Add SQL analyser logic for adding unique constraint

django_migration_linter/sql_analyser/base.py

@@ -73,6 +73,14 @@ class BaseAnalyser(object):
             ),
             "mode": "one_liner",
         },
+        {
+            "code": "ADD_UNIQUE",
+            "fn": lambda sql, **kw: re.search(
+                "ALTER TABLE .* ADD CONSTRAINT .* UNIQUE", sql
+            ),
+            "err_msg": "ADDING unique constraint",
+            "mode": "one_liner",
+        },
     ]
 
     migration_tests = []

django_migration_linter/sql_analyser/sqlite.py

@@ -48,4 +48,8 @@ class SqliteAnalyser(BaseAnalyser):
             ),
             "mode": "transaction",
         },
+        {
+            "code": "ADD_UNIQUE",
+            "fn": lambda sql, **kw: sql.startswith("CREATE UNIQUE INDEX"),
+        },
     ]