diff --git a/src/test/coins_tests.cpp b/src/test/coins_tests.cpp
index 9de78fdcd..fec8687cf 100644
--- a/src/test/coins_tests.cpp
+++ b/src/test/coins_tests.cpp
@@ -1,914 +1,914 @@
 // Copyright (c) 2014-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <coins.h>
 
 #include <clientversion.h>
 #include <consensus/validation.h>
 #include <script/standard.h>
 #include <streams.h>
 #include <uint256.h>
 #include <undo.h>
 #include <util/strencodings.h>
 #include <validation.h>
 
 #include <test/test_bitcoin.h>
 
 #include <boost/test/unit_test.hpp>
 
 #include <map>
 #include <vector>
 
 namespace {
 
 //! equality test
 bool operator==(const Coin &a, const Coin &b) {
     // Empty Coin objects are always equal.
     if (a.IsSpent() && b.IsSpent()) {
         return true;
     }
 
     return a.IsCoinBase() == b.IsCoinBase() && a.GetHeight() == b.GetHeight() &&
            a.GetTxOut() == b.GetTxOut();
 }
 
 class CCoinsViewTest : public CCoinsView {
     uint256 hashBestBlock_;
     std::map<COutPoint, Coin> map_;
 
 public:
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override {
         std::map<COutPoint, Coin>::const_iterator it = map_.find(outpoint);
         if (it == map_.end()) {
             return false;
         }
         coin = it->second;
         if (coin.IsSpent() && InsecureRandBool() == 0) {
             // Randomly return false in case of an empty entry.
             return false;
         }
         return true;
     }
 
     uint256 GetBestBlock() const override { return hashBestBlock_; }
 
     bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) override {
         for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
             if (it->second.flags & CCoinsCacheEntry::DIRTY) {
                 // Same optimization used in CCoinsViewDB is to only write dirty
                 // entries.
                 map_[it->first] = it->second.coin;
                 if (it->second.coin.IsSpent() && InsecureRandRange(3) == 0) {
                     // Randomly delete empty entries on write.
                     map_.erase(it->first);
                 }
             }
             mapCoins.erase(it++);
         }
         if (!hashBlock.IsNull()) {
             hashBestBlock_ = hashBlock;
         }
         return true;
     }
 };
 
 class CCoinsViewCacheTest : public CCoinsViewCache {
 public:
     explicit CCoinsViewCacheTest(CCoinsView *_base) : CCoinsViewCache(_base) {}
 
     void SelfTest() const {
         // Manually recompute the dynamic usage of the whole data, and compare
         // it.
         size_t ret = memusage::DynamicUsage(cacheCoins);
         size_t count = 0;
         for (const auto &entry : cacheCoins) {
             ret += entry.second.coin.DynamicMemoryUsage();
             count++;
         }
         BOOST_CHECK_EQUAL(GetCacheSize(), count);
         BOOST_CHECK_EQUAL(DynamicMemoryUsage(), ret);
     }
 
     CCoinsMap &map() const { return cacheCoins; }
     size_t &usage() const { return cachedCoinsUsage; }
 };
 } // namespace
 
 BOOST_FIXTURE_TEST_SUITE(coins_tests, BasicTestingSetup)
 
 static const unsigned int NUM_SIMULATION_ITERATIONS = 40000;
 
 // This is a large randomized insert/remove simulation test on a variable-size
 // stack of caches on top of CCoinsViewTest.
 //
 // It will randomly create/update/delete Coin entries to a tip of caches, with
 // txids picked from a limited list of random 256-bit hashes. Occasionally, a
 // new tip is added to the stack of caches, or the tip is flushed and removed.
 //
 // During the process, booleans are kept to make sure that the randomized
 // operation hits all branches.
 BOOST_AUTO_TEST_CASE(coins_cache_simulation_test) {
     // Various coverage trackers.
     bool removed_all_caches = false;
     bool reached_4_caches = false;
     bool added_an_entry = false;
     bool added_an_unspendable_entry = false;
     bool removed_an_entry = false;
     bool updated_an_entry = false;
     bool found_an_entry = false;
     bool missed_an_entry = false;
     bool uncached_an_entry = false;
 
     // A simple map to track what we expect the cache stack to represent.
     std::map<COutPoint, Coin> result;
 
     // The cache stack.
     // A CCoinsViewTest at the bottom.
     CCoinsViewTest base;
     // A stack of CCoinsViewCaches on top.
     std::vector<CCoinsViewCacheTest *> stack;
     // Start with one cache.
     stack.push_back(new CCoinsViewCacheTest(&base));
 
     // Use a limited set of random transaction ids, so we do test overwriting
     // entries.
     std::vector<TxId> txids;
     txids.resize(NUM_SIMULATION_ITERATIONS / 8);
     for (size_t i = 0; i < txids.size(); i++) {
         txids[i] = TxId(InsecureRand256());
     }
 
     for (unsigned int i = 0; i < NUM_SIMULATION_ITERATIONS; i++) {
         // Do a random modification.
         {
             // txid we're going to modify in this iteration.
             const TxId txid = txids[InsecureRandRange(txids.size())];
             Coin &coin = result[COutPoint(txid, 0)];
             // Determine whether to test HaveCoin before or after Access* (or
             // both). As these functions can influence each other's behaviour by
             // pulling things into the cache, all combinations are tested.
             bool test_havecoin_before = InsecureRandBits(2) == 0;
             bool test_havecoin_after = InsecureRandBits(2) == 0;
 
