Test CREATE INDEX ON ONLY formatter errors

Author: LucaCappelletti94

tests/sqlparser_postgres.rs

@@ -13054,3 +13054,26 @@ fn parse_create_index_on_only() {
         "sql parser error: Expected: a list of columns in parentheses, found: orders"
     );
 }
+
+#[test]
+fn display_create_index_on_only_propagates_formatter_errors() {
+    use core::fmt::{self, Write};
+
+    struct RejectingWriter(&'static str);
+
+    impl Write for RejectingWriter {
+        fn write_str(&mut self, value: &str) -> fmt::Result {
+            if value == self.0 {
+                Err(fmt::Error)
+            } else {
+                Ok(())
+            }
+        }
+    }
+
+    let stmt = pg().verified_stmt("CREATE INDEX ON ONLY orders(note)");
+    for rejected in ["ON ", "ONLY ", "orders"] {
+        let mut writer = RejectingWriter(rejected);
+        assert_eq!(write!(writer, "{stmt}"), Err(fmt::Error), "{rejected:?}");
+    }
+}