text: // Copyright (c) 2012-2015 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 "wallet/wallet.h"
  
  #include <set>
  #include <stdint.h>
  #include <utility>
  #include <vector>
  
  #include "test/test_digitalcoin.h"
  
  #include <boost/foreach.hpp>
  #include <boost/test/unit_test.hpp>
  
  // how many times to run all the tests to have a chance to catch errors that only show up with particular random shuffles
  #define RUN_TESTS 100
  
  // some tests fail 1% of the time due to bad luck.
  // we repeat those tests this many times and only complain if all iterations of the test fail
  #define RANDOM_REPEATS 5
  
  using namespace std;
  
  typedef set<pair<const CWalletTx*,unsigned int> > CoinSet;
  
  BOOST_FIXTURE_TEST_SUITE(wallet_tests, TestingSetup)
  
  static CWallet wallet;
  static vector<COutput> vCoins;
  
  static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = false, int nInput=0)
  {
      static int nextLockTime = 0;
      CMutableTransaction tx;
      tx.nLockTime = nextLockTime++;        // so all transactions get different hashes
      tx.vout.resize(nInput+1);
      tx.vout[nInput].nValue = nValue;
      if (fIsFromMe) {
          // IsFromMe() returns (GetDebit() > 0), and GetDebit() is 0 if vin.empty(),
          // so stop vin being empty, and cache a non-zero Debit to fake out IsFromMe()
          tx.vin.resize(1);
      }
      CWalletTx* wtx = new CWalletTx(&wallet, tx);
      if (fIsFromMe)
      {
          wtx->fDebitCached = true;
          wtx->nDebitCached = 1;
      }
      COutput output(wtx, nInput, nAge, true, true);
      vCoins.push_back(output);
  }
  
  static void empty_wallet(void)
  {
      BOOST_FOREACH(COutput output, vCoins)
          delete output.tx;
      vCoins.clear();
  }
  
  static bool equal_sets(CoinSet a, CoinSet b)
  {
      pair<CoinSet::iterator, CoinSet::iterator> ret = mismatch(a.begin(), a.end(), b.begin());
      return ret.first == a.end() && ret.second == b.end();
  }
  
  BOOST_AUTO_TEST_CASE(coin_selection_tests)
  {
      CoinSet setCoinsRet, setCoinsRet2;
      CAmount nValueRet;
  
      LOCK(wallet.cs_wallet);
  
      // test multiple times to allow for differences in the shuffle order
      for (int i = 0; i < RUN_TESTS; i++)
      {
          empty_wallet();
  
          // with an empty wallet we can't even pay one cent
          BOOST_CHECK(!wallet.SelectCoinsMinConf( 1 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
  
          add_coin(1*CENT, 4);        // add a new 1 cent coin
  
          // with a new 1 cent coin, we still can't find a mature 1 cent
          BOOST_CHECK(!wallet.SelectCoinsMinConf( 1 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
  
          // but we can find a new 1 cent
          BOOST_CHECK( wallet.SelectCoinsMinConf( 1 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 1 * CENT);
  
          add_coin(2*CENT);           // add a mature 2 cent coin
  
          // we can't make 3 cents of mature coins
          BOOST_CHECK(!wallet.SelectCoinsMinConf( 3 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
  
          // we can make 3 cents of new  coins
          BOOST_CHECK( wallet.SelectCoinsMinConf( 3 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 3 * CENT);
  
          add_coin(5*CENT);           // add a mature 5 cent coin,
          add_coin(10*CENT, 3, true); // a new 10 cent coin sent from one of our own addresses
          add_coin(20*CENT);          // and a mature 20 cent coin
  
          // now we have new: 1+10=11 (of which 10 was self-sent), and mature: 2+5+20=27.  total = 38
  