             bool result_havecoin =
                 test_havecoin_before
                     ? stack.back()->HaveCoin(COutPoint(txid, 0))
                     : false;
             const Coin &entry =
                 (InsecureRandRange(500) == 0)
                     ? AccessByTxid(*stack.back(), txid)
                     : stack.back()->AccessCoin(COutPoint(txid, 0));
             BOOST_CHECK(coin == entry);
             BOOST_CHECK(!test_havecoin_before ||
                         result_havecoin == !entry.IsSpent());
 
             if (test_havecoin_after) {
                 bool ret = stack.back()->HaveCoin(COutPoint(txid, 0));
                 BOOST_CHECK(ret == !entry.IsSpent());
             }
 
             if (InsecureRandRange(5) == 0 || coin.IsSpent()) {
                 CTxOut txout;
                 txout.nValue = int64_t(InsecureRand32()) * SATOSHI;
                 if (InsecureRandRange(16) == 0 && coin.IsSpent()) {
                     txout.scriptPubKey.assign(1 + InsecureRandBits(6),
                                               OP_RETURN);
                     BOOST_CHECK(txout.scriptPubKey.IsUnspendable());
                     added_an_unspendable_entry = true;
                 } else {
                     // Random sizes so we can test memory usage accounting
                     txout.scriptPubKey.assign(InsecureRandBits(6), 0);
                     (coin.IsSpent() ? added_an_entry : updated_an_entry) = true;
                     coin = Coin(txout, 1, false);
                 }
 
                 Coin newcoin(txout, 1, false);
                 stack.back()->AddCoin(COutPoint(txid, 0), newcoin,
                                       !coin.IsSpent() || InsecureRand32() & 1);
             } else {
                 removed_an_entry = true;
                 coin.Clear();
                 stack.back()->SpendCoin(COutPoint(txid, 0));
             }
         }
 
         // One every 10 iterations, remove a random entry from the cache
         if (InsecureRandRange(10) == 0) {
             COutPoint out(txids[InsecureRand32() % txids.size()], 0);
             int cacheid = InsecureRand32() % stack.size();
             stack[cacheid]->Uncache(out);
             uncached_an_entry |= !stack[cacheid]->HaveCoinInCache(out);
         }
 
         // Once every 1000 iterations and at the end, verify the full cache.
         if (InsecureRandRange(1000) == 1 ||
             i == NUM_SIMULATION_ITERATIONS - 1) {
             for (const auto &entry : result) {
                 bool have = stack.back()->HaveCoin(entry.first);
                 const Coin &coin = stack.back()->AccessCoin(entry.first);
                 BOOST_CHECK(have == !coin.IsSpent());
                 BOOST_CHECK(coin == entry.second);
                 if (coin.IsSpent()) {
                     missed_an_entry = true;
                 } else {
                     BOOST_CHECK(stack.back()->HaveCoinInCache(entry.first));
                     found_an_entry = true;
                 }
             }
             for (const CCoinsViewCacheTest *test : stack) {
                 test->SelfTest();
             }
         }
 
         // Every 100 iterations, flush an intermediate cache
         if (InsecureRandRange(100) == 0) {
             if (stack.size() > 1 && InsecureRandBool() == 0) {
                 unsigned int flushIndex = InsecureRandRange(stack.size() - 1);
                 stack[flushIndex]->Flush();
             }
         }
         if (InsecureRandRange(100) == 0) {
             // Every 100 iterations, change the cache stack.
             if (stack.size() > 0 && InsecureRandBool() == 0) {
                 // Remove the top cache
                 stack.back()->Flush();
                 delete stack.back();
                 stack.pop_back();
             }
             if (stack.size() == 0 || (stack.size() < 4 && InsecureRandBool())) {
                 // Add a new cache
                 CCoinsView *tip = &base;
                 if (stack.size() > 0) {
                     tip = stack.back();
                 } else {
                     removed_all_caches = true;
                 }
                 stack.push_back(new CCoinsViewCacheTest(tip));
                 if (stack.size() == 4) {
                     reached_4_caches = true;
                 }
             }
         }
     }
 
     // Clean up the stack.
     while (stack.size() > 0) {
         delete stack.back();
         stack.pop_back();
     }
 
     // Verify coverage.
     BOOST_CHECK(removed_all_caches);
     BOOST_CHECK(reached_4_caches);
     BOOST_CHECK(added_an_entry);
     BOOST_CHECK(added_an_unspendable_entry);
     BOOST_CHECK(removed_an_entry);
     BOOST_CHECK(updated_an_entry);
     BOOST_CHECK(found_an_entry);
     BOOST_CHECK(missed_an_entry);
     BOOST_CHECK(uncached_an_entry);
 }
 
 // Store of all necessary tx and undo data for next test
 typedef std::map<COutPoint, std::tuple<CTransaction, CTxUndo, Coin>> UtxoData;
 UtxoData utxoData;
 
 UtxoData::iterator FindRandomFrom(const std::set<COutPoint> &utxoSet) {
     assert(utxoSet.size());
     auto utxoSetIt = utxoSet.lower_bound(COutPoint(TxId(InsecureRand256()), 0));
     if (utxoSetIt == utxoSet.end()) {
         utxoSetIt = utxoSet.begin();
     }
     auto utxoDataIt = utxoData.find(*utxoSetIt);
     assert(utxoDataIt != utxoData.end());
     return utxoDataIt;
 }
 
