interop testing of hashing of empty private call stack item

yarn-project/circuits.js/src/structs/__snapshots__/private_call_stack_item.test.ts.snap

@@ -0,0 +1,44 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`PrivateCallStackItem computes empty item hash 1`] = `
+Fr {
+  "asBigInt": 2538825319674219123846958071590111740225106671201233263868844578355336664781n,
+  "asBuffer": {
+    "data": [
+      5,
+      156,
+      236,
+      152,
+      233,
+      157,
+      232,
+      67,
+      153,
+      229,
+      27,
+      168,
+      75,
+      195,
+      183,
+      254,
+      111,
+      10,
+      250,
+      64,
+      122,
+      141,
+      166,
+      174,
+      48,
+      176,
+      125,
+      64,
+      205,
+      67,
+      86,
+      205,
+    ],
+    "type": "Buffer",
+  },
+}
+`;

yarn-project/circuits.js/src/structs/private_call_stack_item.test.ts

@@ -3,34 +3,43 @@ import { makePrivateCallStackItem } from '../tests/factories.js';
 import { PrivateCallStackItem } from './private_call_stack_item.js';
 
 describe('PrivateCallStackItem', () => {
-  let inputs: PrivateCallStackItem;
+  let item: PrivateCallStackItem;
 
   beforeAll(() => {
     const randomInt = Math.floor(Math.random() * 1000);
-    inputs = makePrivateCallStackItem(randomInt);
+    item = makePrivateCallStackItem(randomInt);
   });
 
   it('serializes to buffer and deserializes it back', () => {
-    const buffer = inputs.toBuffer();
+    const buffer = item.toBuffer();
     const res = PrivateCallStackItem.fromBuffer(buffer);
-    expect(res).toEqual(inputs);
+    expect(res).toEqual(item);
   });
 
   it('serializes to field array and deserializes it back', () => {
-    const fieldArray = inputs.toFields();
+    const fieldArray = item.toFields();
     const res = PrivateCallStackItem.fromFields(fieldArray);
-    expect(res).toEqual(inputs);
+    expect(res).toEqual(item);
   });
 
   it('number of fields matches constant', () => {
-    const fields = inputs.toFields();
+    const fields = item.toFields();
     expect(fields.length).toBe(PRIVATE_CALL_STACK_ITEM_LENGTH);
   });
 
   it('computes hash', () => {
     const seed = 9870243;
-    const PrivateCallStackItem = makePrivateCallStackItem(seed);
-    const hash = PrivateCallStackItem.hash();
+    const item = makePrivateCallStackItem(seed);
+    const hash = item.hash();
     expect(hash).toMatchSnapshot();
   });
+
+  it('computes empty item hash', () => {
+    const item = PrivateCallStackItem.empty();
+    const hash = item.hash();
+    expect(hash).toMatchSnapshot();
+
+    // Value used in empty_hash test in private_call_stack_item.nr
+    // console.log("hash", hash.toString());
+  });
 });

yarn-project/noir-protocol-circuits/src/crates/types/src/abis/private_call_stack_item.nr

@@ -75,7 +75,11 @@ fn serialization_smoke() {
 }
 
 #[test]
-fn hash_smoke() {
-    let item: PrivateCallStackItem = dep::std::unsafe::zeroed();
-    let _hashed = item.hash();
+fn empty_hash() {
+    let mut item: PrivateCallStackItem = dep::std::unsafe::zeroed();
+    item.function_data.is_private = true;
+    let hash = item.hash();
+
+    // Value from private_call_stack_item.test.ts "computes empty item hash" test
+    assert_eq(hash, 0x059cec98e99de84399e51ba84bc3b7fe6f0afa407a8da6ae30b07d40cd4356cd);
 }