chore: add property tests for ABI encoding (#5216)

# Description

## Problem\*

Resolves #5226

## Summary\*

This PR adds property testing to ABI encoding so that we can show that
any valid `Abi` + `InputMap` combination can be abi encoded and decoded
to return the original inputs.

## Additional Context



## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

Cargo.toml

@@ -141,6 +141,8 @@ jsonrpc = { version = "0.16.0", features = ["minreq_http"] }
 flate2 = "1.0.24"
 rand = "0.8.5"
 proptest = "1.2.0"
+proptest-derive = "0.4.0"
+
 
 im = { version = "15.1", features = ["serde"] }
 tracing = "0.1.40"

cspell.json

@@ -166,6 +166,7 @@
         "rfind",
         "rustc",
         "rustup",
+        "sboxed",
         "schnorr",
         "sdiv",
         "secp256k1",

tooling/noirc_abi/Cargo.toml

@@ -22,7 +22,10 @@ num-traits = "0.2"
 [dev-dependencies]
 strum = "0.24"
 strum_macros = "0.24"
+proptest.workspace = true
+proptest-derive.workspace = true
+
 
 [features]
 bn254 = ["acvm/bn254"]
-bls12_381 = ["acvm/bls12_381"]
+bls12_381 = ["acvm/bls12_381"]

