add optional field, use it on one test

Cargo.lock

@@ -1832,7 +1832,7 @@ dependencies = [
 
 [[package]]
 name = "zokrates_test"
-version = "0.1.1"
+version = "0.1.0"
 dependencies = [
  "fs_extra",
  "glob 0.3.0",

zokrates_core_test/tests/tests/spread_slice.json

@@ -1,5 +1,6 @@
 {
 	"entry_point": "./tests/tests/spread_slice.zok",
+	"max_constraint_count": 9,
 	"tests": [
 		{
 			"input": {

zokrates_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "zokrates_test"
-version = "0.1.1"
+version = "0.1.0"
 authors = ["schaeff <thibaut@schaeff.fr>"]
 edition = "2018"
 

zokrates_test/src/lib.rs

@@ -8,6 +8,7 @@ use zokrates_field::field::{Field, FieldPrime};
 #[derive(Serialize, Deserialize)]
 struct Tests {
     pub entry_point: PathBuf,
+    pub max_constraint_count: Option<usize>,
     pub tests: Vec<Test>,
 }
 
@@ -34,6 +35,18 @@ struct Output {
 
 type Val = String;
 
+fn parse_val<T: Field>(s: String) -> T {
+    let s = if s.starts_with("0x") {
+        u32::from_str_radix(s.trim_start_matches("0x"), 16)
+            .unwrap()
+            .to_string()
+    } else {
+        s
+    };
+
+    T::try_from_dec_str(&s).unwrap()
+}
+
 impl From<ir::ExecutionResult<FieldPrime>> for ComparableResult {
     fn from(r: ir::ExecutionResult<FieldPrime>) -> ComparableResult {
         ComparableResult(r.map(|v| v.return_values()))
@@ -42,12 +55,7 @@ impl From<ir::ExecutionResult<FieldPrime>> for ComparableResult {
 
 impl From<TestResult> for ComparableResult {
     fn from(r: TestResult) -> ComparableResult {
-        ComparableResult(r.map(|v| {
-            v.values
-                .iter()
-                .map(|v| FieldPrime::try_from_dec_str(v).unwrap())
-                .collect()
-        }))
+        ComparableResult(r.map(|v| v.values.into_iter().map(parse_val).collect()))
     }
 }
 
@@ -81,14 +89,21 @@ pub fn test_inner(test_path: &str) {
 
     let bin = artifacts.prog();
 
+    match t.max_constraint_count {
+        Some(count) => assert!(
+            bin.constraint_count() <= count,
+            "Expected at the most {} constraints, found {}:\n{}",
+            count,
+            bin.constraint_count(),
+            bin
+        ),
+        _ => {}
+    };
+
     for test in t.tests.into_iter() {
         let input = &test.input.values;
-        let output = bin.execute(
-            &input
-                .iter()
-                .map(|v| FieldPrime::try_from_dec_str(&v.clone()).unwrap())
-                .collect(),
-        );
+
+        let output = bin.execute(&(input.iter().cloned().map(parse_val).collect()));
 
         match compare(output, test.output) {
             Err(e) => {