 // This test is similar to the previous test except the emphasis is on testing
 // the functionality of UpdateCoins random txs are created and UpdateCoins is
 // used to update the cache stack. In particular it is tested that spending a
 // duplicate coinbase tx has the expected effect (the other duplicate is
 // overwritten at all cache levels)
 BOOST_AUTO_TEST_CASE(updatecoins_simulation_test) {
     bool spent_a_duplicate_coinbase = false;
     // A simple map to track what we expect the cache stack to represent.
     std::map<COutPoint, Coin> result;
 
     // The cache stack.
     // A CCoinsViewTest at the bottom.
     CCoinsViewTest base;
     // A stack of CCoinsViewCaches on top.
     std::vector<CCoinsViewCacheTest *> stack;
     // Start with one cache.
     stack.push_back(new CCoinsViewCacheTest(&base));
 
     // Track the txids we've used in various sets
     std::set<COutPoint> coinbase_coins;
     std::set<COutPoint> disconnected_coins;
     std::set<COutPoint> duplicate_coins;
     std::set<COutPoint> utxoset;
 
     for (int64_t i = 0; i < NUM_SIMULATION_ITERATIONS; i++) {
         uint32_t randiter = InsecureRand32();
 
         // 19/20 txs add a new transaction
         if (randiter % 20 < 19) {
             CMutableTransaction tx;
             tx.vin.resize(1);
             tx.vout.resize(1);
             // Keep txs unique unless intended to duplicate.
             tx.vout[0].nValue = i * SATOSHI;
             // Random sizes so we can test memory usage accounting
             tx.vout[0].scriptPubKey.assign(InsecureRand32() & 0x3F, 0);
             unsigned int height = InsecureRand32();
             Coin old_coin;
 
             // 2/20 times create a new coinbase
             if (randiter % 20 < 2 || coinbase_coins.size() < 10) {
                 // 1/10 of those times create a duplicate coinbase
                 if (InsecureRandRange(10) == 0 && coinbase_coins.size()) {
                     auto utxod = FindRandomFrom(coinbase_coins);
                     // Reuse the exact same coinbase
                     tx = CMutableTransaction{std::get<0>(utxod->second)};
                     // shouldn't be available for reconnection if it's been
                     // duplicated
                     disconnected_coins.erase(utxod->first);
 
                     duplicate_coins.insert(utxod->first);
                 } else {
                     coinbase_coins.insert(COutPoint(tx.GetId(), 0));
                 }
                 assert(CTransaction(tx).IsCoinBase());
             }
 
             // 17/20 times reconnect previous or add a regular tx
             else {
 
                 COutPoint prevout;
                 // 1/20 times reconnect a previously disconnected tx
                 if (randiter % 20 == 2 && disconnected_coins.size()) {
                     auto utxod = FindRandomFrom(disconnected_coins);
                     tx = CMutableTransaction{std::get<0>(utxod->second)};
                     prevout = tx.vin[0].prevout;
                     if (!CTransaction(tx).IsCoinBase() &&
                         !utxoset.count(prevout)) {
                         disconnected_coins.erase(utxod->first);
                         continue;
                     }
 
                     // If this tx is already IN the UTXO, then it must be a
                     // coinbase, and it must be a duplicate
                     if (utxoset.count(utxod->first)) {
                         assert(CTransaction(tx).IsCoinBase());
                         assert(duplicate_coins.count(utxod->first));
                     }
                     disconnected_coins.erase(utxod->first);
                 }
 
                 // 16/20 times create a regular tx
                 else {
                     auto utxod = FindRandomFrom(utxoset);
                     prevout = utxod->first;
 
                     // Construct the tx to spend the coins of prevouthash
                     tx.vin[0].prevout = COutPoint(prevout.GetTxId(), 0);
                     assert(!CTransaction(tx).IsCoinBase());
                 }
 
                 // In this simple test coins only have two states, spent or
                 // unspent, save the unspent state to restore
                 old_coin = result[prevout];
                 // Update the expected result of prevouthash to know these coins
                 // are spent
                 result[prevout].Clear();
 
                 utxoset.erase(prevout);
 
                 // The test is designed to ensure spending a duplicate coinbase
                 // will work properly if that ever happens and not resurrect the
                 // previously overwritten coinbase
                 if (duplicate_coins.count(prevout)) {
                     spent_a_duplicate_coinbase = true;
                 }
             }
             // Update the expected result to know about the new output coins
             assert(tx.vout.size() == 1);
             const COutPoint outpoint(tx.GetId(), 0);
             result[outpoint] =
                 Coin(tx.vout[0], height, CTransaction(tx).IsCoinBase());
 
             // Call UpdateCoins on the top cache
             CTxUndo undo;
             UpdateCoins(*(stack.back()), CTransaction(tx), undo, height);
 
             // Update the utxo set for future spends
             utxoset.insert(outpoint);
 
             // Track this tx and undo info to use later
             utxoData.emplace(outpoint,
                              std::make_tuple(CTransaction(tx), undo, old_coin));
         }
 
         // 1/20 times undo a previous transaction
         else if (utxoset.size()) {
             auto utxod = FindRandomFrom(utxoset);
 
             CTransaction &tx = std::get<0>(utxod->second);
             CTxUndo &undo = std::get<1>(utxod->second);
             Coin &orig_coin = std::get<2>(utxod->second);
 
             // Update the expected result
             // Remove new outputs
             result[utxod->first].Clear();
             // If not coinbase restore prevout
             if (!tx.IsCoinBase()) {
                 result[tx.vin[0].prevout] = orig_coin;
             }
 
