Make RawBatchValuesIteratorAdapter length equal to its internal BatchValuesIter length

scylla-cql/src/types/serialize/raw_batch.rs

@@ -52,11 +52,7 @@ pub trait RawBatchValuesIterator<'a> {
     where
         Self: Sized,
     {
-        let mut count = 0;
-        while self.skip_next().is_some() {
-            count += 1;
-        }
-        count
+        std::iter::from_fn(|| self.skip_next()).count()
     }
 }
 
@@ -145,19 +141,26 @@ where
 {
     #[inline]
     fn serialize_next(&mut self, writer: &mut RowWriter) -> Option<Result<(), SerializationError>> {
-        let ctx = self.contexts.next()?;
+        // We do `unwrap_or` because we want the iterator length to be the same
+        // as the amount of values. Limiting to length of the amount of
+        // statements (contexts) causes the caller to not be able to correctly
+        // detect that amount of statements and values is different.
+        let ctx = self
+            .contexts
+            .next()
+            .unwrap_or(RowSerializationContext::empty());
         self.batch_values_iterator.serialize_next(&ctx, writer)
     }
 
     fn is_empty_next(&mut self) -> Option<bool> {
-        self.contexts.next()?;
+        let _ = self.contexts.next();
         let ret = self.batch_values_iterator.is_empty_next()?;
         Some(ret)
     }
 
     #[inline]
     fn skip_next(&mut self) -> Option<()> {
-        self.contexts.next()?;
+        let _ = self.contexts.next();
         self.batch_values_iterator.skip_next()?;
         Some(())
     }

scylla/tests/integration/batch.rs

@@ -0,0 +1,74 @@
+use scylla::batch::Batch;
+use scylla::batch::BatchType;
+use scylla::frame::frame_errors::BatchSerializationError;
+use scylla::frame::frame_errors::CqlRequestSerializationError;
+use scylla::query::Query;
+use scylla::transport::errors::QueryError;
+
+use crate::utils::create_new_session_builder;
+use crate::utils::setup_tracing;
+use crate::utils::unique_keyspace_name;
+use crate::utils::PerformDDL;
+
+use assert_matches::assert_matches;
+
+#[tokio::test]
+#[ntest::timeout(60000)]
+async fn batch_statements_and_values_mismatch_detected() {
+    setup_tracing();
+    let session = create_new_session_builder().build().await.unwrap();
+    let ks = unique_keyspace_name();
+    session.ddl(format!("CREATE KEYSPACE IF NOT EXISTS {} WITH REPLICATION = {{'class' : 'NetworkTopologyStrategy', 'replication_factor' : 1}}", ks)).await.unwrap();
+    session.use_keyspace(ks, false).await.unwrap();
+    session
+        .ddl("CREATE TABLE IF NOT EXISTS batch_serialization_test (p int PRIMARY KEY, val int)")
+        .await
+        .unwrap();
+
+    let mut batch = Batch::new(BatchType::Logged);
+    let stmt = session
+        .prepare("INSERT INTO batch_serialization_test (p, val) VALUES (?, ?)")
+        .await
+        .unwrap();
+    batch.append_statement(stmt.clone());
+    batch.append_statement(Query::new(
+        "INSERT INTO batch_serialization_test (p, val) VALUES (3, 4)",
+    ));
+    batch.append_statement(stmt);
+
+    // Subtest 1: counts are correct
+    {
+        session.batch(&batch, &((1, 2), (), (5, 6))).await.unwrap();
+    }
+
+    // Subtest 2: not enough values
+    {
+        let err = session.batch(&batch, &((1, 2), ())).await.unwrap_err();
+        assert_matches!(
+            err,
+            QueryError::CqlRequestSerialization(CqlRequestSerializationError::BatchSerialization(
+                BatchSerializationError::ValuesAndStatementsLengthMismatch {
+                    n_value_lists: 2,
+                    n_statements: 3
+                }
+            ))
+        )
+    }
+
+    // Subtest 3: too many values
+    {
+        let err = session
+            .batch(&batch, &((1, 2), (), (5, 6), (7, 8)))
+            .await
+            .unwrap_err();
+        assert_matches!(
+            err,
+            QueryError::CqlRequestSerialization(CqlRequestSerializationError::BatchSerialization(
+                BatchSerializationError::ValuesAndStatementsLengthMismatch {
+                    n_value_lists: 4,
+                    n_statements: 3
+                }
+            ))
+        )
+    }
+}

scylla/tests/integration/main.rs

@@ -1,4 +1,5 @@
 mod authenticate;
+mod batch;
 mod consistency;
 mod cql_collections;
 mod cql_types;