Add internal classes and add type hints + mypy.

django_migration_linter/sql_analyser/mysql.py

@@ -1,22 +1,26 @@
+from __future__ import annotations
+
 import re
 
-from .base import BaseAnalyser
+from .base import BaseAnalyser, Check, CheckMode, CheckType
 
 
 class MySqlAnalyser(BaseAnalyser):
-    migration_tests = [
-        {
-            "code": "ALTER_COLUMN",
-            "fn": lambda sql, **kw: re.search(
-                "ALTER TABLE .* MODIFY .* (?!NULL);?$", sql
+    migration_checks: list[Check] = [
+        Check(
+            code="ALTER_COLUMN",
+            fn=lambda sql, **kw: re.search("ALTER TABLE .* MODIFY .* (?!NULL);?$", sql),
+            message=(
+                "ALTERING columns (Could be backward compatible. "
+                "You may ignore this migration.)"
             ),
-            "mode": "one_liner",
-            "type": "error",
-        }
+            mode=CheckMode.ONE_LINER,
+            type=CheckType.ERROR,
+        ),
     ]
 
     @staticmethod
-    def detect_column(sql):
+    def detect_column(sql: list[str] | str) -> str | None:
         if isinstance(sql, str):
             regex_result = re.search("COLUMN [`\"'](.*?)[`\"']", sql, re.IGNORECASE)
             if regex_result:
@@ -24,3 +28,4 @@ class MySqlAnalyser(BaseAnalyser):
             regex_result = re.search("MODIFY [`\"'](.*?)[`\"']", sql, re.IGNORECASE)
             if regex_result:
                 return regex_result.group(1)
+        return None