add AccountStorage.is_empty_entry for tests (solana-labs#29489)

runtime/src/account_storage.rs

@@ -59,6 +59,14 @@ impl AccountStorage {
             .unwrap_or(true)
     }
 
+    /// returns true if there is an entry in the map for 'slot', but it contains no append vec
+    #[cfg(test)]
+    pub(crate) fn is_empty_entry(&self, slot: Slot) -> bool {
+        self.get_slot_stores(slot)
+            .map(|storages| storages.read().unwrap().is_empty())
+            .unwrap_or(false)
+    }
+
     /// initialize the storage map to 'all_storages'
     pub(crate) fn initialize(&mut self, all_storages: AccountStorageMap) {
         assert!(self.map.is_empty());

runtime/src/accounts_db.rs

@@ -16509,7 +16509,7 @@ pub mod tests {
             } else {
                 assert!(db.dirty_stores.is_empty());
             }
-            assert!(db.get_storages_for_slot(slot).unwrap().is_empty());
+            assert!(db.storage.is_empty_entry(slot));
         }
     }
 
@@ -17538,7 +17538,7 @@ pub mod tests {
             &mut AncientSlotPubkeys::default(),
             &mut dropped_roots,
         );
-        assert!(db.get_storages_for_slot(next_slot).unwrap().is_empty());
+        assert!(db.storage.is_empty_entry(next_slot));
         // this removes the storages entry completely from the hashmap for 'next_slot'.
         // Otherwise, we have a zero length vec in that hashmap
         db.handle_dropped_roots_for_ancient(dropped_roots);