path: root/core/blockchain_test.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
    "fmt"
    "math/big"
    "math/rand"
    "sync"
    "testing"
    "time"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/consensus"
    "github.com/dexon-foundation/dexon/consensus/ethash"
    "github.com/dexon-foundation/dexon/core/rawdb"
    "github.com/dexon-foundation/dexon/core/state"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/core/vm"
    "github.com/dexon-foundation/dexon/crypto"
    "github.com/dexon-foundation/dexon/ethdb"
    "github.com/dexon-foundation/dexon/params"
)

// So we can deterministically seed different blockchains
var (
    canonicalSeed = 1
    forkSeed      = 2
)

// newCanonical creates a chain database, and injects a deterministic canonical
// chain. Depending on the full flag, if creates either a full block chain or a
// header only chain.
func newCanonical(engine consensus.Engine, n int, full bool) (ethdb.Database, *BlockChain, error) {
    var (
        db = ethdb.NewMemDatabase()
        g  = new(Genesis)
    )

    g.Config = params.TestnetChainConfig
    genesis := g.MustCommit(db)

    // Initialize a fresh chain with only a genesis block
    blockchain, _ := NewBlockChain(db, nil, params.AllEthashProtocolChanges, engine, vm.Config{}, nil)
    // Create and inject the requested chain
    if n == 0 {
        return db, blockchain, nil
    }
    if full {
        // Full block-chain requested
        blocks := makeBlockChain(genesis, n, engine, db, canonicalSeed)
        _, err := blockchain.InsertChain(blocks)
        return db, blockchain, err
    }
    // Header-only chain requested
    headers := makeHeaderChain(genesis.Header(), n, engine, db, canonicalSeed)
    _, err := blockchain.InsertHeaderChain(headers, 1)
    return db, blockchain, err
}

// Test fork of length N starting from block i
func testFork(t *testing.T, blockchain *BlockChain, i, n int, full bool, comparator func(td1, td2 *big.Int)) {
    // Copy old chain up to #i into a new db
    db, blockchain2, err := newCanonical(ethash.NewFaker(), i, full)
    if err != nil {
        t.Fatal("could not make new canonical in testFork", err)
    }
    defer blockchain2.Stop()

    // Assert the chains have the same header/block at #i
    var hash1, hash2 common.Hash
    if full {
        hash1 = blockchain.GetBlockByNumber(uint64(i)).Hash()
        hash2 = blockchain2.GetBlockByNumber(uint64(i)).Hash()
    } else {
        hash1 = blockchain.GetHeaderByNumber(uint64(i)).Hash()
        hash2 = blockchain2.GetHeaderByNumber(uint64(i)).Hash()
    }
    if hash1 != hash2 {
        t.Errorf("chain content mismatch at %d: have hash %v, want hash %v", i, hash2, hash1)
    }
    // Extend the newly created chain
    var (
        blockChainB  []*types.Block
        headerChainB []*types.Header
    )
    if full {
        blockChainB = makeBlockChain(blockchain2.CurrentBlock(), n, ethash.NewFaker(), db, forkSeed)
        if _, err := blockchain2.InsertChain(blockChainB); err != nil {
            t.Fatalf("failed to insert forking chain: %v", err)
        }
    } else {
        headerChainB = makeHeaderChain(blockchain2.CurrentHeader(), n, ethash.NewFaker(), db, forkSeed)
        if _, err := blockchain2.InsertHeaderChain(headerChainB, 1); err != nil {
            t.Fatalf("failed to insert forking chain: %v", err)
        }
    }
    // Sanity check that the forked chain can be imported into the original
    var tdPre, tdPost *big.Int

