Use sha256 for the MerkleProof custom hash tests

Author: Amxx

contracts/mocks/MerkleProofCustomHashMock.sol

@@ -7,7 +7,7 @@ import {MerkleProof} from "../utils/cryptography/MerkleProof.sol";
 // This could be a library, but then we would have to add it to the Stateless.sol mock for upgradeable tests
 abstract contract MerkleProofCustomHashMock {
     function customHash(bytes32 a, bytes32 b) internal pure returns (bytes32) {
-        return a < b ? keccak256(abi.encode(bytes32(0), a, b)) : keccak256(abi.encode(bytes32(0), b, a));
+        return a < b ? sha256(abi.encode(a, b)) : sha256(abi.encode(b, a));
     }
 
     function verify(bytes32[] calldata proof, bytes32 root, bytes32 leaf) internal view returns (bool) {

test/utils/cryptography/MerkleProof.test.js

@@ -6,9 +6,9 @@ const { SimpleMerkleTree } = require('@openzeppelin/merkle-tree');
 // generate bytes32 leaves from a string
 const toLeaves = (str, separator = '') => str.split(separator).map(e => ethers.keccak256(ethers.toUtf8Bytes(e)));
 // internal node hashes
-const hashSorted = (...elements) => ethers.keccak256(Buffer.concat(elements.map(ethers.getBytes).sort(Buffer.compare)));
-const defaultHash = (a, b) => hashSorted(a, b);
-const customHash = (a, b) => hashSorted(ethers.ZeroHash, a, b);
+const concatSorted = (...elements) => Buffer.concat(elements.map(ethers.getBytes).sort(Buffer.compare));
+const defaultHash = (a, b) => ethers.keccak256(concatSorted(a, b));
+const customHash = (a, b) => ethers.sha256(concatSorted(a, b));
 
 describe('MerkleProof', function () {
   for (const { title, contractName, nodeHash } of [