Test rust-produced domain hashes

solidity/core/contracts/validator-manager/MultisigValidatorManager.sol

@@ -65,7 +65,7 @@ abstract contract MultisigValidatorManager is Ownable {
     ) Ownable() {
         // Set immutables.
         outboxDomain = _outboxDomain;
-        outboxDomainHash = keccak256(abi.encodePacked(_outboxDomain, "ABACUS"));
+        outboxDomainHash = domainHash(_outboxDomain);
 
         // Enroll validators. Reverts if there are any duplicates.
         uint256 _validatorSetLength = _validatorSet.length;
@@ -166,6 +166,14 @@ abstract contract MultisigValidatorManager is Ownable {
         return _validatorSignatureCount >= quorumThreshold;
     }
 
+    /**
+     * @notice Hash of domain concatenated with "ABACUS".
+     * @param _domain The domain to hash.
+     */
+    function domainHash(uint32 _domain) public pure returns (bytes32) {
+        return keccak256(abi.encodePacked(_domain, "ABACUS"));
+    }
+
     // ============ Internal Functions ============
 
     /**

solidity/core/test/validator-manager/multisigValidatorManager.test.ts

@@ -15,6 +15,8 @@ const OUTBOX_DOMAIN_HASH = ethers.utils.keccak256(
 );
 const QUORUM_THRESHOLD = 1;
 
+const domainHashTestCases = require('../../../vectors/domainHash.json');
+
 describe('MultisigValidatorManager', async () => {
   let validatorManager: TestMultisigValidatorManager,
     signer: SignerWithAddress,
@@ -232,4 +234,18 @@ describe('MultisigValidatorManager', async () => {
       ).to.be.revertedWith('!sorted signers');
     });
   });
+
+  describe('#domainHash', () => {
+    it('matches Rust-produced domain hashes', async () => {
+      // Compare Rust output in json file to solidity output (json file matches
+      // hash for local domain of 1000)
+      for (let testCase of domainHashTestCases) {
+        const { expectedDomainHash } = testCase;
+        const domainHash = await validatorManager.domainHash(
+          testCase.outboxDomain,
+        );
+        expect(domainHash).to.equal(expectedDomainHash);
+      }
+    });
+  });
 });