add test enforce_max_block_size

This hasn't really be tested yet, but it is how I plan on testing this.

sequencer/src/block/payload.rs

@@ -351,6 +351,31 @@ mod test {
 
     const NUM_STORAGE_NODES: usize = 10;
 
+    #[test]
+    fn enforce_max_block_size() {
+        let mut rng = jf_utils::test_rng();
+        let max_block_size = 1000u64;
+        let payload_size = 10;
+
+        let len = max_block_size;
+        // let mut txs: Vec<Transaction> = vec![];
+        let mut txs = (0..max_block_size / payload_size)
+            .map(|_| Transaction::of_size(&mut rng, payload_size))
+            .collect::<Vec<Transaction>>();
+
+        // should panic b/c txs size > max_block_size
+        txns.push(Transaction::of_size(&mut rng, payload_size));
+        Payload::<TxTableEntryWord>::from_txs(txs, max_block_size).unwrap();
+
+        // should panic b/c txs size = max_block_size
+        txns.pop(Transaction::of_size(&mut rng, payload_size));
+        Payload::<TxTableEntryWord>::from_txs(txs, max_block_size).unwrap();
+
+        // should succeed b/c txs size < max_block_size
+        txns.pop(Transaction::of_size(&mut rng, payload_size));
+        Payload::<TxTableEntryWord>::from_txs(txs, max_block_size).unwrap();
+    }
+
     #[test]
     fn basic_correctness() {
         check_basic_correctness::<TxTableEntryWord>()

sequencer/src/transaction.rs

@@ -75,6 +75,15 @@ impl Transaction {
             (0..len).map(|_| rand::random::<u8>()).collect::<Vec<_>>(),
         )
     }
+    #[cfg(any(test, feature = "testing"))]
+    /// Useful for when we want to test size of transaction(s)
+    pub fn of_size(rng: &mut dyn rand::RngCore, len: usize) -> Self {
+        use rand::Rng;
+        Self::new(
+            NamespaceId(rng.gen_range(0..10)),
+            (0..len).map(|_| rand::random::<u8>()).collect::<Vec<_>>(),
+        )
+    }
 }
 
 impl HotShotTransaction for Transaction {}