From 47b6b3500ad83a377ff10a420ac373ec1b5e728b Mon Sep 17 00:00:00 2001
From: Mohammad Nassar <mohammad@starkware.co>
Date: Sun, 7 Jul 2024 14:48:58 +0300
Subject: [PATCH] refactor(mempool): add error message in transaction queue

---
 crates/mempool/src/transaction_queue.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/crates/mempool/src/transaction_queue.rs b/crates/mempool/src/transaction_queue.rs
index 7e480286e..bbe80da78 100644
--- a/crates/mempool/src/transaction_queue.rs
+++ b/crates/mempool/src/transaction_queue.rs
@@ -20,8 +20,15 @@ pub struct TransactionQueue {
 impl TransactionQueue {
     /// Adds a transaction to the mempool, ensuring unique keys.
     /// Panics: if given a duplicate tx.
+    // TODO(Mohammad): Add test for two transactions from the same address, expecting specific
+    // assert.
     pub fn insert(&mut self, tx: TransactionReference) {
-        assert_eq!(self.address_to_nonce.insert(tx.sender_address, tx.nonce), None);
+        assert_eq!(
+            self.address_to_nonce.insert(tx.sender_address, tx.nonce),
+            None,
+            "Only a single transaction from the same contract class can be in the mempool at a \
+             time."
+        );
         assert!(
             self.queue.insert(tx.into()),
             "Keys should be unique; duplicates are checked prior."