2018-04-01 07:32:10 -07:00
|
|
|
#include <gtest/gtest.h>
|
|
|
|
|
2018-04-03 20:14:22 -07:00
|
|
|
#include <chain.h>
|
|
|
|
#include <chainparams.h>
|
|
|
|
#include <pow.h>
|
|
|
|
#include <random.h>
|
2018-04-01 07:32:10 -07:00
|
|
|
|
|
|
|
TEST(PoW, DifficultyAveraging) {
|
|
|
|
SelectParams(CBaseChainParams::MAIN);
|
|
|
|
const Consensus::Params& params = Params().GetConsensus();
|
|
|
|
size_t lastBlk = 2*params.nPowAveragingWindow;
|
|
|
|
size_t firstBlk = lastBlk - params.nPowAveragingWindow;
|
|
|
|
|
|
|
|
// Start with blocks evenly-spaced and equal difficulty
|
|
|
|
std::vector<CBlockIndex> blocks(lastBlk+1);
|
|
|
|
for (int i = 0; i <= lastBlk; i++) {
|
|
|
|
blocks[i].pprev = i ? &blocks[i - 1] : nullptr;
|
|
|
|
blocks[i].nHeight = i;
|
|
|
|
blocks[i].nTime = 1269211443 + i * params.nPowTargetSpacing;
|
|
|
|
blocks[i].nBits = 0x1e7fffff; /* target 0x007fffff000... */
|
|
|
|
blocks[i].nChainWork = i ? blocks[i - 1].nChainWork + GetBlockProof(blocks[i - 1]) : arith_uint256(0);
|
|
|
|
}
|
|
|
|
|
|
|
|
// Result should be the same as if last difficulty was used
|
|
|
|
arith_uint256 bnAvg;
|
|
|
|
bnAvg.SetCompact(blocks[lastBlk].nBits);
|
|
|
|
EXPECT_EQ(CalculateNextWorkRequired(bnAvg,
|
|
|
|
blocks[lastBlk].GetMedianTimePast(),
|
|
|
|
blocks[firstBlk].GetMedianTimePast(),
|
|
|
|
params),
|
|
|
|
GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
|
|
|
|
// Result should be unchanged, modulo integer division precision loss
|
|
|
|
arith_uint256 bnRes;
|
|
|
|
bnRes.SetCompact(0x1e7fffff);
|
|
|
|
bnRes /= params.AveragingWindowTimespan();
|
|
|
|
bnRes *= params.AveragingWindowTimespan();
|
|
|
|
EXPECT_EQ(bnRes.GetCompact(), GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
|
|
|
|
|
|
|
|
// Randomise the final block time (plus 1 to ensure it is always different)
|
|
|
|
blocks[lastBlk].nTime += GetRand(params.nPowTargetSpacing/2) + 1;
|
|
|
|
|
|
|
|
// Result should be the same as if last difficulty was used
|
|
|
|
bnAvg.SetCompact(blocks[lastBlk].nBits);
|
|
|
|
EXPECT_EQ(CalculateNextWorkRequired(bnAvg,
|
|
|
|
blocks[lastBlk].GetMedianTimePast(),
|
|
|
|
blocks[firstBlk].GetMedianTimePast(),
|
|
|
|
params),
|
|
|
|
GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
|
|
|
|
// Result should not be unchanged
|
|
|
|
EXPECT_NE(0x1e7fffff, GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
|
|
|
|
|
|
|
|
// Change the final block difficulty
|
|
|
|
blocks[lastBlk].nBits = 0x1e0fffff;
|
|
|
|
|
|
|
|
// Result should not be the same as if last difficulty was used
|
|
|
|
bnAvg.SetCompact(blocks[lastBlk].nBits);
|
|
|
|
EXPECT_NE(CalculateNextWorkRequired(bnAvg,
|
|
|
|
blocks[lastBlk].GetMedianTimePast(),
|
|
|
|
blocks[firstBlk].GetMedianTimePast(),
|
|
|
|
params),
|
|
|
|
GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
|
|
|
|
|
|
|
|
// Result should be the same as if the average difficulty was used
|
|
|
|
arith_uint256 average = UintToArith256(uint256S("0000796968696969696969696969696969696969696969696969696969696969"));
|
|
|
|
EXPECT_EQ(CalculateNextWorkRequired(average,
|
|
|
|
blocks[lastBlk].GetMedianTimePast(),
|
|
|
|
blocks[firstBlk].GetMedianTimePast(),
|
|
|
|
params),
|
|
|
|
GetNextWorkRequired(&blocks[lastBlk], nullptr, params));
|
|
|
|
}
|