             // Disconnect the tx from the current UTXO
             // See code in DisconnectBlock
             // remove outputs
             stack.back()->SpendCoin(utxod->first);
 
             // restore inputs
             if (!tx.IsCoinBase()) {
                 const COutPoint &out = tx.vin[0].prevout;
                 UndoCoinSpend(undo.vprevout[0], *(stack.back()), out);
             }
 
             // Store as a candidate for reconnection
             disconnected_coins.insert(utxod->first);
 
             // Update the utxoset
             utxoset.erase(utxod->first);
             if (!tx.IsCoinBase()) {
                 utxoset.insert(tx.vin[0].prevout);
             }
         }
 
         // Once every 1000 iterations and at the end, verify the full cache.
         if (InsecureRandRange(1000) == 1 ||
             i == NUM_SIMULATION_ITERATIONS - 1) {
             for (const auto &entry : result) {
                 bool have = stack.back()->HaveCoin(entry.first);
                 const Coin &coin = stack.back()->AccessCoin(entry.first);
                 BOOST_CHECK(have == !coin.IsSpent());
                 BOOST_CHECK(coin == entry.second);
             }
         }
 
         // One every 10 iterations, remove a random entry from the cache
         if (utxoset.size() > 1 && InsecureRandRange(30) == 0) {
             stack[InsecureRand32() % stack.size()]->Uncache(
                 FindRandomFrom(utxoset)->first);
         }
         if (disconnected_coins.size() > 1 && InsecureRandRange(30) == 0) {
             stack[InsecureRand32() % stack.size()]->Uncache(
                 FindRandomFrom(disconnected_coins)->first);
         }
         if (duplicate_coins.size() > 1 && InsecureRandRange(30) == 0) {
             stack[InsecureRand32() % stack.size()]->Uncache(
                 FindRandomFrom(duplicate_coins)->first);
         }
 
         if (InsecureRandRange(100) == 0) {
             // Every 100 iterations, flush an intermediate cache
             if (stack.size() > 1 && InsecureRandBool() == 0) {
                 unsigned int flushIndex = InsecureRandRange(stack.size() - 1);
                 stack[flushIndex]->Flush();
             }
         }
         if (InsecureRandRange(100) == 0) {
             // Every 100 iterations, change the cache stack.
             if (stack.size() > 0 && InsecureRandBool() == 0) {
                 stack.back()->Flush();
                 delete stack.back();
                 stack.pop_back();
             }
             if (stack.size() == 0 || (stack.size() < 4 && InsecureRandBool())) {
                 CCoinsView *tip = &base;
                 if (stack.size() > 0) {
                     tip = stack.back();
                 }
                 stack.push_back(new CCoinsViewCacheTest(tip));
             }
         }
     }
 
     // Clean up the stack.
     while (stack.size() > 0) {
         delete stack.back();
         stack.pop_back();
     }
 
     // Verify coverage.
     BOOST_CHECK(spent_a_duplicate_coinbase);
 }
 
 BOOST_AUTO_TEST_CASE(coin_serialization) {
     // Good example
     CDataStream ss1(
         ParseHex("97f23c835800816115944e077fe7c803cfa57f29b36bf87c1d35"),
         SER_DISK, CLIENT_VERSION);
     Coin c1;
     ss1 >> c1;
     BOOST_CHECK_EQUAL(c1.IsCoinBase(), false);
     BOOST_CHECK_EQUAL(c1.GetHeight(), 203998U);
     BOOST_CHECK_EQUAL(c1.GetTxOut().nValue, int64_t(60000000000) * SATOSHI);
     BOOST_CHECK_EQUAL(HexStr(c1.GetTxOut().scriptPubKey),
                       HexStr(GetScriptForDestination(CKeyID(uint160(ParseHex(
                           "816115944e077fe7c803cfa57f29b36bf87c1d35"))))));
 
     // Good example
     CDataStream ss2(
         ParseHex("8ddf77bbd123008c988f1a4a4de2161e0f50aac7f17e7f9555caa4"),
         SER_DISK, CLIENT_VERSION);
     Coin c2;
     ss2 >> c2;
     BOOST_CHECK_EQUAL(c2.IsCoinBase(), true);
     BOOST_CHECK_EQUAL(c2.GetHeight(), 120891U);
     BOOST_CHECK_EQUAL(c2.GetTxOut().nValue, 110397 * SATOSHI);
     BOOST_CHECK_EQUAL(HexStr(c2.GetTxOut().scriptPubKey),
                       HexStr(GetScriptForDestination(CKeyID(uint160(ParseHex(
                           "8c988f1a4a4de2161e0f50aac7f17e7f9555caa4"))))));
 
     // Smallest possible example
     CDataStream ss3(ParseHex("000006"), SER_DISK, CLIENT_VERSION);
     Coin c3;
     ss3 >> c3;
     BOOST_CHECK_EQUAL(c3.IsCoinBase(), false);
     BOOST_CHECK_EQUAL(c3.GetHeight(), 0U);
     BOOST_CHECK_EQUAL(c3.GetTxOut().nValue, Amount::zero());
     BOOST_CHECK_EQUAL(c3.GetTxOut().scriptPubKey.size(), 0U);
 
     // scriptPubKey that ends beyond the end of the stream
     CDataStream ss4(ParseHex("000007"), SER_DISK, CLIENT_VERSION);
     try {
         Coin c4;
         ss4 >> c4;
         BOOST_CHECK_MESSAGE(false, "We should have thrown");
     } catch (const std::ios_base::failure &e) {
     }
 
