Correct two bugs in the BucketQueueView. (linera-io#2541)

* Correct one bug to the BucketQueueView where the `self.stored_position` was not updated.
* Correct one bug for the dropping of entries when flushing.
* Update the CI test to detect the problem.

linera-views/src/views/bucket_queue_view.rs

@@ -55,9 +55,10 @@ enum KeyTag {
 /// The `StoredIndices` contains the description of the stored buckets.
 #[derive(Clone, Debug, Default, Serialize, Deserialize)]
 struct StoredIndices {
-    /// The stored buckets with the first index being the size at most N and the
-    /// second one is the index. If the index is 0 then it correspond to the Front,
-    /// otherwise to the Index.
+    /// The stored buckets with the first index being the size (at most N) and the
+    /// second one is the index in the storage. If the index is 0 then it corresponds
+    /// with the first value (entry `KeyTag::Front`), otherwise to the keys with
+    /// prefix `KeyTag::Index`.
     indices: Vec<(usize, usize)>,
     /// The position of the front in the first index.
     position: usize,
@@ -231,15 +232,16 @@ where
             self.stored_data.clear();
             self.stored_position = 0;
         } else if let Some((i_block, position)) = self.cursor.position {
-            for block in 0..i_block {
-                let index = self.stored_data[block].0;
+            for _ in 0..i_block {
+                let block = self.stored_data.pop_front().unwrap();
+                let index = block.0;
                 let key = self.get_index_key(index)?;
                 batch.delete_key(key);
-                self.stored_data.pop_front();
             }
             self.cursor = Cursor {
                 position: Some((0, position)),
             };
+            self.stored_position = position;
             // We need to ensure that the first index is in the front.
             let first_index = self.stored_data[0].0;
             if first_index != 0 {

linera-views/tests/random_container_tests.rs

@@ -427,7 +427,7 @@ async fn bucket_queue_view_mutability_check() -> Result<()> {
             let count = view.queue.count();
             if choice == 0 {
                 // inserting random stuff
-                let n_ins = rng.gen_range(0..10);
+                let n_ins = rng.gen_range(0..100);
                 for _ in 0..n_ins {
                     let val = rng.gen::<u8>();
                     view.queue.push_back(val);