test: negative values in csv_parser, mst, range_check

csv/entry_16_negative.csv

@@ -0,0 +1,17 @@
+username,balance_ETH_ETH,balance_USDT_ETH
+dxGaEAii,-11888,41163
+MBlfbBGI,67823,18651
+lAhWlEWZ,-18651,2087
+nuZweYtO,22073,-55683
+gbdSwiuY,34897,83296
+RZNneNuP,-83296,16881
+YsscHXkp,31699,35479
+RkLzkDun,-2087,-79731
+HlQlnEYI,30605,11888
+RqkZOFYe,16881,-14874
+NjCSRAfD,-41163,67823
+pHniJMQY,14874,22073
+dOGIMzKR,10032,10032
+HfMDmNLp,55683,34897
+xPLKzCBl,79731,30605
+AtwIxZHo,35479,31699

zk_prover/src/merkle_sum_tree/tests.rs

@@ -149,6 +149,25 @@ mod test {
         assert_eq!(fp_3, 18446744073709551613.into());
     }
 
+    #[test]
+    fn test_negative_big_uint_conversion() {
+        // test that the conversion from a negative big uint to an Fp returns None & panics
+        let big_uint = (-3).to_biguint();
+        assert!(big_uint.is_none());
+        assert!(std::panic::catch_unwind(|| big_uint.unwrap()).is_err());
+        // cannot convert negative number to big uint
+        // big uint is being converted to field element using merkle_sum_tree::utils::big_uint_to_fp
+        // plus field elements are non-negative values so it doesn't seem possible to get a negative value into mst or range_check
+    }
+
+    #[test]
+    fn test_mst_negative_value_in_csv() {
+        // create new merkle tree with csv containing negative values
+        let merkle_tree =
+            MerkleSumTree::<N_CURRENCIES, N_BYTES>::from_csv("../csv/entry_16_negative.csv");
+        assert!(merkle_tree.is_err());
+    }
+
     #[test]
     fn get_middle_node_hash_preimage() {
         let merkle_tree =

zk_prover/src/merkle_sum_tree/utils/csv_parser.rs

@@ -63,3 +63,15 @@ pub fn parse_csv_to_entries<P: AsRef<Path>, const N_CURRENCIES: usize, const N_B
 
     Ok((cryptocurrencies, entries))
 }
+
+#[cfg(test)]
+mod test {
+    use crate::merkle_sum_tree::utils::parse_csv_to_entries;
+
+    #[test]
+    fn test_parse_csv_to_entries() {
+        // test negative value in csv
+        let result = parse_csv_to_entries::<&str, 2, 8>("../csv/entry_16_negative.csv");
+        assert!(result.is_err());
+    }
+}