Merge #12516: Avoid unintentional unsigned integer wraparounds in tests

2736c9e05 Avoid unintentional unsigned integer wraparounds in tests (practicalswift)

Pull request description:

  Avoid unintentional unsigned integer wraparounds in tests.

  This is a subset of #11535 as suggested by @MarcoFalke :-)

Tree-SHA512: 4f4ee8a08870101a3f7451aefa77ae06aaf44e3c3b2f7555faa2b8a8503f97f34e34dffcf65154278f15767dc9823955f52d1aa7b39930b390e57cdf2b65e0f3

src/wallet/test/accounting_tests.cpp

@@ -82,7 +82,7 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
     wtx.mapValue["comment"] = "y";
     {
         CMutableTransaction tx(*wtx.tx);
-        --tx.nLockTime;  // Just to change the hash :)
+        ++tx.nLockTime;  // Just to change the hash :)
         wtx.SetTx(MakeTransactionRef(std::move(tx)));
     }
     pwalletMain->AddToWallet(wtx);
@@ -92,7 +92,7 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
     wtx.mapValue["comment"] = "x";
     {
         CMutableTransaction tx(*wtx.tx);
-        --tx.nLockTime;  // Just to change the hash :)
+        ++tx.nLockTime;  // Just to change the hash :)
         wtx.SetTx(MakeTransactionRef(std::move(tx)));
     }
     pwalletMain->AddToWallet(wtx);