Unit test for UpdateCoins UTXO creation.

Add a unit test (together with the necessary framework around) for
UTXO creation from UpdateCoins, based on the UTXO hasher (rather than
the txid directly).

Author: domob1812

divi/src/Makefile.test.include

@@ -63,6 +63,7 @@ BITCOIN_TESTS =\
   test/MockBlockIncentivesPopulator.h \
   test/MockBlockSubsidyProvider.h \
   test/MockPoSStakeModifierService.h \
+  test/MockUtxoHasher.cpp \
   test/MockVaultManagerDatabase.h \
   test/Monthlywalletbackupcreator_tests.cpp \
   test/ActiveMasternode_tests.cpp \
@@ -102,6 +103,7 @@ BITCOIN_TESTS =\
   test/PoSStakeModifierService_tests.cpp \
   test/LegacyPoSStakeModifierService_tests.cpp \
   test/LotteryWinnersCalculatorTests.cpp \
+  test/UtxoCheckingAndUpdating_tests.cpp \
   test/VaultManager_tests.cpp \
   test/multi_wallet_tests.cpp \
   test/MockSignatureSizeEstimator.h \

divi/src/test/MockUtxoHasher.cpp

@@ -0,0 +1,21 @@
+#include "MockUtxoHasher.h"
+
+#include "hash.h"
+#include "primitives/transaction.h"
+
+uint256 MockUtxoHasher::Add(const CTransaction& tx)
+{
+  ++cnt;
+  const uint256 value = Hash(&cnt, (&cnt) + 1);
+  customHashes.emplace(tx.GetHash(), value);
+  return value;
+}
+
+uint256 MockUtxoHasher::GetUtxoHash(const CTransaction& tx) const
+{
+  const uint256 txid = tx.GetHash();
+  const auto mit = customHashes.find(txid);
+  if (mit != customHashes.end())
+    return mit->second;
+  return txid;
+}

divi/src/test/MockUtxoHasher.h

@@ -0,0 +1,39 @@
+#ifndef MOCKUTXOHASHER_H
+#define MOCKUTXOHASHER_H
+
+#include "UtxoCheckingAndUpdating.h"
+
+#include "uint256.h"
+
+#include <map>
+
+class CTransaction;
+
+/** A TransactionUtxoHasher instance that returns normal txid's (as per before
+ *  segwit-light) by default, but can be instructed to return custom hashes
+ *  for certain transactions.  */
+class MockUtxoHasher : public TransactionUtxoHasher
+{
+
+private:
+
+  /** Custom hashes to return for given txid's.  */
+  std::map<uint256, uint256> customHashes;
+
+  /** Internal counter to produce unique fake hashes.  */
+  unsigned cnt = 0;
+
+public:
+
+  MockUtxoHasher()
+  {}
+
+  /** Marks the given transaction for returning a custom hash.  The hash
+   *  is generated uniquely and returned from the function.  */
+  uint256 Add(const CTransaction& tx);
+
+  uint256 GetUtxoHash(const CTransaction& tx) const override;
+
+};
+
+#endif // MOCKUTXOHASHER_H

divi/src/test/UtxoCheckingAndUpdating_tests.cpp

@@ -0,0 +1,54 @@
+#include <test_only.h>
+#include <UtxoCheckingAndUpdating.h>
+
+#include "coins.h"
+#include "MockUtxoHasher.h"
+#include "primitives/transaction.h"
+
+namespace
+{
+
+class UpdateCoinsTestFixture
+{
+
+private:
+
+  /** Empty coins used as base in the cached view.  */
+  CCoinsView dummyCoins;
+
+protected:
+
+  CCoinsViewCache coins;
+  MockUtxoHasher utxoHasher;
+
+  UpdateCoinsTestFixture()
+    : coins(&dummyCoins)
+  {}
+
+};
+
+BOOST_FIXTURE_TEST_SUITE(UpdateCoins_tests, UpdateCoinsTestFixture)
+
+BOOST_AUTO_TEST_CASE(addsCorrectOutputs)
+{
+  CMutableTransaction mtx;
+  mtx.vout.emplace_back(1, CScript() << OP_TRUE);
+  const CTransaction tx1(mtx);
+
+  mtx.vout.clear();
+  mtx.vout.emplace_back(2, CScript() << OP_TRUE);
+  const CTransaction tx2(mtx);
+  const auto id2 = utxoHasher.Add(tx2);
+
+  CTxUndo txundo;
+  UpdateCoins(tx1, coins, txundo, utxoHasher, 101);
+  UpdateCoins(tx2, coins, txundo, utxoHasher, 102);
+
+  BOOST_CHECK(coins.HaveCoins(tx1.GetHash()));
+  BOOST_CHECK(!coins.HaveCoins(tx2.GetHash()));
+  BOOST_CHECK(coins.HaveCoins(id2));
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // anonymous namespace