    if full {
        tdPre = blockchain.GetTdByHash(blockchain.CurrentBlock().Hash())
        if err := testBlockChainImport(blockChainB, blockchain); err != nil {
            t.Fatalf("failed to import forked block chain: %v", err)
        }
        tdPost = blockchain.GetTdByHash(blockChainB[len(blockChainB)-1].Hash())
    } else {
        tdPre = blockchain.GetTdByHash(blockchain.CurrentHeader().Hash())
        if err := testHeaderChainImport(headerChainB, blockchain); err != nil {
            t.Fatalf("failed to import forked header chain: %v", err)
        }
        tdPost = blockchain.GetTdByHash(headerChainB[len(headerChainB)-1].Hash())
    }
    // Compare the total difficulties of the chains
    comparator(tdPre, tdPost)
}

func printChain(bc *BlockChain) {
    for i := bc.CurrentBlock().Number().Uint64(); i > 0; i-- {
        b := bc.GetBlockByNumber(uint64(i))
        fmt.Printf("\t%x %v\n", b.Hash(), b.Difficulty())
    }
}

// testBlockChainImport tries to process a chain of blocks, writing them into
// the database if successful.
func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
    for _, block := range chain {
        // Try and process the block
        err := blockchain.engine.VerifyHeader(blockchain, block.Header(), true)
        if err == nil {
            err = blockchain.validator.ValidateBody(block)
        }
        if err != nil {
            if err == ErrKnownBlock {
                continue
            }
            return err
        }
        statedb, err := state.New(blockchain.GetBlockByHash(block.ParentHash()).Root(), blockchain.stateCache)
        if err != nil {
            return err
        }
        receipts, _, usedGas, err := blockchain.Processor().Process(block, statedb, vm.Config{})
        if err != nil {
            blockchain.reportBlock(block, receipts, err)
            return err
        }
        err = blockchain.validator.ValidateState(block, blockchain.GetBlockByHash(block.ParentHash()), statedb, receipts, usedGas)
        if err != nil {
            blockchain.reportBlock(block, receipts, err)
            return err
        }
        blockchain.mu.Lock()
        rawdb.WriteTd(blockchain.db, block.Hash(), block.NumberU64(), new(big.Int).Add(block.Difficulty(), blockchain.GetTdByHash(block.ParentHash())))
        rawdb.WriteBlock(blockchain.db, block)
        statedb.Commit(false)
        blockchain.mu.Unlock()
    }
    return nil
}

// testHeaderChainImport tries to process a chain of header, writing them into
// the database if successful.
func testHeaderChainImport(chain []*types.Header, blockchain *BlockChain) error {
    for _, header := range chain {
        // Try and validate the header
        if err := blockchain.engine.VerifyHeader(blockchain, header, false); err != nil {
            return err
        }
        // Manually insert the header into the database, but don't reorganise (allows subsequent testing)
        blockchain.mu.Lock()
        rawdb.WriteTd(blockchain.db, header.Hash(), header.Number.Uint64(), new(big.Int).Add(header.Difficulty, blockchain.GetTdByHash(header.ParentHash)))
        rawdb.WriteHeader(blockchain.db, header)
        blockchain.mu.Unlock()
    }
    return nil
}

func insertChain(done chan bool, blockchain *BlockChain, chain types.Blocks, t *testing.T) {
    _, err := blockchain.InsertChain(chain)
    if err != nil {
        fmt.Println(err)
        t.FailNow()
    }
    done <- true
}

func TestLastBlock(t *testing.T) {
    _, blockchain, err := newCanonical(ethash.NewFaker(), 0, true)
    if err != nil {
        t.Fatalf("failed to create pristine chain: %v", err)
    }
    defer blockchain.Stop()

    blocks := makeBlockChain(blockchain.CurrentBlock(), 1, ethash.NewFullFaker(), blockchain.db, 0)
    if _, err := blockchain.InsertChain(blocks); err != nil {
        t.Fatalf("Failed to insert block: %v", err)
    }
    if blocks[len(blocks)-1].Hash() != rawdb.ReadHeadBlockHash(blockchain.db) {
        t.Fatalf("Write/Get HeadBlockHash failed")
    }
}