     // Very large scriptPubKey (3*10^9 bytes) past the end of the stream
     CDataStream tmp(SER_DISK, CLIENT_VERSION);
     uint64_t x = 3000000000ULL;
     tmp << VARINT(x);
     BOOST_CHECK_EQUAL(HexStr(tmp.begin(), tmp.end()), "8a95c0bb00");
     CDataStream ss5(ParseHex("00008a95c0bb00"), SER_DISK, CLIENT_VERSION);
     try {
         Coin c5;
         ss5 >> c5;
         BOOST_CHECK_MESSAGE(false, "We should have thrown");
     } catch (const std::ios_base::failure &e) {
     }
 }
 
 static const COutPoint OUTPOINT;
 static const Amount PRUNED(-1 * SATOSHI);
 static const Amount ABSENT(-2 * SATOSHI);
 static const Amount FAIL(-3 * SATOSHI);
 static const Amount VALUE1(100 * SATOSHI);
 static const Amount VALUE2(200 * SATOSHI);
 static const Amount VALUE3(300 * SATOSHI);
 static const char DIRTY = CCoinsCacheEntry::DIRTY;
 static const char FRESH = CCoinsCacheEntry::FRESH;
 static const char NO_ENTRY = -1;
 
 static const auto FLAGS = {char(0), FRESH, DIRTY, char(DIRTY | FRESH)};
 static const auto CLEAN_FLAGS = {char(0), FRESH};
 static const auto ABSENT_FLAGS = {NO_ENTRY};
 
 static void SetCoinValue(const Amount value, Coin &coin) {
     assert(value != ABSENT);
     coin.Clear();
     assert(coin.IsSpent());
     if (value != PRUNED) {
         CTxOut out;
         out.nValue = value;
         coin = Coin(std::move(out), 1, false);
         assert(!coin.IsSpent());
     }
 }
 
 static size_t InsertCoinMapEntry(CCoinsMap &map, const Amount value,
                                  char flags) {
     if (value == ABSENT) {
         assert(flags == NO_ENTRY);
         return 0;
     }
     assert(flags != NO_ENTRY);
     CCoinsCacheEntry entry;
     entry.flags = flags;
     SetCoinValue(value, entry.coin);
     auto inserted = map.emplace(OUTPOINT, std::move(entry));
     assert(inserted.second);
     return inserted.first->second.coin.DynamicMemoryUsage();
 }
 
 void GetCoinMapEntry(const CCoinsMap &map, Amount &value, char &flags) {
     auto it = map.find(OUTPOINT);
     if (it == map.end()) {
         value = ABSENT;
         flags = NO_ENTRY;
     } else {
         if (it->second.coin.IsSpent()) {
             value = PRUNED;
         } else {
             value = it->second.coin.GetTxOut().nValue;
         }
         flags = it->second.flags;
         assert(flags != NO_ENTRY);
     }
 }
 
 void WriteCoinViewEntry(CCoinsView &view, const Amount value, char flags) {
     CCoinsMap map;
     InsertCoinMapEntry(map, value, flags);
     view.BatchWrite(map, {});
 }
 
 class SingleEntryCacheTest {
 public:
     SingleEntryCacheTest(const Amount base_value, const Amount cache_value,
                          char cache_flags) {
         WriteCoinViewEntry(base, base_value,
                            base_value == ABSENT ? NO_ENTRY : DIRTY);
         cache.usage() +=
             InsertCoinMapEntry(cache.map(), cache_value, cache_flags);
     }
 
     CCoinsView root;
     CCoinsViewCacheTest base{&root};
     CCoinsViewCacheTest cache{&base};
 };
 
 static void CheckAccessCoin(const Amount base_value, const Amount cache_value,
                             const Amount expected_value, char cache_flags,
                             char expected_flags) {
     SingleEntryCacheTest test(base_value, cache_value, cache_flags);
     test.cache.AccessCoin(OUTPOINT);
     test.cache.SelfTest();
 
     Amount result_value;
     char result_flags;
     GetCoinMapEntry(test.cache.map(), result_value, result_flags);
     BOOST_CHECK_EQUAL(result_value, expected_value);
     BOOST_CHECK_EQUAL(result_flags, expected_flags);
 }
 
