fix: sqlparse fallback for formatting queries (#30578)

tests/unit_tests/sql/parse_tests.py

@@ -284,6 +284,40 @@ def test_extract_tables_show_tables_from() -> None:
     )
 
 
+def test_format_show_tables() -> None:
+    """
+    Test format when `ast.sql()` raises an exception.
+
+    In that case sqlparse should be used instead.
+    """
+    assert (
+        SQLScript("SHOW TABLES FROM s1 like '%order%'", "mysql").format()
+        == "SHOW TABLES FROM s1 LIKE '%order%'"
+    )
+
+
+def test_format_no_dialect() -> None:
+    """
+    Test format with an engine that has no corresponding dialect.
+    """
+    assert (
+        SQLScript("SELECT col FROM t WHERE col NOT IN (1, 2)", "firebolt").format()
+        == "SELECT col\nFROM t\nWHERE col NOT IN (1,\n                  2)"
+    )
+
+
+def test_split_no_dialect() -> None:
+    """
+    Test the statement split when the engine has no corresponding dialect.
+    """
+    sql = "SELECT col FROM t WHERE col NOT IN (1, 2); SELECT * FROM t; SELECT foo"
+    statements = SQLScript(sql, "firebolt").statements
+    assert len(statements) == 3
+    assert statements[0]._sql == "SELECT col FROM t WHERE col NOT IN (1, 2)"
+    assert statements[1]._sql == "SELECT * FROM t"
+    assert statements[2]._sql == "SELECT foo"
+
+
 def test_extract_tables_show_columns_from() -> None:
     """
     Test `SHOW COLUMNS FROM`.