✅ add tests for escaping and quoting of MySQL identifiers in table creation

Author: techouse

tests/unit/test_build_create_table_sql_sqlglot_identifiers.py

@@ -0,0 +1,98 @@
+from unittest.mock import MagicMock, patch
+
+from mysql_to_sqlite3.transporter import MySQLtoSQLite
+
+
+def _make_base_instance():
+    with patch.object(MySQLtoSQLite, "__init__", return_value=None):
+        inst = MySQLtoSQLite()  # type: ignore[call-arg]
+    inst._mysql_cur_dict = MagicMock()
+    inst._mysql_database = "db"
+    inst._sqlite_json1_extension_enabled = False
+    inst._collation = "BINARY"
+    inst._prefix_indices = False
+    inst._without_tables = False
+    inst._without_foreign_keys = True
+    inst._logger = MagicMock()
+    inst._sqlite_strict = False
+    # Track index names for uniqueness
+    inst._seen_sqlite_index_names = set()
+    inst._sqlite_index_name_counters = {}
+    return inst
+
+
+def test_show_columns_backticks_are_escaped_in_mysql_query() -> None:
+    inst = _make_base_instance()
+
+    # Capture executed SQL
+    executed_sql = []
+
+    def capture_execute(sql: str, *args, **kwargs):
+        executed_sql.append(sql)
+
+    inst._mysql_cur_dict.execute.side_effect = capture_execute
+
+    # SHOW COLUMNS -> then STATISTICS query
+    inst._mysql_cur_dict.fetchall.side_effect = [
+        [
+            {
+                "Field": "id",
+                "Type": "INT",
+                "Null": "NO",
+                "Default": None,
+                "Key": "PRI",
+                "Extra": "",
+            }
+        ],
+        [],
+    ]
+    # TABLE collision check -> 0
+    inst._mysql_cur_dict.fetchone.return_value = {"count": 0}
+
+    sql = inst._build_create_table_sql("we`ird")
+    assert sql.startswith('CREATE TABLE IF NOT EXISTS "we`ird" (')
+
+    # First executed SQL should be SHOW COLUMNS with backticks escaped
+    assert executed_sql
+    assert executed_sql[0] == "SHOW COLUMNS FROM `we``ird`"
+
+
+def test_identifiers_with_double_quotes_are_safely_quoted_in_create_and_index() -> None:
+    inst = _make_base_instance()
+    inst._prefix_indices = True  # ensure an index is emitted with a deterministic name prefix
+
+    # SHOW COLUMNS first call, then STATISTICS rows
+    inst._mysql_cur_dict.fetchall.side_effect = [
+        [
+            {
+                "Field": 'na"me',
+                "Type": "VARCHAR(10)",
+                "Null": "YES",
+                "Default": None,
+                "Key": "",
+                "Extra": "",
+            },
+        ],
+        [
+            {
+                "name": "idx",
+                "primary": 0,
+                "unique": 0,
+                "auto_increment": 0,
+                "columns": 'na"me',
+                "types": "VARCHAR(10)",
+            }
+        ],
+    ]
+    inst._mysql_cur_dict.fetchone.return_value = {"count": 0}
+
+    sql = inst._build_create_table_sql('ta"ble')
+
+    # Column should be quoted with doubled quotes inside
+    assert '"na""me" VARCHAR(10)' in sql or '"na""me" TEXT' in sql
+
+    # Index should quote table and column names with doubled quotes
+    assert (
+        'CREATE  INDEX IF NOT EXISTS "ta""ble_idx" ON "ta""ble" ("na""me");' in sql
+        or 'CREATE  INDEX IF NOT EXISTS "ta""ble_idx" ON "ta""ble" ("na""me")' in sql
+    )