Refs #30593 -- Added _parse_constraint_columns() hook to introspection on MariaDB.

tests/backends/mysql/test_introspection.py

@@ -0,0 +1,22 @@
+from unittest import skipUnless
+
+from django.db import connection
+from django.test import TestCase
+
+
+@skipUnless(connection.vendor == 'mysql', 'MySQL tests')
+class ParsingTests(TestCase):
+    def test_parse_constraint_columns(self):
+        tests = (
+            ('`height` >= 0', ['height']),
+            ('`cost` BETWEEN 1 AND 10', ['cost']),
+            ('`ref1` > `ref2`', ['ref1', 'ref2']),
+            (
+                '`start` IS NULL OR `end` IS NULL OR `start` < `end`',
+                ['start', 'end'],
+            ),
+        )
+        for check_clause, expected_columns in tests:
+            with self.subTest(check_clause):
+                check_columns = connection.introspection._parse_constraint_columns(check_clause)
+                self.assertEqual(list(check_columns), expected_columns)