tuple[DisallowedCase, ...]) -> None:
+        """Run all `cases` against `self.apply` expecting them to fail."""
+        for case in cases:
+            recent_messages, culprits, n_violations = case
+            last_message = recent_messages[0]
+            relevant_messages = self.relevant_messages(case)
+            desired_output = (
+                self.get_report(case),
+                culprits,
+                relevant_messages,
+            )
+
+            with self.subTest(
+                last_message=last_message,
+                recent_messages=recent_messages,
+                relevant_messages=relevant_messages,
+                n_violations=n_violations,
+                config=self.config,
+            ):
+                self.assertTupleEqual(
+                    await self.apply(last_message, recent_messages, self.config),
+                    desired_output,
+                )
+
+    @abstractmethod
+    def relevant_messages(self, case: DisallowedCase) -> Iterable[MockMessage]:
+        """Give expected relevant messages for `case`."""
+        raise NotImplementedError
+
+    @abstractmethod
+    def get_report(self, case: DisallowedCase) -> str:
+        """Give expected error report for `case`."""
+        raise NotImplementedError