          // we can't make 38 cents only if we disallow new coins:
          BOOST_CHECK(!wallet.SelectCoinsMinConf(38 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
          // we can't even make 37 cents if we don't allow new coins even if they're from us
          BOOST_CHECK(!wallet.SelectCoinsMinConf(38 * CENT, 6, 6, vCoins, setCoinsRet, nValueRet));
          // but we can make 37 cents if we accept new coins from ourself
          BOOST_CHECK( wallet.SelectCoinsMinConf(37 * CENT, 1, 6, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 37 * CENT);
          // and we can make 38 cents if we accept all new coins
          BOOST_CHECK( wallet.SelectCoinsMinConf(38 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 38 * CENT);
  
          // try making 34 cents from 1,2,5,10,20 - we can't do it exactly
          BOOST_CHECK( wallet.SelectCoinsMinConf(34 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 35 * CENT);       // but 35 cents is closest
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);     // the best should be 20+10+5.  it's incredibly unlikely the 1 or 2 got included (but possible)
  
          // when we try making 7 cents, the smaller coins (1,2,5) are enough.  We should see just 2+5
          BOOST_CHECK( wallet.SelectCoinsMinConf( 7 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 7 * CENT);
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
  
          // when we try making 8 cents, the smaller coins (1,2,5) are exactly enough.
          BOOST_CHECK( wallet.SelectCoinsMinConf( 8 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK(nValueRet == 8 * CENT);
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
  
          // when we try making 9 cents, no subset of smaller coins is enough, and we get the next bigger coin (10)
          BOOST_CHECK( wallet.SelectCoinsMinConf( 9 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 10 * CENT);
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
  
          // now clear out the wallet and start again to test choosing between subsets of smaller coins and the next biggest coin
          empty_wallet();
  
          add_coin( 6*CENT);
          add_coin( 7*CENT);
          add_coin( 8*CENT);
          add_coin(20*CENT);
          add_coin(30*CENT); // now we have 6+7+8+20+30 = 71 cents total
  
          // check that we have 71 and not 72
          BOOST_CHECK( wallet.SelectCoinsMinConf(71 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK(!wallet.SelectCoinsMinConf(72 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
  
          // now try making 16 cents.  the best smaller coins can do is 6+7+8 = 21; not as good at the next biggest coin, 20
          BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 20 * CENT); // we should get 20 in one coin
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
  
          add_coin( 5*CENT); // now we have 5+6+7+8+20+30 = 75 cents total
  
          // now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, better than the next biggest coin, 20
          BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 18 * CENT); // we should get 18 in 3 coins
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
  
          add_coin( 18*CENT); // now we have 5+6+7+8+18+20+30
  
          // and now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, the same as the next biggest coin, 18
          BOOST_CHECK( wallet.SelectCoinsMinConf(16 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 18 * CENT);  // we should get 18 in 1 coin
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U); // because in the event of a tie, the biggest coin wins
  
          // now try making 11 cents.  we should get 5+6
          BOOST_CHECK( wallet.SelectCoinsMinConf(11 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 11 * CENT);
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
  
          // check that the smallest bigger coin is used
          add_coin( 1*COIN);
          add_coin( 2*COIN);
          add_coin( 3*COIN);
          add_coin( 4*COIN); // now we have 5+6+7+8+18+20+30+100+200+300+400 = 1094 cents
          BOOST_CHECK( wallet.SelectCoinsMinConf(95 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 1 * COIN);  // we should get 1 BTC in 1 coin
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
  
          BOOST_CHECK( wallet.SelectCoinsMinConf(195 * CENT, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 2 * COIN);  // we should get 2 BTC in 1 coin
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
  
          // empty the wallet and start again, now with fractions of a cent, to test small change avoidance
  
          empty_wallet();
          add_coin(0.1*MIN_CHANGE);
          add_coin(0.2*MIN_CHANGE);
          add_coin(0.3*MIN_CHANGE);
          add_coin(0.4*MIN_CHANGE);
          add_coin(0.5*MIN_CHANGE);
  