 BOOST_AUTO_TEST_CASE(coin_access) {
     /* Check AccessCoin behavior, requesting a coin from a cache view layered on
      * top of a base view, and checking the resulting entry in the cache after
      * the access.
      *
      *               Base    Cache   Result  Cache        Result
      *               Value   Value   Value   Flags        Flags
      */
     CheckAccessCoin(ABSENT, ABSENT, ABSENT, NO_ENTRY, NO_ENTRY);
     CheckAccessCoin(ABSENT, PRUNED, PRUNED, 0, 0);
     CheckAccessCoin(ABSENT, PRUNED, PRUNED, FRESH, FRESH);
     CheckAccessCoin(ABSENT, PRUNED, PRUNED, DIRTY, DIRTY);
     CheckAccessCoin(ABSENT, PRUNED, PRUNED, DIRTY | FRESH, DIRTY | FRESH);
     CheckAccessCoin(ABSENT, VALUE2, VALUE2, 0, 0);
     CheckAccessCoin(ABSENT, VALUE2, VALUE2, FRESH, FRESH);
     CheckAccessCoin(ABSENT, VALUE2, VALUE2, DIRTY, DIRTY);
     CheckAccessCoin(ABSENT, VALUE2, VALUE2, DIRTY | FRESH, DIRTY | FRESH);
     CheckAccessCoin(PRUNED, ABSENT, ABSENT, NO_ENTRY, NO_ENTRY);
     CheckAccessCoin(PRUNED, PRUNED, PRUNED, 0, 0);
     CheckAccessCoin(PRUNED, PRUNED, PRUNED, FRESH, FRESH);
     CheckAccessCoin(PRUNED, PRUNED, PRUNED, DIRTY, DIRTY);
     CheckAccessCoin(PRUNED, PRUNED, PRUNED, DIRTY | FRESH, DIRTY | FRESH);
     CheckAccessCoin(PRUNED, VALUE2, VALUE2, 0, 0);
     CheckAccessCoin(PRUNED, VALUE2, VALUE2, FRESH, FRESH);
     CheckAccessCoin(PRUNED, VALUE2, VALUE2, DIRTY, DIRTY);
     CheckAccessCoin(PRUNED, VALUE2, VALUE2, DIRTY | FRESH, DIRTY | FRESH);
     CheckAccessCoin(VALUE1, ABSENT, VALUE1, NO_ENTRY, 0);
     CheckAccessCoin(VALUE1, PRUNED, PRUNED, 0, 0);
     CheckAccessCoin(VALUE1, PRUNED, PRUNED, FRESH, FRESH);
     CheckAccessCoin(VALUE1, PRUNED, PRUNED, DIRTY, DIRTY);
     CheckAccessCoin(VALUE1, PRUNED, PRUNED, DIRTY | FRESH, DIRTY | FRESH);
     CheckAccessCoin(VALUE1, VALUE2, VALUE2, 0, 0);
     CheckAccessCoin(VALUE1, VALUE2, VALUE2, FRESH, FRESH);
     CheckAccessCoin(VALUE1, VALUE2, VALUE2, DIRTY, DIRTY);
     CheckAccessCoin(VALUE1, VALUE2, VALUE2, DIRTY | FRESH, DIRTY | FRESH);
 }
 
 static void CheckSpendCoin(Amount base_value, Amount cache_value,
                            Amount expected_value, char cache_flags,
                            char expected_flags) {
     SingleEntryCacheTest test(base_value, cache_value, cache_flags);
     test.cache.SpendCoin(OUTPOINT);
     test.cache.SelfTest();
 
     Amount result_value;
     char result_flags;
     GetCoinMapEntry(test.cache.map(), result_value, result_flags);
     BOOST_CHECK_EQUAL(result_value, expected_value);
     BOOST_CHECK_EQUAL(result_flags, expected_flags);
 };
 
 BOOST_AUTO_TEST_CASE(coin_spend) {
     /**
      * Check SpendCoin behavior, requesting a coin from a cache view layered on
      * top of a base view, spending, and then checking the resulting entry in
      * the cache after the modification.
      *
      *              Base    Cache   Result  Cache        Result
      *              Value   Value   Value   Flags        Flags
      */
     CheckSpendCoin(ABSENT, ABSENT, ABSENT, NO_ENTRY, NO_ENTRY);
     CheckSpendCoin(ABSENT, PRUNED, PRUNED, 0, DIRTY);
     CheckSpendCoin(ABSENT, PRUNED, ABSENT, FRESH, NO_ENTRY);
     CheckSpendCoin(ABSENT, PRUNED, PRUNED, DIRTY, DIRTY);
     CheckSpendCoin(ABSENT, PRUNED, ABSENT, DIRTY | FRESH, NO_ENTRY);
     CheckSpendCoin(ABSENT, VALUE2, PRUNED, 0, DIRTY);
     CheckSpendCoin(ABSENT, VALUE2, ABSENT, FRESH, NO_ENTRY);
     CheckSpendCoin(ABSENT, VALUE2, PRUNED, DIRTY, DIRTY);
     CheckSpendCoin(ABSENT, VALUE2, ABSENT, DIRTY | FRESH, NO_ENTRY);
     CheckSpendCoin(PRUNED, ABSENT, ABSENT, NO_ENTRY, NO_ENTRY);
     CheckSpendCoin(PRUNED, PRUNED, PRUNED, 0, DIRTY);
     CheckSpendCoin(PRUNED, PRUNED, ABSENT, FRESH, NO_ENTRY);
     CheckSpendCoin(PRUNED, PRUNED, PRUNED, DIRTY, DIRTY);
     CheckSpendCoin(PRUNED, PRUNED, ABSENT, DIRTY | FRESH, NO_ENTRY);
     CheckSpendCoin(PRUNED, VALUE2, PRUNED, 0, DIRTY);
     CheckSpendCoin(PRUNED, VALUE2, ABSENT, FRESH, NO_ENTRY);
     CheckSpendCoin(PRUNED, VALUE2, PRUNED, DIRTY, DIRTY);
     CheckSpendCoin(PRUNED, VALUE2, ABSENT, DIRTY | FRESH, NO_ENTRY);
     CheckSpendCoin(VALUE1, ABSENT, PRUNED, NO_ENTRY, DIRTY);
     CheckSpendCoin(VALUE1, PRUNED, PRUNED, 0, DIRTY);
     CheckSpendCoin(VALUE1, PRUNED, ABSENT, FRESH, NO_ENTRY);
     CheckSpendCoin(VALUE1, PRUNED, PRUNED, DIRTY, DIRTY);
     CheckSpendCoin(VALUE1, PRUNED, ABSENT, DIRTY | FRESH, NO_ENTRY);
     CheckSpendCoin(VALUE1, VALUE2, PRUNED, 0, DIRTY);
     CheckSpendCoin(VALUE1, VALUE2, ABSENT, FRESH, NO_ENTRY);
     CheckSpendCoin(VALUE1, VALUE2, PRUNED, DIRTY, DIRTY);
     CheckSpendCoin(VALUE1, VALUE2, ABSENT, DIRTY | FRESH, NO_ENTRY);
 }
 
 static void CheckAddCoinBase(Amount base_value, Amount cache_value,
                              Amount modify_value, Amount expected_value,
                              char cache_flags, char expected_flags,
                              bool coinbase) {
     SingleEntryCacheTest test(base_value, cache_value, cache_flags);
 
