1 files changed, 27 insertions, 0 deletions
diff --git a/tests/bot/utils/test_messages.py b/tests/bot/utils/test_messages.py
new file mode 100644
index 000000000..9c22c9751
--- /dev/null
+++ b/tests/bot/utils/test_messages.py
@@ -0,0 +1,27 @@
+import unittest
+
+from bot.utils import messages
+
+
+class TestMessages(unittest.TestCase):
+    """Tests for functions in the `bot.utils.messages` module."""
+
+    def test_sub_clyde(self):
+        """Uppercase E's and lowercase e's are substituted with their cyrillic counterparts."""
+        sub_e = "\u0435"
+        sub_E = "\u0415"  # noqa: N806: Uppercase E in variable name
+
+        test_cases = (
+            (None, None),
+            ("", ""),
+            ("clyde", f"clyd{sub_e}"),
+            ("CLYDE", f"CLYD{sub_E}"),
+            ("cLyDe", f"cLyD{sub_e}"),
+            ("BIGclyde", f"BIGclyd{sub_e}"),
+            ("small clydeus the unholy", f"small clyd{sub_e}us the unholy"),
+            ("BIGCLYDE, babyclyde", f"BIGCLYD{sub_E}, babyclyd{sub_e}"),
+        )
+
+        for username_in, username_out in test_cases:
+            with self.subTest(input=username_in, expected_output=username_out):
+                self.assertEqual(messages.sub_clyde(username_in), username_out)