helper function: Circuit::test_proof_and_verify()

halo2_proofs/examples/simple-example.rs

@@ -6,6 +6,7 @@ use halo2_proofs::{
     plonk::{Advice, Circuit, Column, ConstraintSystem, Error, Fixed, Instance, Selector},
     poly::Rotation,
 };
+use pasta_curves::EqAffine;
 
 // ANCHOR: instructions
 trait NumericInstructions<F: Field>: Chip<F> {
@@ -237,7 +238,7 @@ impl<F: Field> NumericInstructions<F> for FieldChip<F> {
 /// In this struct we store the private input variables. We use `Option<F>` because
 /// they won't have any value during key generation. During proving, if any of these
 /// were `None` we would get an error.
-#[derive(Default)]
+#[derive(Copy, Clone)]
 struct MyCircuit<F: Field> {
     constant: F,
     a: Value<F>,
@@ -250,7 +251,11 @@ impl<F: Field> Circuit<F> for MyCircuit<F> {
     type FloorPlanner = SimpleFloorPlanner;
 
     fn without_witnesses(&self) -> Self {
-        Self::default()
+        Self {
+            constant: self.constant,
+            a: Value::default(),
+            b: Value::default(),
+        }
     }
 
     fn configure(meta: &mut ConstraintSystem<F>) -> Self::Config {
@@ -308,7 +313,7 @@ fn main() {
     // ANCHOR: test-circuit
     // The number of rows in our circuit cannot exceed 2^k. Since our example
     // circuit is very small, we can pick a very small value here.
-    let k = 4;
+    const K: u32 = 4;
 
     // Prepare the private and public inputs to the circuit!
     let constant = Fp::from(7);
@@ -328,12 +333,14 @@ fn main() {
     let mut public_inputs = vec![c];
 
     // Given the correct public input, our circuit will verify.
-    let prover = MockProver::run(k, &circuit, vec![public_inputs.clone()]).unwrap();
+    let prover = MockProver::run(K, &circuit, vec![public_inputs.clone()]).unwrap();
     assert_eq!(prover.verify(), Ok(()));
 
+    assert!(circuit.test_prove_and_verify::<K, EqAffine>(&[&public_inputs]));
+
     // If we try some other public input, the proof will fail!
     public_inputs[0] += Fp::one();
-    let prover = MockProver::run(k, &circuit, vec![public_inputs]).unwrap();
+    let prover = MockProver::run(K, &circuit, vec![public_inputs]).unwrap();
     assert!(prover.verify().is_err());
     // ANCHOR_END: test-circuit
 }

halo2_proofs/src/plonk/circuit.rs

@@ -11,6 +11,7 @@ use crate::{
     circuit::{Layouter, Region, Value},
     poly::Rotation,
 };
+use pasta_curves::arithmetic::CurveAffine;
 
 mod compress_selectors;
 
@@ -482,6 +483,42 @@ pub trait Circuit<F: Field> {
     /// the caller will be different depending on the context, and they may or
     /// may not expect to have a witness present.
     fn synthesize(&self, config: Self::Config, layouter: impl Layouter<F>) -> Result<(), Error>;
+
+    /// Test proof creation and verification for this circuit.
+    fn test_prove_and_verify<const K: u32, C>(self, instance: &[&[C::Scalar]]) -> bool
+    where
+        C: CurveAffine<ScalarExt = F>,
+        C::Scalar: ff::FromUniformBytes<64>,
+        Self: Sized,
+    {
+        use crate::{
+            plonk::{create_proof, keygen_pk, keygen_vk, verify_proof, SingleVerifier},
+            poly::commitment::Params,
+            transcript::{Blake2bRead, Blake2bWrite, Challenge255},
+        };
+
+        let params = Params::<C>::new(K);
+
+        let vk = keygen_vk(&params, &self.without_witnesses()).expect("keygen_vk should not fail");
+        let pk =
+            keygen_pk(&params, vk, &self.without_witnesses()).expect("keygen_pk should not fail");
+
+        let mut transcript = Blake2bWrite::<_, _, Challenge255<C>>::init(vec![]);
+        create_proof(
+            &params,
+            &pk,
+            &[self],
+            &[instance],
+            rand_core::OsRng,
+            &mut transcript,
+        )
+        .expect("proof generation should not fail");
+        let proof: Vec<u8> = transcript.finalize();
+
+        let strategy = SingleVerifier::new(&params);
+        let mut transcript = Blake2bRead::<_, _, Challenge255<_>>::init(&proof[..]);
+        verify_proof(&params, pk.get_vk(), strategy, &[instance], &mut transcript).is_ok()
+    }
 }
 
 /// Low-degree expression representing an identity that must hold over the committed columns.