     Amount result_value;
     char result_flags;
     try {
         CTxOut output;
         output.nValue = modify_value;
         test.cache.AddCoin(OUTPOINT, Coin(std::move(output), 1, coinbase),
                            coinbase);
         test.cache.SelfTest();
         GetCoinMapEntry(test.cache.map(), result_value, result_flags);
     } catch (std::logic_error &e) {
         result_value = FAIL;
         result_flags = NO_ENTRY;
     }
 
     BOOST_CHECK_EQUAL(result_value, expected_value);
     BOOST_CHECK_EQUAL(result_flags, expected_flags);
 }
 
 // Simple wrapper for CheckAddCoinBase function above that loops through
 // different possible base_values, making sure each one gives the same results.
 // This wrapper lets the coin_add test below be shorter and less repetitive,
 // while still verifying that the CoinsViewCache::AddCoin implementation ignores
 // base values.
 template <typename... Args> static void CheckAddCoin(Args &&... args) {
-    for (const Amount base_value : {ABSENT, PRUNED, VALUE1}) {
+    for (const Amount &base_value : {ABSENT, PRUNED, VALUE1}) {
         CheckAddCoinBase(base_value, std::forward<Args>(args)...);
     }
 }
 
 BOOST_AUTO_TEST_CASE(coin_add) {
     /**
      * Check AddCoin behavior, requesting a new coin from a cache view, writing
      * a modification to the coin, and then checking the resulting entry in the
      * cache after the modification. Verify behavior with the with the AddCoin
      * potential_overwrite argument set to false, and to true.
      *
      * Cache   Write   Result  Cache        Result       potential_overwrite
      * Value   Value   Value   Flags        Flags
      */
     CheckAddCoin(ABSENT, VALUE3, VALUE3, NO_ENTRY, DIRTY | FRESH, false);
     CheckAddCoin(ABSENT, VALUE3, VALUE3, NO_ENTRY, DIRTY, true);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, 0, DIRTY | FRESH, false);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, 0, DIRTY, true);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, FRESH, DIRTY | FRESH, false);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, FRESH, DIRTY | FRESH, true);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, DIRTY, DIRTY, false);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, DIRTY, DIRTY, true);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, DIRTY | FRESH, DIRTY | FRESH, false);
     CheckAddCoin(PRUNED, VALUE3, VALUE3, DIRTY | FRESH, DIRTY | FRESH, true);
     CheckAddCoin(VALUE2, VALUE3, FAIL, 0, NO_ENTRY, false);
     CheckAddCoin(VALUE2, VALUE3, VALUE3, 0, DIRTY, true);
     CheckAddCoin(VALUE2, VALUE3, FAIL, FRESH, NO_ENTRY, false);
     CheckAddCoin(VALUE2, VALUE3, VALUE3, FRESH, DIRTY | FRESH, true);
     CheckAddCoin(VALUE2, VALUE3, FAIL, DIRTY, NO_ENTRY, false);
     CheckAddCoin(VALUE2, VALUE3, VALUE3, DIRTY, DIRTY, true);
     CheckAddCoin(VALUE2, VALUE3, FAIL, DIRTY | FRESH, NO_ENTRY, false);
     CheckAddCoin(VALUE2, VALUE3, VALUE3, DIRTY | FRESH, DIRTY | FRESH, true);
 }
 
 void CheckWriteCoin(Amount parent_value, Amount child_value,
                     Amount expected_value, char parent_flags, char child_flags,
                     char expected_flags) {
     SingleEntryCacheTest test(ABSENT, parent_value, parent_flags);
 
     Amount result_value;
     char result_flags;
     try {
         WriteCoinViewEntry(test.cache, child_value, child_flags);
         test.cache.SelfTest();
         GetCoinMapEntry(test.cache.map(), result_value, result_flags);
     } catch (std::logic_error &e) {
         result_value = FAIL;
         result_flags = NO_ENTRY;
     }
 
     BOOST_CHECK_EQUAL(result_value, expected_value);
     BOOST_CHECK_EQUAL(result_flags, expected_flags);
 }
 
