1 files changed, 68 insertions, 0 deletions
diff --git a/tests/bot/rules/test_discord_emojis.py b/tests/bot/rules/test_discord_emojis.py
new file mode 100644
index 000000000..1c56c9563
--- /dev/null
+++ b/tests/bot/rules/test_discord_emojis.py
@@ -0,0 +1,68 @@
+import unittest
+
+from bot.rules import discord_emojis
+from tests.helpers import MockMessage, async_test
+
+discord_emoji = "<:abcd:1234>"  # Discord emojis follow the format <:name:id>
+
+
+def make_msg(author: str, n_emojis: int) -> MockMessage:
+    """Build a MockMessage instance with content containing `n_emojis` arbitrary emojis."""
+    return MockMessage(author=author, content=discord_emoji * n_emojis)
+
+
+class DiscordEmojisRuleTests(unittest.TestCase):
+    """Tests for the `discord_emojis` antispam rule."""
+
+    def setUp(self):
+        self.config = {"max": 2, "interval": 10}
+
+    @async_test
+    async def test_allows_messages_within_limit(self):
+        """Cases with a total amount of discord emojis within limit."""
+        cases = (
+            [make_msg("bob", 2)],
+            [make_msg("alice", 1), make_msg("bob", 2), make_msg("alice", 1)],
+        )
+
+        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 discord_emojis.apply(last_message, recent_messages, self.config))
+
+    @async_test
+    async def test_disallows_messages_beyond_limit(self):
+        """Cases with more than the allowed amount of discord emojis."""
+        cases = (
+            (
+                [make_msg("bob", 3)],
+                "bob",
+                3,
+            ),
+            (
+                [make_msg("alice", 2), make_msg("bob", 2), make_msg("alice", 2)],
+                "alice",
+                4,
+            ),
+        )
+
+        for recent_messages, culprit, total_emojis in cases:
+            last_message = recent_messages[0]
+            relevant_messages = tuple(msg for msg in recent_messages if msg.author == culprit)
+            expected_output = (
+                f"sent {total_emojis} emojis in {self.config['interval']}s",
+                (culprit,),
+                relevant_messages,
+            )
+
+            with self.subTest(
+                last_message=last_message,
+                recent_messages=recent_messages,
+                config=self.config,
+                expected_output=expected_output,
+            ):
+                self.assertTupleEqual(
+                    await discord_emojis.apply(last_message, recent_messages, self.config),
+                    expected_output,
+                )