chore(host-contracts): adding failing test to show edge case bug in mocked relayer

Author: jatZama

host-contracts/examples/TestAsyncDecryptMultiple.sol

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: BSD-3-Clause-Clear
+
+pragma solidity ^0.8.24;
+
+import "../lib/FHE.sol";
+import {CoprocessorSetup} from "../lib/CoprocessorSetup.sol";
+
+/// @notice First contract for testing asynchronous decryption via multiple contracts
+contract TestAsyncDecryptA {
+    euint64 xUint64;
+    uint64 public yUint64;
+
+    constructor() {
+        FHE.setCoprocessor(CoprocessorSetup.defaultConfig());
+        xUint64 = FHE.asEuint64(424242);
+        FHE.allowThis(xUint64);
+    }
+
+    function requestUint64() public {
+        bytes32[] memory cts = new bytes32[](1);
+        cts[0] = FHE.toBytes32(xUint64);
+        FHE.requestDecryption(cts, this.callbackUint64.selector);
+    }
+
+    function callbackUint64(uint256 requestID, bytes memory cleartexts, bytes memory decryptionProof) public {
+        FHE.checkSignatures(requestID, cleartexts, decryptionProof);
+        uint64 decryptedInput = abi.decode(cleartexts, (uint64));
+        yUint64 = decryptedInput;
+        revert();
+    }
+}
+
+/// @notice Second contract for testing asynchronous decryption via multiple contracts
+contract TestAsyncDecryptB {
+    euint64 xUint64;
+    uint64 public yUint64;
+
+    constructor() {
+        FHE.setCoprocessor(CoprocessorSetup.defaultConfig());
+        xUint64 = FHE.asEuint64(373737);
+        FHE.allowThis(xUint64);
+    }
+
+    function requestUint64() public {
+        bytes32[] memory cts = new bytes32[](1);
+        cts[0] = FHE.toBytes32(xUint64);
+        FHE.requestDecryption(cts, this.callbackUint64.selector);
+    }
+
+    function callbackUint64(uint256 requestID, bytes memory cleartexts, bytes memory decryptionProof) public {
+        FHE.checkSignatures(requestID, cleartexts, decryptionProof);
+        uint64 decryptedInput = abi.decode(cleartexts, (uint64));
+        yUint64 = decryptedInput;
+    }
+}

host-contracts/test/gatewayDecrypt/testAsyncDecryptMulti.ts

@@ -0,0 +1,42 @@
+import { expect } from 'chai';
+import { ethers, network } from 'hardhat';
+
+import { awaitAllDecryptionResults, initDecryptionOracle } from '../asyncDecrypt';
+import { createInstances } from '../instance';
+import { getSigners, initSigners } from '../signers';
+
+describe.only('TestAsyncDecryptMultiContracts', function () {
+  before(async function () {
+    await initSigners(2);
+    this.signers = await getSigners();
+    this.instances = await createInstances(this.signers);
+    await initDecryptionOracle();
+  });
+
+  beforeEach(async function () {
+    const contractFactoryA = await ethers.getContractFactory('TestAsyncDecryptA');
+    this.contractA = await contractFactoryA.connect(this.signers.alice).deploy();
+    await this.contractA.waitForDeployment();
+    const contractFactoryB = await ethers.getContractFactory('TestAsyncDecryptB');
+    this.contractB = await contractFactoryB.connect(this.signers.alice).deploy();
+    await this.contractB.waitForDeployment();
+    this.instances = await createInstances(this.signers);
+  });
+
+  it('test async decrypt euint64 via 2 contracts', async function () {
+    const tx = await this.contractA.connect(this.signers.carol).requestUint64();
+    await tx.wait();
+    try {
+      await awaitAllDecryptionResults();
+    } catch {
+      // we expect an error after first decryption, due to the revert in callback, so we silence it
+    }
+    const tx2 = await this.contractB.connect(this.signers.carol).requestUint64();
+    await tx2.wait();
+    await awaitAllDecryptionResults();
+    const y = await this.contractA.yUint64();
+    const y2 = await this.contractB.yUint64();
+    expect(y).to.equal(0); // because first decryption callback reverted
+    expect(y2).to.equal(373737); // this second decryption, on the other hand, should succeed, but currently it is not fulfilled by mocked mode due to a logic bug in mocked relayer
+  });
+});