Force collation when comparing Denied Names to avoid unwanted collisions (#22767)

* Force collation when comparing Denied Names to avoid unwanted collisions

src/olympia/users/models.py

@@ -17,6 +17,7 @@ from django.core import validators
 from django.core.files.uploadedfile import SimpleUploadedFile
 from django.db import models
 from django.db.models import F, Value
+from django.db.models.functions import Collate
 from django.template import loader
 from django.templatetags.static import static
 from django.urls import reverse
@@ -739,7 +740,9 @@ class DeniedName(ModelBase):
         """
         return (
             DeniedName.objects.annotate(
-                query_field=Value(value, output_field=models.CharField())
+                query_field=Collate(
+                    Value(value, output_field=models.CharField()), 'utf8mb4_0900_ai_ci'
+                )
             )
             .filter(query_field__icontains=F('name'))
             .exists()

src/olympia/users/tests/test_models.py

@@ -922,6 +922,18 @@ class TestDeniedName(TestCase):
         assert not DeniedName.blocked('IE6')
         assert not DeniedName.blocked('testo')
 
+    def test_blocked_emoji(self):
+        assert not DeniedName.blocked('Test 🎧')
+        assert not DeniedName.blocked('Test 🌠')
+
+        denied = DeniedName.objects.create(name='🌠')
+        assert not DeniedName.blocked('Test 🎧')
+        assert DeniedName.blocked('Test 🌠')
+
+        denied.update(name='🎧')
+        assert DeniedName.blocked('Test 🎧')
+        assert not DeniedName.blocked('Test 🌠')
+
 
 class TestIPNetworkUserRestriction(TestCase):
     def test_str(self):