          // try making 1 * MIN_CHANGE from the 1.5 * MIN_CHANGE
          // we'll get change smaller than MIN_CHANGE whatever happens, so can expect MIN_CHANGE exactly
          BOOST_CHECK( wallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);
  
          // but if we add a bigger coin, small change is avoided
          add_coin(1111*MIN_CHANGE);
  
          // try making 1 from 0.1 + 0.2 + 0.3 + 0.4 + 0.5 + 1111 = 1112.5
          BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
  
          // if we add more small coins:
          add_coin(0.6*MIN_CHANGE);
          add_coin(0.7*MIN_CHANGE);
  
          // and try again to make 1.0 * MIN_CHANGE
          BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
  
          // run the 'mtgox' test (see http://blockexplorer.com/tx/29a3efd3ef04f9153d47a990bd7b048a4b2d213daaa5fb8ed670fb85f13bdbcf)
          // they tried to consolidate 10 50k coins into one 500k coin, and ended up with 50k in change
          empty_wallet();
          for (int i = 0; i < 20; i++)
              add_coin(50000 * COIN);
  
          BOOST_CHECK( wallet.SelectCoinsMinConf(500000 * COIN, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 500000 * COIN); // we should get the exact amount
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 10U); // in ten coins
  
          // if there's not enough in the smaller coins to make at least 1 * MIN_CHANGE change (0.5+0.6+0.7 < 1.0+1.0),
          // we need to try finding an exact subset anyway
  
          // sometimes it will fail, and so we use the next biggest coin:
          empty_wallet();
          add_coin(0.5 * MIN_CHANGE);
          add_coin(0.6 * MIN_CHANGE);
          add_coin(0.7 * MIN_CHANGE);
          add_coin(1111 * MIN_CHANGE);
          BOOST_CHECK( wallet.SelectCoinsMinConf(1 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 1111 * MIN_CHANGE); // we get the bigger coin
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
  
          // but sometimes it's possible, and we use an exact subset (0.4 + 0.6 = 1.0)
          empty_wallet();
          add_coin(0.4 * MIN_CHANGE);
          add_coin(0.6 * MIN_CHANGE);
          add_coin(0.8 * MIN_CHANGE);
          add_coin(1111 * MIN_CHANGE);
          BOOST_CHECK( wallet.SelectCoinsMinConf(MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);   // we should get the exact amount
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U); // in two coins 0.4+0.6
  
          // test avoiding small change
          empty_wallet();
          add_coin(0.05 * MIN_CHANGE);
          add_coin(1    * MIN_CHANGE);
          add_coin(100  * MIN_CHANGE);
  
          // trying to make 100.01 from these three coins
          BOOST_CHECK( wallet.SelectCoinsMinConf(100.01 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 101.05 * MIN_CHANGE);   // we should get all coins
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
  
          // but if we try to make 99.9, we should take the bigger of the two small coins to avoid small change
          BOOST_CHECK( wallet.SelectCoinsMinConf(99.9 * MIN_CHANGE, 1, 1, vCoins, setCoinsRet, nValueRet));
          BOOST_CHECK_EQUAL(nValueRet, 101 * MIN_CHANGE);
          BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
  
          // test with many inputs
          for (CAmount amt=1500; amt < COIN; amt*=10) {
               empty_wallet();
               // Create 676 inputs (= MAX_STANDARD_TX_SIZE / 148 bytes per input)
               for (uint16_t j = 0; j < 676; j++)
                   add_coin(amt);
               BOOST_CHECK(wallet.SelectCoinsMinConf(2000, 1, 1, vCoins, setCoinsRet, nValueRet));
               if (amt - 2000 < MIN_CHANGE) {
                   // needs more than one input:
                   uint16_t returnSize = std::ceil((2000.0 + MIN_CHANGE)/amt);
                   CAmount returnValue = amt * returnSize;
                   BOOST_CHECK_EQUAL(nValueRet, returnValue);
                   BOOST_CHECK_EQUAL(setCoinsRet.size(), returnSize);
               } else {
                   // one input is sufficient:
                   BOOST_CHECK_EQUAL(nValueRet, amt);
                   BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
               }
          }
  
