1 files changed, 95 insertions, 0 deletions
diff --git a/tests/bot/rules/test_mentions.py b/tests/bot/rules/test_mentions.py
new file mode 100644
index 000000000..ad49ead32
--- /dev/null
+++ b/tests/bot/rules/test_mentions.py
@@ -0,0 +1,95 @@
+import unittest
+from typing import List, NamedTuple, Tuple
+
+from bot.rules import mentions
+from tests.helpers import MockMessage, async_test
+
+
+class Case(NamedTuple):
+    recent_messages: List[MockMessage]
+    culprit: Tuple[str]
+    total_mentions: int
+
+
+def msg(author: str, total_mentions: int) -> MockMessage:
+    """Makes a message with `total_mentions` mentions."""
+    return MockMessage(author=author, mentions=list(range(total_mentions)))
+
+
+class TestMentions(unittest.TestCase):
+    """Tests applying the `mentions` antispam rule."""
+
+    def setUp(self):
+        self.config = {
+            "max": 2,
+            "interval": 10
+        }
+
+    @async_test
+    async def test_mentions_within_limit(self):
+        """Messages with an allowed amount of mentions."""
+        cases = (
+            [msg("bob", 0)],
+            [msg("bob", 2)],
+            [msg("bob", 1), msg("bob", 1)],
+            [msg("bob", 1), msg("alice", 2)]
+        )
+
+        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 mentions.apply(last_message, recent_messages, self.config)
+                )
+
+    @async_test
+    async def test_mentions_exceeding_limit(self):
+        """Messages with a higher than allowed amount of mentions."""
+        cases = (
+            Case(
+                [msg("bob", 3)],
+                ("bob",),
+                3
+            ),
+            Case(
+                [msg("alice", 2), msg("alice", 0), msg("alice", 1)],
+                ("alice",),
+                3
+            ),
+            Case(
+                [msg("bob", 2), msg("alice", 3), msg("bob", 2)],
+                ("bob",),
+                4
+            )
+        )
+
+        for recent_messages, culprit, total_mentions in cases:
+            last_message = recent_messages[0]
+            relevant_messages = tuple(
+                msg
+                for msg in recent_messages
+                if msg.author == last_message.author
+            )
+
+            with self.subTest(
+                last_message=last_message,
+                recent_messages=recent_messages,
+                relevant_messages=relevant_messages,
+                culprit=culprit,
+                total_mentions=total_mentions,
+                cofig=self.config
+            ):
+                desired_output = (
+                    f"sent {total_mentions} mentions in {self.config['interval']}s",
+                    culprit,
+                    relevant_messages
+                )
+                self.assertTupleEqual(
+                    await mentions.apply(last_message, recent_messages, self.config),
+                    desired_output
+                )