2 files changed, 52 insertions, 0 deletions
diff --git a/tests/rules/__init__.py b/tests/rules/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/tests/rules/__init__.py
diff --git a/tests/rules/test_attachments.py b/tests/rules/test_attachments.py
new file mode 100644
index 000000000..4bb0acf7c
--- /dev/null
+++ b/tests/rules/test_attachments.py
@@ -0,0 +1,52 @@
+import asyncio
+import unittest
+from dataclasses import dataclass
+from typing import Any, List
+
+from bot.rules import attachments
+
+
+# Using `MagicMock` sadly doesn't work for this usecase
+# since it's __eq__ compares the MagicMock's ID. We just
+# want to compare the actual attributes we set.
+@dataclass
+class FakeMessage:
+    author: str
+    attachments: List[Any]
+
+
+def msg(total_attachments: int) -> FakeMessage:
+    return FakeMessage(author='lemon', attachments=list(range(total_attachments)))
+
+
+class AttachmentRuleTests(unittest.TestCase):
+    """Tests applying the `attachment` antispam rule."""
+
+    def test_allows_messages_without_too_many_attachments(self):
+        """Messages without too many attachments are allowed as-is."""
+        cases = (
+            (msg(0), msg(0), msg(0)),
+            (msg(2), msg(2)),
+            (msg(0),),
+        )
+
+        for last_message, *recent_messages in cases:
+            with self.subTest(last_message=last_message, recent_messages=recent_messages):
+                coro = attachments.apply(last_message, recent_messages, {'max': 5})
+                self.assertIsNone(asyncio.run(coro))
+
+    def test_disallows_messages_with_too_many_attachments(self):
+        """Messages with too many attachments trigger the rule."""
+        cases = (
+            ((msg(4), msg(0), msg(6)), [msg(4), msg(6)], 10),
+            ((msg(6),), [msg(6)], 6),
+            ((msg(1),) * 6, [msg(1)] * 6, 6),
+        )
+        for messages, relevant_messages, total in cases:
+            with self.subTest(messages=messages, relevant_messages=relevant_messages, total=total):
+                last_message, *recent_messages = messages
+                coro = attachments.apply(last_message, recent_messages, {'max': 5})
+                self.assertEqual(
+                    asyncio.run(coro),
+                    (f"sent {total} attachments in 5s", ('lemon',), relevant_messages)
+                )