tooling/noirc_abi/src/arbitrary.rs

@@ -0,0 +1,154 @@
+use iter_extended::{btree_map, vecmap};
+use prop::collection::vec;
+use proptest::prelude::*;
+
+use acvm::{AcirField, FieldElement};
+
+use crate::{
+    input_parser::InputValue, Abi, AbiParameter, AbiReturnType, AbiType, AbiVisibility, InputMap,
+    Sign,
+};
+use std::collections::{BTreeMap, HashSet};
+
+pub(super) use proptest_derive::Arbitrary;
+
+/// Mutates an iterator of mutable references to [`String`]s to ensure that all values are unique.
+fn ensure_unique_strings<'a>(iter: impl Iterator<Item = &'a mut String>) {
+    let mut seen_values: HashSet<String> = HashSet::default();
+    for value in iter {
+        while seen_values.contains(value.as_str()) {
+            value.push('1');
+        }
+        seen_values.insert(value.clone());
+    }
+}
+
+proptest::prop_compose! {
+    pub(super) fn arb_field_from_integer(bit_size: u32)(value: u128)-> FieldElement {
+        let width = (bit_size % 128).clamp(1, 127);
+        let max_value = 2u128.pow(width) - 1;
+        FieldElement::from(value.clamp(0, max_value))
+    }
+}
+
+fn arb_value_from_abi_type(abi_type: &AbiType) -> SBoxedStrategy<InputValue> {
+    match abi_type {
+        AbiType::Field => vec(any::<u8>(), 32)
+            .prop_map(|bytes| InputValue::Field(FieldElement::from_be_bytes_reduce(&bytes)))
+            .sboxed(),
+        AbiType::Integer { width, .. } => {
+            arb_field_from_integer(*width).prop_map(InputValue::Field).sboxed()
+        }
+
+        AbiType::Boolean => {
+            any::<bool>().prop_map(|val| InputValue::Field(FieldElement::from(val))).sboxed()
+        }
+
+        AbiType::String { length } => {
+            // Strings only allow ASCII characters as each character must be able to be represented by a single byte.
+            let string_regex = format!("[[:ascii:]]{{{length}}}");
+            proptest::string::string_regex(&string_regex)
+                .expect("parsing of regex should always succeed")
+                .prop_map(InputValue::String)
+                .sboxed()
+        }
+        AbiType::Array { length, typ } => {
+            let length = *length as usize;
+            let elements = vec(arb_value_from_abi_type(typ), length..=length);
+
+            elements.prop_map(InputValue::Vec).sboxed()
+        }
+
+        AbiType::Struct { fields, .. } => {
+            let fields: Vec<SBoxedStrategy<(String, InputValue)>> = fields
+                .iter()
+                .map(|(name, typ)| (Just(name.clone()), arb_value_from_abi_type(typ)).sboxed())
+                .collect();
+
+            fields
+                .prop_map(|fields| {
+                    let fields: BTreeMap<_, _> = fields.into_iter().collect();
+                    InputValue::Struct(fields)
+                })
+                .sboxed()
+        }
+
+        AbiType::Tuple { fields } => {
+            let fields: Vec<_> = fields.iter().map(arb_value_from_abi_type).collect();
+            fields.prop_map(InputValue::Vec).sboxed()
+        }
+    }
+}
+
+fn arb_primitive_abi_type() -> SBoxedStrategy<AbiType> {
+    const MAX_STRING_LEN: u32 = 1000;
+    proptest::prop_oneof![
+        Just(AbiType::Field),
+        Just(AbiType::Boolean),
+        any::<(Sign, u32)>().prop_map(|(sign, width)| {
+            let width = (width % 128).clamp(1, 127);
+            AbiType::Integer { sign, width }
+        }),
+        // restrict length of strings to avoid running out of memory
+        (1..MAX_STRING_LEN).prop_map(|length| AbiType::String { length }),
+    ]
+    .sboxed()
+}
+
+pub(super) fn arb_abi_type() -> BoxedStrategy<AbiType> {
+    let leaf = arb_primitive_abi_type();
+
+    leaf.prop_recursive(
+        8,   // up to 8 levels deep
+        256, // Shoot for maximum size of 256 nodes
+        10,  // We put up to 10 items per collection
+        |inner| {
+            prop_oneof![
+                (1..10u32, inner.clone())
+                    .prop_map(|(length, typ)| { AbiType::Array { length, typ: Box::new(typ) } })
+                    .boxed(),
+                prop::collection::vec(inner.clone(), 1..10)
+                    .prop_map(|fields| { AbiType::Tuple { fields } })
+                    .boxed(),
+                (".*", prop::collection::vec((".+", inner), 1..10))
+                    .prop_map(|(path, mut fields)| {
+                        // Require that all field names are unique.
+                        ensure_unique_strings(fields.iter_mut().map(|(field_name, _)| field_name));
+                        AbiType::Struct { path, fields }
+                    })
+                    .boxed(),
+            ]
+        },
+    )
+    .boxed()
+}
+
+fn arb_abi_param_and_value() -> BoxedStrategy<(AbiParameter, InputValue)> {
+    arb_abi_type()
+        .prop_flat_map(|typ| {
+            let value = arb_value_from_abi_type(&typ);
+            let param = arb_abi_param(typ);
+            (param, value)
+        })
+        .boxed()
+}
+
+fn arb_abi_param(typ: AbiType) -> SBoxedStrategy<AbiParameter> {
+    (".+", any::<AbiVisibility>())
+        .prop_map(move |(name, visibility)| AbiParameter { name, typ: typ.clone(), visibility })
+        .sboxed()
+}
+
+prop_compose! {
+    pub(super) fn arb_abi_and_input_map()
+        (mut parameters_with_values in proptest::collection::vec(arb_abi_param_and_value(), 0..100), return_type: Option<AbiReturnType>)
+        -> (Abi, InputMap) {
+            // Require that all parameter names are unique.
+            ensure_unique_strings(parameters_with_values.iter_mut().map(|(param_name,_)| &mut param_name.name));
+
+            let parameters  = vecmap(&parameters_with_values, |(param, _)| param.clone());
+            let input_map = btree_map(parameters_with_values, |(param, value)| (param.name, value));
+
+            (Abi { parameters, return_type, error_types: BTreeMap::default() }, input_map)
+    }
+}

tooling/noirc_abi/src/lib.rs

@@ -25,6 +25,9 @@ use std::{collections::BTreeMap, str};
 //
 // This ABI has nothing to do with ACVM or ACIR. Although they implicitly have a relationship
 
