diff --git a/zerver/tests/test_migrations_0145.py b/zerver/tests/test_migrations_0145.py
new file mode 100644
index 0000000000..f018f978b3
--- /dev/null
+++ b/zerver/tests/test_migrations_0145.py
@@ -0,0 +1,58 @@
+from zerver.lib.test_classes import MigrationsTestCase
+from zerver.lib.test_helpers import use_db_models, make_client
+from django.utils.timezone import now as timezone_now
+from django.db.migrations.state import StateApps
+from django.db.models.base import ModelBase
+
+from zerver.models import get_stream
+
+class EmojiName2IdTestCase(MigrationsTestCase):
+
+    migrate_from = '0144_remove_realm_create_generic_bot_by_admins_only'
+    migrate_to = '0145_reactions_realm_emoji_name_to_id'
+
+    @use_db_models
+    def setUpBeforeMigration(self, apps: StateApps) -> None:
+        Reaction = apps.get_model('zerver', 'Reaction')
+        RealmEmoji = apps.get_model('zerver', 'RealmEmoji')
+        Message = apps.get_model('zerver', 'Message')
+        Recipient = apps.get_model('zerver', 'Recipient')
+
+        sender = self.example_user('iago')
+        realm = sender.realm
+        sending_client = make_client(name="test suite")
+        stream_name = 'Denmark'
+        stream = get_stream(stream_name, realm)
+        subject = 'foo'
+
+        def send_fake_message(message_content: str, stream: ModelBase) -> ModelBase:
+            recipient = Recipient.objects.get(type_id=stream.id, type=2)
+            return Message.objects.create(sender = sender,
+                                          recipient = recipient,
+                                          subject = subject,
+                                          content = message_content,
+                                          pub_date = timezone_now(),
+                                          sending_client = sending_client)
+        message = send_fake_message('Test 1', stream)
+
+        # Create reactions for all the realm emoji's on the message we faked.
+        for realm_emoji in RealmEmoji.objects.all():
+            reaction = Reaction(user_profile=sender, message=message,
+                                emoji_name=realm_emoji.name, emoji_code=realm_emoji.name,
+                                reaction_type='realm_emoji')
+            reaction.save()
+        realm_emoji_reactions_count = Reaction.objects.filter(reaction_type='realm_emoji').count()
+        self.assertEqual(realm_emoji_reactions_count, 1)
+
+    def test_tags_migrated(self) -> None:
+        Reaction = self.apps.get_model('zerver', 'Reaction')
+        RealmEmoji = self.apps.get_model('zerver', 'RealmEmoji')
+
+        realm_emoji_reactions = Reaction.objects.filter(reaction_type='realm_emoji')
+        realm_emoji_reactions_count = realm_emoji_reactions.count()
+        self.assertEqual(realm_emoji_reactions_count, 1)
+        for reaction in realm_emoji_reactions:
+            realm_emoji = RealmEmoji.objects.get(
+                realm_id=reaction.user_profile.realm_id,
+                name=reaction.emoji_name)
+            self.assertEqual(reaction.emoji_code, str(realm_emoji.id))