// Tests that given a starting canonical chain of a given size, it can be extended
// with various length chains.
func TestExtendCanonicalHeaders(t *testing.T) { testExtendCanonical(t, false) }
func TestExtendCanonicalBlocks(t *testing.T)  { testExtendCanonical(t, true) }

func testExtendCanonical(t *testing.T, full bool) {
    length := 5

    // Make first chain starting from genesis
    _, processor, err := newCanonical(ethash.NewFaker(), length, full)
    if err != nil {
        t.Fatalf("failed to make new canonical chain: %v", err)
    }
    defer processor.Stop()

    // Define the difficulty comparator
    better := func(td1, td2 *big.Int) {
        if td2.Cmp(td1) <= 0 {
            t.Errorf("total difficulty mismatch: have %v, expected more than %v", td2, td1)
        }
    }
    // Start fork from current height
    testFork(t, processor, length, 1, full, better)
    testFork(t, processor, length, 2, full, better)
    testFork(t, processor, length, 5, full, better)
    testFork(t, processor, length, 10, full, better)
}

// Tests that given a starting canonical chain of a given size, creating shorter
// forks do not take canonical ownership.
func TestShorterForkHeaders(t *testing.T) { testShorterFork(t, false) }
func TestShorterForkBlocks(t *testing.T)  { testShorterFork(t, true) }

func testShorterFork(t *testing.T, full bool) {
    length := 10

    // Make first chain starting from genesis
    _, processor, err := newCanonical(ethash.NewFaker(), length, full)
    if err != nil {
        t.Fatalf("failed to make new canonical chain: %v", err)
    }
    defer processor.Stop()

    // Define the difficulty comparator
    worse := func(td1, td2 *big.Int) {
        if td2.Cmp(td1) >= 0 {
            t.Errorf("total difficulty mismatch: have %v, expected less than %v", td2, td1)
        }
    }
    // Sum of numbers must be less than `length` for this to be a shorter fork
    testFork(t, processor, 0, 3, full, worse)
    testFork(t, processor, 0, 7, full, worse)
    testFork(t, processor, 1, 1, full, worse)
    testFork(t, processor, 1, 7, full, worse)
    testFork(t, processor, 5, 3, full, worse)
    testFork(t, processor, 5, 4, full, worse)
}

// Tests that given a starting canonical chain of a given size, creating longer
// forks do take canonical ownership.
func TestLongerForkHeaders(t *testing.T) { testLongerFork(t, false) }
func TestLongerForkBlocks(t *testing.T)  { testLongerFork(t, true) }

func testLongerFork(t *testing.T, full bool) {
    length := 10

    // Make first chain starting from genesis
    _, processor, err := newCanonical(ethash.NewFaker(), length, full)
    if err != nil {
        t.Fatalf("failed to make new canonical chain: %v", err)
    }
    defer processor.Stop()

    // Define the difficulty comparator
    better := func(td1, td2 *big.Int) {
        if td2.Cmp(td1) <= 0 {
            t.Errorf("total difficulty mismatch: have %v, expected more than %v", td2, td1)
        }
    }
    // Sum of numbers must be greater than `length` for this to be a longer fork
    testFork(t, processor, 0, 11, full, better)
    testFork(t, processor, 0, 15, full, better)
    testFork(t, processor, 1, 10, full, better)
    testFork(t, processor, 1, 12, full, better)
    testFork(t, processor, 5, 6, full, better)
    testFork(t, processor, 5, 8, full, better)
}

// Tests that given a starting canonical chain of a given size, creating equal
// forks do take canonical ownership.
func TestEqualForkHeaders(t *testing.T) { testEqualFork(t, false) }
func TestEqualForkBlocks(t *testing.T)  { testEqualFork(t, true) }

func testEqualFork(t *testing.T, full bool) {
    length := 10

    // Make first chain starting from genesis
    _, processor, err := newCanonical(ethash.NewFaker(), length, full)
    if err != nil {
        t.Fatalf("failed to make new canonical chain: %v", err)
    }
    defer processor.Stop()

