test(mempool): test max num inputs on insertion

Author: Sword-Smith

src/models/state/mempool.rs

@@ -1969,4 +1969,54 @@ mod tests {
             ));
         }
     }
+
+    #[cfg(test)]
+    mod restrict_num_inputs {
+        use super::*;
+        use crate::models::blockchain::transaction::transaction_kernel::transaction_kernel_tests::pseudorandom_transaction_kernel;
+
+        /// Return an invalid SingleProof-backed transaction with `n` inputs.
+        fn tx_with_n_inputs(n: usize) -> Transaction {
+            let mut rng = rand::rng();
+            let num_outputs = 10;
+            let num_public_announcements = 10;
+            let kernel = pseudorandom_transaction_kernel(
+                rng.random(),
+                n,
+                num_outputs,
+                num_public_announcements,
+            );
+            Transaction {
+                kernel,
+                proof: TransactionProof::invalid(),
+            }
+        }
+
+        #[test]
+        fn cannot_insert_tx_with_too_many_inputs() {
+            let network = Network::Main;
+            let genesis_block = Block::genesis(network);
+            let max_inputs_per_tx = 5;
+            let mut mempool = Mempool::new(
+                ByteSize::gb(1),
+                None,
+                Some(max_inputs_per_tx),
+                genesis_block.hash(),
+            );
+
+            for i in 0..=max_inputs_per_tx {
+                let tx = tx_with_n_inputs(i);
+                assert!(mempool.insert(tx, TransactionOrigin::Foreign).is_ok());
+            }
+
+            assert_eq!(max_inputs_per_tx + 1, mempool.len());
+            assert!(mempool
+                .insert(
+                    tx_with_n_inputs(max_inputs_per_tx + 1),
+                    TransactionOrigin::Foreign
+                )
+                .is_err());
+            assert_eq!(max_inputs_per_tx + 1, mempool.len());
+        }
+    }
 }