should be it

external/duckdb/test/sql/copy/parquet/attach_parquet.test

@@ -0,0 +1,31 @@
+# name: test/sql/copy/parquet/attach_parquet.test
+# description: Attach a Parquet file
+# group: [parquet]
+
+require parquet
+
+require skip_reload
+
+statement ok
+COPY (SELECT 42 val) TO '__TEST_DIR__/file.parquet';
+
+statement ok
+ATTACH '__TEST_DIR__/file.parquet' AS attached_parquet
+
+statement ok
+USE attached_parquet
+
+query I
+SELECT * FROM file
+----
+42
+
+query I
+SELECT * FROM attached_parquet
+----
+42
+
+statement error
+ATTACH 'duckdb:__TEST_DIR__/file.parquet' AS duck_attach
+----
+not a valid DuckDB database file