From 0fc7b7f577197384f7a9964b693ee68acd0e6d8f Mon Sep 17 00:00:00 2001
From: Jan Ferdinand Sauer <ferdinand@neptune.cash>
Date: Tue, 23 Apr 2024 14:25:32 +0200
Subject: [PATCH] test: test failure of incorrect last ronud poly

---
 triton-vm/src/fri.rs | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/triton-vm/src/fri.rs b/triton-vm/src/fri.rs
index b842ad6c..00054a61 100644
--- a/triton-vm/src/fri.rs
+++ b/triton-vm/src/fri.rs
@@ -1085,6 +1085,28 @@ mod tests {
         }
     }
 
+    #[proptest]
+    fn incorrect_last_round_polynomial_results_in_verification_failure(
+        #[strategy(arbitrary_fri())] fri: Fri<Tip5>,
+        #[strategy(arbitrary_polynomial())] polynomial: Polynomial<XFieldElement>,
+        #[strategy(arb())] incorrect_coefficients: Vec<XFieldElement>,
+    ) {
+        let codeword = fri.domain.evaluate(&polynomial);
+        let mut proof_stream = ProofStream::new();
+        fri.prove(&codeword, &mut proof_stream).unwrap();
+
+        let mut proof_stream = prepare_proof_stream_for_verification(proof_stream);
+        proof_stream.items.iter_mut().for_each(|item| {
+            if let ProofItem::FriPolynomial(coefficients) = item {
+                *coefficients = incorrect_coefficients.clone();
+            }
+        });
+
+        let verdict = fri.verify(&mut proof_stream, &mut None);
+        let_assert!(Err(err) = verdict);
+        assert!(let LastRoundPolynomialEvaluationMismatch = err);
+    }
+
     #[proptest]
     fn verifying_arbitrary_proof_does_not_panic(
         #[strategy(arbitrary_fri())] fri: Fri<Tip5>,
@@ -1094,7 +1116,7 @@ mod tests {
     }
 
     #[proptest]
-    fn test_barycentric_evaluation(
+    fn polynomial_evaluation_and_barycentric_evaluation_are_equivalent(
         #[strategy(1usize..13)] _log_num_coefficients: usize,
         #[strategy(1usize..6)] log_expansion_factor: usize,
         #[strategy(vec(arb(), 1 << #_log_num_coefficients))] coefficients: Vec<XFieldElement>,