test(evm): cover ForkDbStateSnapshot::storage_ref snapshot lookup

Author: gutonosa

crates/evm/core/src/fork/database.rs

@@ -301,4 +301,28 @@ mod tests {
         assert!(loaded.is_some());
         assert_eq!(loaded.unwrap(), info);
     }
+
+    /// Verifies that `ForkDbStateSnapshot::storage_ref` reads from `state_snapshot.storage`
+    /// when the slot is missing from `local.cache.accounts`. Without this lookup the call
+    /// would fall through to the backend and return the unrelated remote value.
+    #[tokio::test(flavor = "multi_thread")]
+    async fn fork_db_state_snapshot_reads_storage_from_snapshot() {
+        let rpc = foundry_test_utils::rpc::next_http_rpc_endpoint();
+        let provider = get_http_provider(rpc.clone());
+        let meta = BlockchainDbMeta::new(Default::default(), rpc);
+        let db = BlockchainDb::new(meta, None);
+        let backend = SharedBackend::spawn_backend(Arc::new(provider), db, None).await;
+
+        let address = Address::random();
+        let slot = U256::from(42u64);
+        let expected = U256::from(0xdeadbeefu64);
+
+        let mut state_snapshot = StateSnapshot::default();
+        state_snapshot.storage.entry(address).or_default().insert(slot, expected);
+
+        let snapshot = ForkDbStateSnapshot { local: CacheDB::new(backend), state_snapshot };
+
+        let got = DatabaseRef::storage_ref(&snapshot, address, slot).unwrap();
+        assert_eq!(got, expected);
+    }
 }