    // Define the difficulty comparator
    equal := func(td1, td2 *big.Int) {
        if td2.Cmp(td1) != 0 {
            t.Errorf("total difficulty mismatch: have %v, want %v", td2, td1)
        }
    }
    // Sum of numbers must be equal to `length` for this to be an equal fork
    testFork(t, processor, 0, 10, full, equal)
    testFork(t, processor, 1, 9, full, equal)
    testFork(t, processor, 2, 8, full, equal)
    testFork(t, processor, 5, 5, full, equal)
    testFork(t, processor, 6, 4, full, equal)
    testFork(t, processor, 9, 1, full, equal)
}

// Tests that chains missing links do not get accepted by the processor.
func TestBrokenHeaderChain(t *testing.T) { testBrokenChain(t, false) }
func TestBrokenBlockChain(t *testing.T)  { testBrokenChain(t, true) }

func testBrokenChain(t *testing.T, full bool) {
    // Make chain starting from genesis
    db, blockchain, err := newCanonical(ethash.NewFaker(), 10, full)
    if err != nil {
        t.Fatalf("failed to make new canonical chain: %v", err)
    }
    defer blockchain.Stop()

    // Create a forked chain, and try to insert with a missing link
    if full {
        chain := makeBlockChain(blockchain.CurrentBlock(), 5, ethash.NewFaker(), db, forkSeed)[1:]
        if err := testBlockChainImport(chain, blockchain); err == nil {
            t.Errorf("broken block chain not reported")
        }
    } else {
        chain := makeHeaderChain(blockchain.CurrentHeader(), 5, ethash.NewFaker(), db, forkSeed)[1:]
        if err := testHeaderChainImport(chain, blockchain); err == nil {
            t.Errorf("broken header chain not reported")
        }
    }
}

// Tests that reorganising a long difficult chain after a short easy one
// overwrites the canonical numbers and links in the database.
func TestReorgLongHeaders(t *testing.T) { testReorgLong(t, false) }
func TestReorgLongBlocks(t *testing.T)  { testReorgLong(t, true) }

func testReorgLong(t *testing.T, full bool) {
    testReorg(t, []int64{0, 0, -9}, []int64{0, 0, 0, -9}, 393280, full)
}

// Tests that reorganising a short difficult chain after a long easy one
// overwrites the canonical numbers and links in the database.
func TestReorgShortHeaders(t *testing.T) { testReorgShort(t, false) }
func TestReorgShortBlocks(t *testing.T)  { testReorgShort(t, true) }

func testReorgShort(t *testing.T, full bool) {
    // Create a long easy chain vs. a short heavy one. Due to difficulty adjustment
    // we need a fairly long chain of blocks with different difficulties for a short
    // one to become heavyer than a long one. The 96 is an empirical value.
    easy := make([]int64, 96)
    for i := 0; i < len(easy); i++ {
        easy[i] = 60
    }
    diff := make([]int64, len(easy)-1)
    for i := 0; i < len(diff); i++ {
        diff[i] = -9
    }
    testReorg(t, easy, diff, 12615120, full)
}

func testReorg(t *testing.T, first, second []int64, td int64, full bool) {
    // Create a pristine chain and database
    db, blockchain, err := newCanonical(ethash.NewFaker(), 0, full)
    if err != nil {
        t.Fatalf("failed to create pristine chain: %v", err)
    }
    defer blockchain.Stop()