 BOOST_AUTO_TEST_CASE(coin_write) {
     /* Check BatchWrite behavior, flushing one entry from a child cache to a
      * parent cache, and checking the resulting entry in the parent cache
      * after the write.
      *
      *              Parent  Child   Result  Parent       Child        Result
      *              Value   Value   Value   Flags        Flags        Flags
      */
     CheckWriteCoin(ABSENT, ABSENT, ABSENT, NO_ENTRY, NO_ENTRY, NO_ENTRY);
     CheckWriteCoin(ABSENT, PRUNED, PRUNED, NO_ENTRY, DIRTY, DIRTY);
     CheckWriteCoin(ABSENT, PRUNED, ABSENT, NO_ENTRY, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(ABSENT, VALUE2, VALUE2, NO_ENTRY, DIRTY, DIRTY);
     CheckWriteCoin(ABSENT, VALUE2, VALUE2, NO_ENTRY, DIRTY | FRESH,
                    DIRTY | FRESH);
     CheckWriteCoin(PRUNED, ABSENT, PRUNED, 0, NO_ENTRY, 0);
     CheckWriteCoin(PRUNED, ABSENT, PRUNED, FRESH, NO_ENTRY, FRESH);
     CheckWriteCoin(PRUNED, ABSENT, PRUNED, DIRTY, NO_ENTRY, DIRTY);
     CheckWriteCoin(PRUNED, ABSENT, PRUNED, DIRTY | FRESH, NO_ENTRY,
                    DIRTY | FRESH);
     CheckWriteCoin(PRUNED, PRUNED, PRUNED, 0, DIRTY, DIRTY);
     CheckWriteCoin(PRUNED, PRUNED, PRUNED, 0, DIRTY | FRESH, DIRTY);
     CheckWriteCoin(PRUNED, PRUNED, ABSENT, FRESH, DIRTY, NO_ENTRY);
     CheckWriteCoin(PRUNED, PRUNED, ABSENT, FRESH, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(PRUNED, PRUNED, PRUNED, DIRTY, DIRTY, DIRTY);
     CheckWriteCoin(PRUNED, PRUNED, PRUNED, DIRTY, DIRTY | FRESH, DIRTY);
     CheckWriteCoin(PRUNED, PRUNED, ABSENT, DIRTY | FRESH, DIRTY, NO_ENTRY);
     CheckWriteCoin(PRUNED, PRUNED, ABSENT, DIRTY | FRESH, DIRTY | FRESH,
                    NO_ENTRY);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, 0, DIRTY, DIRTY);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, 0, DIRTY | FRESH, DIRTY);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, FRESH, DIRTY, DIRTY | FRESH);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, FRESH, DIRTY | FRESH, DIRTY | FRESH);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, DIRTY, DIRTY, DIRTY);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, DIRTY, DIRTY | FRESH, DIRTY);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, DIRTY | FRESH, DIRTY, DIRTY | FRESH);
     CheckWriteCoin(PRUNED, VALUE2, VALUE2, DIRTY | FRESH, DIRTY | FRESH,
                    DIRTY | FRESH);
     CheckWriteCoin(VALUE1, ABSENT, VALUE1, 0, NO_ENTRY, 0);
     CheckWriteCoin(VALUE1, ABSENT, VALUE1, FRESH, NO_ENTRY, FRESH);
     CheckWriteCoin(VALUE1, ABSENT, VALUE1, DIRTY, NO_ENTRY, DIRTY);
     CheckWriteCoin(VALUE1, ABSENT, VALUE1, DIRTY | FRESH, NO_ENTRY,
                    DIRTY | FRESH);
     CheckWriteCoin(VALUE1, PRUNED, PRUNED, 0, DIRTY, DIRTY);
     CheckWriteCoin(VALUE1, PRUNED, FAIL, 0, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(VALUE1, PRUNED, ABSENT, FRESH, DIRTY, NO_ENTRY);
     CheckWriteCoin(VALUE1, PRUNED, FAIL, FRESH, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(VALUE1, PRUNED, PRUNED, DIRTY, DIRTY, DIRTY);
     CheckWriteCoin(VALUE1, PRUNED, FAIL, DIRTY, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(VALUE1, PRUNED, ABSENT, DIRTY | FRESH, DIRTY, NO_ENTRY);
     CheckWriteCoin(VALUE1, PRUNED, FAIL, DIRTY | FRESH, DIRTY | FRESH,
                    NO_ENTRY);
     CheckWriteCoin(VALUE1, VALUE2, VALUE2, 0, DIRTY, DIRTY);
     CheckWriteCoin(VALUE1, VALUE2, FAIL, 0, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(VALUE1, VALUE2, VALUE2, FRESH, DIRTY, DIRTY | FRESH);
     CheckWriteCoin(VALUE1, VALUE2, FAIL, FRESH, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(VALUE1, VALUE2, VALUE2, DIRTY, DIRTY, DIRTY);
     CheckWriteCoin(VALUE1, VALUE2, FAIL, DIRTY, DIRTY | FRESH, NO_ENTRY);
     CheckWriteCoin(VALUE1, VALUE2, VALUE2, DIRTY | FRESH, DIRTY, DIRTY | FRESH);
     CheckWriteCoin(VALUE1, VALUE2, FAIL, DIRTY | FRESH, DIRTY | FRESH,
                    NO_ENTRY);
 
     // The checks above omit cases where the child flags are not DIRTY, since
     // they would be too repetitive (the parent cache is never updated in these
     // cases). The loop below covers these cases and makes sure the parent cache
     // is always left unchanged.
-    for (const Amount parent_value : {ABSENT, PRUNED, VALUE1}) {
-        for (const Amount child_value : {ABSENT, PRUNED, VALUE2}) {
+    for (const Amount &parent_value : {ABSENT, PRUNED, VALUE1}) {
+        for (const Amount &child_value : {ABSENT, PRUNED, VALUE2}) {
             for (const char parent_flags :
                  parent_value == ABSENT ? ABSENT_FLAGS : FLAGS) {
                 for (const char child_flags :
                      child_value == ABSENT ? ABSENT_FLAGS : CLEAN_FLAGS) {
                     CheckWriteCoin(parent_value, child_value, parent_value,
                                    parent_flags, child_flags, parent_flags);
                 }
             }
         }
     }
 }
 
 BOOST_AUTO_TEST_SUITE_END()