A test for public statements

A public statement is one with either no private Scalars, or for which
the coefficient on all private Scalars is 0.

tests/pubstatements.rs

@@ -0,0 +1,29 @@
+#![allow(non_snake_case)]
+use curve25519_dalek::ristretto::RistrettoPoint as G;
+use group::ff::PrimeField;
+use group::Group;
+use sigma_compiler::*;
+
+#[test]
+fn pubstatements_test() -> Result<(), sigma_rs::errors::Error> {
+    sigma_compiler! { proof,
+        (x, pub a),
+        (C, D, const cind B),
+        C = a*x*B,
+        D = a*B,
+    }
+
+    type Scalar = <G as Group>::Scalar;
+    let mut rng = rand::thread_rng();
+    let B = G::generator();
+    let x = Scalar::from_u128(5);
+    let a = Scalar::from_u128(0);
+    let C = a * x * B;
+    let D = a * B;
+
+    let instance = proof::Instance { C, D, B, a };
+    let witness = proof::Witness { x };
+
+    let proof = proof::prove(&instance, &witness, b"pubstatements_test", &mut rng)?;
+    proof::verify(&instance, &proof, b"pubstatements_test")
+}