+#[cfg(test)]
+mod arbitrary;
+
 pub mod errors;
 pub mod input_parser;
 mod serialization;
@@ -75,6 +78,7 @@ pub enum AbiType {
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(test, derive(arbitrary::Arbitrary))]
 #[serde(rename_all = "lowercase")]
 /// Represents whether the parameter is public or known only to the prover.
 pub enum AbiVisibility {
@@ -86,6 +90,7 @@ pub enum AbiVisibility {
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[cfg_attr(test, derive(arbitrary::Arbitrary))]
 #[serde(rename_all = "lowercase")]
 pub enum Sign {
     Unsigned,
@@ -142,10 +147,12 @@ impl From<&AbiType> for PrintableType {
 }
 
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[cfg_attr(test, derive(arbitrary::Arbitrary))]
 /// An argument or return value of the circuit's `main` function.
 pub struct AbiParameter {
     pub name: String,
     #[serde(rename = "type")]
+    #[cfg_attr(test, proptest(strategy = "arbitrary::arb_abi_type()"))]
     pub typ: AbiType,
     pub visibility: AbiVisibility,
 }
@@ -157,16 +164,20 @@ impl AbiParameter {
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
+#[cfg_attr(test, derive(arbitrary::Arbitrary))]
 pub struct AbiReturnType {
+    #[cfg_attr(test, proptest(strategy = "arbitrary::arb_abi_type()"))]
     pub abi_type: AbiType,
     pub visibility: AbiVisibility,
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
+#[cfg_attr(test, derive(arbitrary::Arbitrary))]
 pub struct Abi {
     /// An ordered list of the arguments to the program's `main` function, specifying their types and visibility.
     pub parameters: Vec<AbiParameter>,
     pub return_type: Option<AbiReturnType>,
+    #[cfg_attr(test, proptest(strategy = "proptest::prelude::Just(BTreeMap::from([]))"))]
     pub error_types: BTreeMap<ErrorSelector, AbiErrorType>,
 }
 
@@ -488,56 +499,18 @@ pub fn display_abi_error<F: AcirField>(
 
 #[cfg(test)]
 mod test {
-    use std::collections::BTreeMap;
-
-    use acvm::{AcirField, FieldElement};
+    use proptest::prelude::*;
 
-    use crate::{
-        input_parser::InputValue, Abi, AbiParameter, AbiReturnType, AbiType, AbiVisibility,
-        InputMap,
-    };
+    use crate::arbitrary::arb_abi_and_input_map;
 
-    #[test]
-    fn witness_encoding_roundtrip() {
-        let abi = Abi {
-            parameters: vec![
-                AbiParameter {
-                    name: "thing1".to_string(),
-                    typ: AbiType::Array { length: 2, typ: Box::new(AbiType::Field) },
-                    visibility: AbiVisibility::Public,
-                },
-                AbiParameter {
-                    name: "thing2".to_string(),
-                    typ: AbiType::Field,
-                    visibility: AbiVisibility::Public,
-                },
-            ],
-            return_type: Some(AbiReturnType {
-                abi_type: AbiType::Field,
-                visibility: AbiVisibility::Public,
-            }),
-            error_types: BTreeMap::default(),
-        };
+    proptest! {
+        #[test]
+        fn encoding_and_decoding_returns_original_witness_map((abi, input_map) in arb_abi_and_input_map()) {
+            let witness_map = abi.encode(&input_map, None).unwrap();
+            let (decoded_inputs, return_value) = abi.decode(&witness_map).unwrap();
 
-        // Note we omit return value from inputs
-        let inputs: InputMap = BTreeMap::from([
-            (
-                "thing1".to_string(),
-                InputValue::Vec(vec![
-                    InputValue::Field(FieldElement::one()),
-                    InputValue::Field(FieldElement::one()),
-                ]),
-            ),
-            ("thing2".to_string(), InputValue::Field(FieldElement::zero())),
-        ]);
-
-        let witness_map = abi.encode(&inputs, None).unwrap();
-        let (reconstructed_inputs, return_value) = abi.decode(&witness_map).unwrap();
-
-        for (key, expected_value) in inputs {
-            assert_eq!(reconstructed_inputs[&key], expected_value);
+            prop_assert_eq!(decoded_inputs, input_map);
+            prop_assert_eq!(return_value, None);
         }
-
-        assert!(return_value.is_none());
     }
 }