From d727f84a56f373fdb09b5ab07b1c1378da1efb78 Mon Sep 17 00:00:00 2001
From: wborgeaud <williamborgeaud@gmail.com>
Date: Tue, 8 Jun 2021 11:18:21 +0200
Subject: [PATCH] Working test

---
 src/field/extension_field/algebra.rs |  4 +-
 src/gates/interpolation.rs           | 68 ++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/src/field/extension_field/algebra.rs b/src/field/extension_field/algebra.rs
index db80ce75..7a4f43a3 100644
--- a/src/field/extension_field/algebra.rs
+++ b/src/field/extension_field/algebra.rs
@@ -38,7 +38,7 @@ impl<F: OEF<D>, const D: usize> Display for ExtensionAlgebra<F, D> {
         for i in 1..D - 1 {
             write!(f, "({})*b^{} + ", self.0[i], i)?;
         }
-        write!(f, "{}*b^{}", self.0[D - 1], D - 1)
+        write!(f, "({})*b^{}", self.0[D - 1], D - 1)
     }
 }
 
@@ -112,7 +112,7 @@ impl<F: OEF<D>, const D: usize> Mul for ExtensionAlgebra<F, D> {
                 res[(i + j) % D] += if i + j < D {
                     self.0[i] * rhs.0[j]
                 } else {
-                    w * self.0[i] * rhs.0[i]
+                    w * self.0[i] * rhs.0[j]
                 }
             }
         }
diff --git a/src/gates/interpolation.rs b/src/gates/interpolation.rs
index 3872b9ee..804b9310 100644
--- a/src/gates/interpolation.rs
+++ b/src/gates/interpolation.rs
@@ -282,9 +282,14 @@ mod tests {
     use std::marker::PhantomData;
 
     use crate::field::crandall_field::CrandallField;
+    use crate::field::extension_field::quartic::QuarticCrandallField;
+    use crate::field::extension_field::FieldExtension;
+    use crate::field::field::Field;
     use crate::gates::gate::Gate;
     use crate::gates::gate_testing::test_low_degree;
     use crate::gates::interpolation::InterpolationGate;
+    use crate::polynomial::polynomial::PolynomialCoeffs;
+    use crate::vars::EvaluationVars;
 
     #[test]
     fn wire_indices() {
@@ -311,4 +316,67 @@ mod tests {
         type F = CrandallField;
         test_low_degree(InterpolationGate::<F, 4>::new(4));
     }
+
+    #[test]
+    fn test_gate_constraint() {
+        type F = CrandallField;
+        type FF = QuarticCrandallField;
+        const D: usize = 4;
+
+        /// Returns the local wires for an interpolation gate for given coeffs, points and eval point.
+        fn get_wires(
+            num_points: usize,
+            coeffs: PolynomialCoeffs<FF>,
+            points: Vec<F>,
+            eval_point: FF,
+        ) -> Vec<FF> {
+            let mut v = vec![F::ZERO; num_points * 5 + (coeffs.len() + 3) * D];
+            for j in 0..num_points {
+                v[j] = points[j];
+            }
+            for j in 0..num_points {
+                for i in 0..D {
+                    v[num_points + D * j + i] = <FF as FieldExtension<D>>::to_basefield_array(
+                        &coeffs.eval(points[j].into()),
+                    )[i];
+                }
+            }
+            for i in 0..D {
+                v[num_points * 5 + i] =
+                    <FF as FieldExtension<D>>::to_basefield_array(&eval_point)[i];
+            }
+            for i in 0..D {
+                v[num_points * 5 + D + i] =
+                    <FF as FieldExtension<D>>::to_basefield_array(&coeffs.eval(eval_point))[i];
+            }
+            for i in 0..coeffs.len() {
+                for (j, input) in
+                    (0..D).zip(num_points * 5 + (2 + i) * D..num_points * 5 + (3 + i) * D)
+                {
+                    v[input] = <FF as FieldExtension<D>>::to_basefield_array(&coeffs.coeffs[i])[j];
+                }
+            }
+            v.iter().map(|&x| x.into()).collect::<Vec<_>>()
+        }
+
+        /// Get a working row for InterpolationGate.
+        let coeffs = PolynomialCoeffs::new(vec![FF::rand(), FF::rand()]);
+        let points = vec![F::rand(), F::rand()];
+        let eval_point = FF::rand();
+        let gate = InterpolationGate::<F, D> {
+            num_points: 2,
+            _phantom: PhantomData,
+        };
+        let vars = EvaluationVars {
+            local_constants: &[],
+            local_wires: &get_wires(2, coeffs, points, eval_point),
+        };
+
+        assert!(
+            gate.eval_unfiltered(vars.clone())
+                .iter()
+                .all(|x| x.is_zero()),
+            "Gate constraints are not satisfied."
+        );
+    }
 }