Add assertion for now next_entry must be called

src/entry.rs

@@ -109,6 +109,7 @@ fn next_hash(start_hash: &Hash, num_hashes: u64, transactions: &[Transaction]) -
 
 /// Creates the next Tick or Transaction Entry `num_hashes` after `start_hash`.
 pub fn next_entry(start_hash: &Hash, num_hashes: u64, transactions: Vec<Transaction>) -> Entry {
+    assert!(num_hashes > 0 || transactions.len() == 0);
     Entry {
         num_hashes,
         id: next_hash(start_hash, num_hashes, &transactions),
@@ -180,4 +181,13 @@ mod tests {
         assert_eq!(tick.num_hashes, 0);
         assert_eq!(tick.id, zero);
     }
+
+    #[test]
+    #[should_panic]
+    fn test_next_entry_panic() {
+        let zero = Hash::default();
+        let keypair = KeyPair::new();
+        let tx = Transaction::new(&keypair, keypair.pubkey(), 0, zero);
+        next_entry(&zero, 0, vec![tx]);
+    }
 }

src/ledger.rs

@@ -179,13 +179,13 @@ mod tests {
         let tx0 = Transaction::new(&keypair, keypair.pubkey(), 1, next_id);
         let transactions = vec![tx0; 5];
         let transaction_batches = vec![transactions.clone(); 5];
-        let entries0 = next_entries(&id, 0, transaction_batches);
+        let entries0 = next_entries(&id, 1, transaction_batches);
 
         assert_eq!(entries0.len(), 5);
 
         let mut entries1 = vec![];
         for _ in 0..5 {
-            let entry = next_entry(&id, 0, transactions.clone());
+            let entry = next_entry(&id, 1, transactions.clone());
             id = entry.id;
             entries1.push(entry);
         }