tests: add test case for result_metadata update

scylla/src/transport/session_test.rs

@@ -1968,6 +1968,87 @@ async fn test_unprepared_reprepare_in_execute() {
     assert_eq!(all_rows, vec![(1, 2, 3), (1, 3, 2)]);
 }
 
+#[tokio::test]
+async fn test_use_prepared_result_metadata() {
+    let _ = tracing_subscriber::fmt::try_init();
+
+    let session = create_new_session_builder()
+        .skip_prepared_statement_result_metadata(true)
+        .build()
+        .await
+        .unwrap();
+    let ks = unique_keyspace_name();
+
+    session.query(format!("CREATE KEYSPACE IF NOT EXISTS {} WITH REPLICATION = {{'class' : 'NetworkTopologyStrategy', 'replication_factor' : 1}}", ks), &[]).await.unwrap();
+    session.use_keyspace(ks, false).await.unwrap();
+
+    session
+        .query(
+            "CREATE TABLE IF NOT EXISTS tab (a int PRIMARY KEY, b int, c int)",
+            &[],
+        )
+        .await
+        .unwrap();
+
+    let insert_a_b_c = session
+        .prepare("INSERT INTO tab (a, b, c) VALUES (?, ?, ?)")
+        .await
+        .unwrap();
+    let select_star = session.prepare("SELECT * FROM tab").await.unwrap();
+
+    let select_col_types = select_star
+        .get_result_metadata()
+        .col_specs
+        .iter()
+        .map(|c| c.typ.clone())
+        .collect::<Vec<_>>();
+
+    assert_eq!(
+        vec![ColumnType::Int, ColumnType::Int, ColumnType::Int],
+        select_col_types
+    );
+
+    session.execute(&insert_a_b_c, (1, 2, 3)).await.unwrap();
+    session.execute(&insert_a_b_c, (3, 4, -1)).await.unwrap();
+
+    session
+        .query("ALTER TABLE tab ALTER c TYPE blob", &[])
+        .await
+        .unwrap();
+
+    // The type of `c` should change to blob after reprepare.
+    let all_rows: Vec<(i32, i32, Vec<u8>)> = session
+        .execute(&select_star, &[])
+        .await
+        .unwrap()
+        .rows_typed::<(i32, i32, Vec<u8>)>()
+        .unwrap()
+        .map(|r| r.unwrap())
+        .collect();
+
+    // Third column deserialized as raw bytes.
+    assert_eq!(
+        vec![
+            (1, 2, vec![0x00, 0x00, 0x00, 0x03]),
+            (3, 4, vec![0xff, 0xff, 0xff, 0xff])
+        ],
+        all_rows
+    );
+
+    // Verify that result_metadata of the SELECT query got updated.
+    let select_col_types = select_star
+        .get_result_metadata()
+        .col_specs
+        .iter()
+        .map(|c| c.typ.clone())
+        .collect::<Vec<_>>();
+
+    assert_eq!(
+        vec![ColumnType::Int, ColumnType::Int, ColumnType::Blob],
+        select_col_types
+    );
+}
+
 #[tokio::test]
 async fn test_unusual_valuelists() {
     let _ = tracing_subscriber::fmt::try_init();