    // Insert an easy and a difficult chain afterwards
    easyBlocks, _ := GenerateChain(params.TestChainConfig, blockchain.CurrentBlock(), ethash.NewFaker(), db, len(first), func(i int, b *BlockGen) {
        b.OffsetTime(first[i])
    })
    diffBlocks, _ := GenerateChain(params.TestChainConfig, blockchain.CurrentBlock(), ethash.NewFaker(), db, len(second), func(i int, b *BlockGen) {
        b.OffsetTime(second[i])
    })
    if full {
        if _, err := blockchain.InsertChain(easyBlocks); err != nil {
            t.Fatalf("failed to insert easy chain: %v", err)
        }
        if _, err := blockchain.InsertChain(diffBlocks); err != nil {
            t.Fatalf("failed to insert difficult chain: %v", err)
        }
    } else {
        easyHeaders := make([]*types.Header, len(easyBlocks))
        for i, block := range easyBlocks {
            easyHeaders[i] = block.Header()
        }
        diffHeaders := make([]*types.Header, len(diffBlocks))
        for i, block := range diffBlocks {
            diffHeaders[i] = block.Header()
        }
        if _, err := blockchain.InsertHeaderChain(easyHeaders, 1); err != nil {
            t.Fatalf("failed to insert easy chain: %v", err)
        }
        if _, err := blockchain.InsertHeaderChain(diffHeaders, 1); err != nil {
            t.Fatalf("failed to insert difficult chain: %v", err)
        }
    }
    // Check that the chain is valid number and link wise
    if full {
        prev := blockchain.CurrentBlock()
        for block := blockchain.GetBlockByNumber(blockchain.CurrentBlock().NumberU64() - 1); block.NumberU64() != 0; prev, block = block, blockchain.GetBlockByNumber(block.NumberU64()-1) {
            if prev.ParentHash() != block.Hash() {
                t.Errorf("parent block hash mismatch: have %x, want %x", prev.ParentHash(), block.Hash())
            }
        }
    } else {
        prev := blockchain.CurrentHeader()
        for header := blockchain.GetHeaderByNumber(blockchain.CurrentHeader().Number.Uint64() - 1); header.Number.Uint64() != 0; prev, header = header, blockchain.GetHeaderByNumber(header.Number.Uint64()-1) {
            if prev.ParentHash != header.Hash() {
                t.Errorf("parent header hash mismatch: have %x, want %x", prev.ParentHash, header.Hash())
            }
        }
    }
    // Make sure the chain total difficulty is the correct one
    want := new(big.Int).Add(blockchain.genesisBlock.Difficulty(), big.NewInt(td))
    if full {
        if have := blockchain.GetTdByHash(blockchain.CurrentBlock().Hash()); have.Cmp(want) != 0 {
            t.Errorf("total difficulty mismatch: have %v, want %v", have, want)
        }
    } else {
        if have := blockchain.GetTdByHash(blockchain.CurrentHeader().Hash()); have.Cmp(want) != 0 {
            t.Errorf("total difficulty mismatch: have %v, want %v", have, want)
        }
    }
}

// Tests that the insertion functions detect banned hashes.
func TestBadHeaderHashes(t *testing.T) { testBadHashes(t, false) }
func TestBadBlockHashes(t *testing.T)  { testBadHashes(t, true) }

func testBadHashes(t *testing.T, full bool) {
    // Create a pristine chain and database
    db, blockchain, err := newCanonical(ethash.NewFaker(), 0, full)
    if err != nil {
        t.Fatalf("failed to create pristine chain: %v", err)
    }
    defer blockchain.Stop()

    // Create a chain, ban a hash and try to import
    if full {
        blocks := makeBlockChain(blockchain.CurrentBlock(), 3, ethash.NewFaker(), db, 10)

        BadHashes[blocks[2].Header().Hash()] = true
        defer func() { delete(BadHashes, blocks[2].Header().Hash()) }()

        _, err = blockchain.InsertChain(blocks)
    } else {
        headers := makeHeaderChain(blockchain.CurrentHeader(), 3, ethash.NewFaker(), db, 10)

        BadHashes[headers[2].Hash()] = true
        defer func() { delete(BadHashes, headers[2].Hash()) }()

        _, err = blockchain.InsertHeaderChain(headers, 1)
    }
    if err != ErrBlacklistedHash {
        t.Errorf("error mismatch: have: %v, want: %v", err, ErrBlacklistedHash)
    }
}

