public void PresentDifferentChains_AlternativeChainWithMoreChainWorkShouldAlwaysBeMarkedForDownload()
{
// Chain header tree setup.
var ctx = new TestContext();
ChainedHeaderTree cht = ctx.CreateChainedHeaderTree();
ChainedHeader initialChainTip = ctx.ExtendAChain(5);
cht.Initialize(initialChainTip, true);
ctx.ConsensusSettings.UseCheckpoints = false;
// Chains A and B setup.
const int commonChainSize = 4;
const int chainAExtension = 4;
const int chainBExtension = 2;
ChainedHeader commonChainTip = ctx.ExtendAChain(commonChainSize, initialChainTip); // ie. h1=h2=h3=h4
ChainedHeader chainATip = ctx.ExtendAChain(chainAExtension, commonChainTip); // ie. (h1=h2=h3=h4)=a5=a6=a7=a8
ChainedHeader chainBTip = ctx.ExtendAChain(chainBExtension, commonChainTip); // ie. (h1=h2=h3=h4)=b5=b6
List <BlockHeader> listOfChainABlockHeaders = ctx.ChainedHeaderToList(chainATip, commonChainSize + chainAExtension);
List <BlockHeader> listOfChainBBlockHeaders = ctx.ChainedHeaderToList(chainBTip, commonChainSize + chainBExtension);
// Chain A is presented by peer 1. DownloadTo should be chain A tip.
ConnectNewHeadersResult connectNewHeadersResult = cht.ConnectNewHeaders(1, listOfChainABlockHeaders);
ChainedHeader chainedHeaderTo = connectNewHeadersResult.DownloadTo;
chainedHeaderTo.HashBlock.Should().Be(chainATip.HashBlock);
// Set chain A tip as a consensus tip.
cht.ConsensusTipChanged(chainATip);
// Chain B is presented by peer 2. DownloadTo should be not set, as chain
// B has less chain work.
connectNewHeadersResult = cht.ConnectNewHeaders(2, listOfChainBBlockHeaders);
connectNewHeadersResult.DownloadTo.Should().BeNull();
// Add more chain work and blocks into chain B.
const int chainBAdditionalBlocks = 4;
chainBTip = ctx.ExtendAChain(chainBAdditionalBlocks, chainBTip); // ie. (h1=h2=h3=h4)=b5=b6=b7=b8=b9=b10
listOfChainBBlockHeaders = ctx.ChainedHeaderToList(chainBTip, commonChainSize + chainBExtension + chainBAdditionalBlocks);
List <BlockHeader> listOfNewChainBBlockHeaders = listOfChainBBlockHeaders.TakeLast(chainBAdditionalBlocks).ToList();
// Chain B is presented by peer 2 again.
// DownloadTo should now be chain B as B has more chain work than chain A.
// DownloadFrom should be the block where split occurred.
// h1=h2=h3=h4=(b5)=b6=b7=b8=b9=(b10) - from b5 to b10.
connectNewHeadersResult = cht.ConnectNewHeaders(2, listOfNewChainBBlockHeaders);
ChainedHeader chainedHeaderFrom = connectNewHeadersResult.DownloadFrom;
BlockHeader expectedHeaderFrom = listOfChainBBlockHeaders[commonChainSize];
chainedHeaderFrom.Header.GetHash().Should().Be(expectedHeaderFrom.GetHash());
chainedHeaderTo = connectNewHeadersResult.DownloadTo;
chainedHeaderTo.HashBlock.Should().Be(chainBTip.HashBlock);
}
internal void SwitchToChain(ChainedHeaderTree cht, ChainedHeader chainTip, ChainedHeader consumedHeader, int extensionSize)
{
ChainedHeader[] consumedHeaders = consumedHeader.ToArray(extensionSize);
for (int i = 0; i < extensionSize; i++)
{
ChainedHeader currentConsumedCh = consumedHeaders[i];
cht.BlockDataDownloaded(currentConsumedCh, chainTip.GetAncestor(currentConsumedCh.Height).Block);
cht.PartialValidationSucceeded(currentConsumedCh, out bool fullValidationRequired);
cht.ConsensusTipChanged(currentConsumedCh);
}
}
