Fix linting errors

contracts/exchange/contracts/src/MixinTransactions.sol

@@ -86,6 +86,7 @@ contract MixinTransactions is
         bytes32 transactionHash = getTransactionHash(transaction);
 
         // Check transaction is not expired
+        // solhint-disable-next-line not-rely-on-time
         if (block.timestamp >= transaction.expirationTimeSeconds) {
             _rrevert(TransactionError(
                 TransactionErrorCodes.EXPIRED,

contracts/exchange/test/transactions.ts

@@ -1023,7 +1023,7 @@ describe('Exchange transactions', () => {
                     ExchangeRevertErrors.TransactionErrorCode.Expired,
                     expiredTransactionHash,
                 );
-                expect(tx).to.revertWith(expectedError);
+                return expect(tx).to.revertWith(expectedError);
             });
         });
         describe('examples', () => {