From 8c43b54308fa8cf457c86da7cc2e2a72b33fa1f6 Mon Sep 17 00:00:00 2001
From: Sebastian T F <sebastian.tharakan97@gmail.com>
Date: Tue, 20 Feb 2024 10:49:31 +0530
Subject: [PATCH 1/2] test: negative values in csv_parser, mst, range_check

---
 csv/entry_16_negative.csv                     | 17 +++++++++++++++++
 zk_prover/src/merkle_sum_tree/tests.rs        | 19 +++++++++++++++++++
 .../src/merkle_sum_tree/utils/csv_parser.rs   | 12 ++++++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 csv/entry_16_negative.csv

diff --git a/csv/entry_16_negative.csv b/csv/entry_16_negative.csv
new file mode 100644
index 0000000..bd6f16b
--- /dev/null
+++ b/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
diff --git a/zk_prover/src/merkle_sum_tree/tests.rs b/zk_prover/src/merkle_sum_tree/tests.rs
index b79fb22..087415d 100644
--- a/zk_prover/src/merkle_sum_tree/tests.rs
+++ b/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 =
diff --git a/zk_prover/src/merkle_sum_tree/utils/csv_parser.rs b/zk_prover/src/merkle_sum_tree/utils/csv_parser.rs
index 5df9c44..c5bd8ea 100644
--- a/zk_prover/src/merkle_sum_tree/utils/csv_parser.rs
+++ b/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());
+    }
+}

From 6be12777a41f31f6bab1bdcf56119a05b540912a Mon Sep 17 00:00:00 2001
From: Sebastian T F <sebastian.tharakan97@gmail.com>
Date: Tue, 20 Feb 2024 11:02:34 +0530
Subject: [PATCH 2/2] test: try Fp::from negative values

---
 zk_prover/src/chips/range/tests.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/zk_prover/src/chips/range/tests.rs b/zk_prover/src/chips/range/tests.rs
index 07cc576..95da899 100644
--- a/zk_prover/src/chips/range/tests.rs
+++ b/zk_prover/src/chips/range/tests.rs
@@ -272,6 +272,18 @@ mod testing {
         );
     }
 
+    /* #[test]
+    // test converting negative value to Fp for use in range_check chip
+    fn test_negative_value() {
+        let a = Fp::from(-1i8);
+        /* 
+          the trait bound `halo2_proofs::halo2curves::bn256::Fr: From<i8>` is not satisfied
+          the following other types implement trait `From<T>`:
+            <halo2_proofs::halo2curves::bn256::Fr as From<bool>>
+            <halo2_proofs::halo2curves::bn256::Fr as From<u64>>
+        */
+    } */
+
     #[cfg(feature = "dev-graph")]
     #[test]
     fn print_range_check_test() {