          // test randomness
          {
              empty_wallet();
              for (int i2 = 0; i2 < 100; i2++)
                  add_coin(COIN);
  
              // picking 50 from 100 coins doesn't depend on the shuffle,
              // but does depend on randomness in the stochastic approximation code
              BOOST_CHECK(wallet.SelectCoinsMinConf(50 * COIN, 1, 6, vCoins, setCoinsRet , nValueRet));
              BOOST_CHECK(wallet.SelectCoinsMinConf(50 * COIN, 1, 6, vCoins, setCoinsRet2, nValueRet));
              BOOST_CHECK(!equal_sets(setCoinsRet, setCoinsRet2));
  
              int fails = 0;
              for (int i = 0; i < RANDOM_REPEATS; i++)
              {
                  // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
                  // run the test RANDOM_REPEATS times and only complain if all of them fail
                  BOOST_CHECK(wallet.SelectCoinsMinConf(COIN, 1, 6, vCoins, setCoinsRet , nValueRet));
                  BOOST_CHECK(wallet.SelectCoinsMinConf(COIN, 1, 6, vCoins, setCoinsRet2, nValueRet));
                  if (equal_sets(setCoinsRet, setCoinsRet2))
                      fails++;
              }
              BOOST_CHECK_NE(fails, RANDOM_REPEATS);
  
              // add 75 cents in small change.  not enough to make 90 cents,
              // then try making 90 cents.  there are multiple competing "smallest bigger" coins,
              // one of which should be picked at random
              add_coin( 5*CENT); add_coin(10*CENT); add_coin(15*CENT); add_coin(20*CENT); add_coin(25*CENT);
  
              fails = 0;
              for (int i = 0; i < RANDOM_REPEATS; i++)
              {
                  // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
                  // run the test RANDOM_REPEATS times and only complain if all of them fail
                  BOOST_CHECK(wallet.SelectCoinsMinConf(90*CENT, 1, 6, vCoins, setCoinsRet , nValueRet));
                  BOOST_CHECK(wallet.SelectCoinsMinConf(90*CENT, 1, 6, vCoins, setCoinsRet2, nValueRet));
                  if (equal_sets(setCoinsRet, setCoinsRet2))
                      fails++;
              }
              BOOST_CHECK_NE(fails, RANDOM_REPEATS);
          }
      }
      empty_wallet();
  }
  
  BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
  {
      CoinSet setCoinsRet;
      CAmount nValueRet;
  
      LOCK(wallet.cs_wallet);
  
      empty_wallet();
  
      // Test vValue sort order
      for (int i = 0; i < 1000; i++)
          add_coin(1000 * COIN);
      add_coin(3 * COIN);
  
      BOOST_CHECK(wallet.SelectCoinsMinConf(1003 * COIN, 1, 6, vCoins, setCoinsRet, nValueRet));
      BOOST_CHECK_EQUAL(nValueRet, 1003 * COIN);
      BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
  
      empty_wallet();
  
      // Test trimming
      for (int i = 0; i < 100; i++)
          add_coin(10 * COIN);
      for (int i = 0; i < 100; i++)
          add_coin(1000 * COIN);
  
      BOOST_CHECK(wallet.SelectCoinsMinConf(100001 * COIN, 1, 6, vCoins, setCoinsRet, nValueRet));
      // We need all 100 larger coins and exactly one small coin.
      // Superfluous small coins must be trimmed from the set:
      BOOST_CHECK_EQUAL(nValueRet, 100010 * COIN);
      BOOST_CHECK_EQUAL(setCoinsRet.size(), 101);
  }
  
  BOOST_AUTO_TEST_SUITE_END()
  