// Tests that bad hashes are detected on boot, and the chain rolled back to a
// good state prior to the bad hash.
func TestReorgBadHeaderHashes(t *testing.T) { testReorgBadHashes(t, false) }
func TestReorgBadBlockHashes(t *testing.T)  { testReorgBadHashes(t, true) }

func testReorgBadHashes(t *testing.T, full bool) {
    // Create a pristine chain and database
    db, blockchain, err := newCanonical(ethash.NewFaker(), 0, full)
    if err != nil {
        t.Fatalf("failed to create pristine chain: %v", err)
    }
    // Create a chain, import and ban afterwards
    headers := makeHeaderChain(blockchain.CurrentHeader(), 4, ethash.NewFaker(), db, 10)
    blocks := makeBlockChain(blockchain.CurrentBlock(), 4, ethash.NewFaker(), db, 10)

    if full {
        if _, err = blockchain.InsertChain(blocks); err != nil {
            t.Errorf("failed to import blocks: %v", err)
        }
        if blockchain.CurrentBlock().Hash() != blocks[3].Hash() {
            t.Errorf("last block hash mismatch: have: %x, want %x", blockchain.CurrentBlock().Hash(), blocks[3].Header().Hash())
        }
        BadHashes[blocks[3].Header().Hash()] = true
        defer func() { delete(BadHashes, blocks[3].Header().Hash()) }()
    } else {
        if _, err = blockchain.InsertHeaderChain(headers, 1); err != nil {
            t.Errorf("failed to import headers: %v", err)
        }
        if blockchain.CurrentHeader().Hash() != headers[3].Hash() {
            t.Errorf("last header hash mismatch: have: %x, want %x", blockchain.CurrentHeader().Hash(), headers[3].Hash())
        }
        BadHashes[headers[3].Hash()] = true
        defer func() { delete(BadHashes, headers[3].Hash()) }()
    }
    blockchain.Stop()

    // Create a new BlockChain and check that it rolled back the state.
    ncm, err := NewBlockChain(blockchain.db, nil, blockchain.chainConfig, ethash.NewFaker(), vm.Config{}, nil)
    if err != nil {
        t.Fatalf("failed to create new chain manager: %v", err)
    }
    if full {
        if ncm.CurrentBlock().Hash() != blocks[2].Header().Hash() {
            t.Errorf("last block hash mismatch: have: %x, want %x", ncm.CurrentBlock().Hash(), blocks[2].Header().Hash())
        }
        if blocks[2].Header().GasLimit != ncm.GasLimit() {
            t.Errorf("last  block gasLimit mismatch: have: %d, want %d", ncm.GasLimit(), blocks[2].Header().GasLimit)
        }
    } else {
        if ncm.CurrentHeader().Hash() != headers[2].Hash() {
            t.Errorf("last header hash mismatch: have: %x, want %x", ncm.CurrentHeader().Hash(), headers[2].Hash())
        }
    }
    ncm.Stop()
}

// Tests chain insertions in the face of one entity containing an invalid nonce.
func TestHeadersInsertNonceError(t *testing.T) { testInsertNonceError(t, false) }
func TestBlocksInsertNonceError(t *testing.T)  { testInsertNonceError(t, true) }

func testInsertNonceError(t *testing.T, full bool) {
    for i := 1; i < 25 && !t.Failed(); i++ {
        // Create a pristine chain and database
        db, blockchain, err := newCanonical(ethash.NewFaker(), 0, full)
        if err != nil {
            t.Fatalf("failed to create pristine chain: %v", err)
        }
        defer blockchain.Stop()

        // Create and insert a chain with a failing nonce
        var (
            failAt  int
            failRes int
            failNum uint64
        )
        if full {
            blocks := makeBlockChain(blockchain.CurrentBlock(), i, ethash.NewFaker(), db, 0)

            failAt = rand.Int() % len(blocks)
            failNum = blocks[failAt].NumberU64()

            blockchain.engine = ethash.NewFakeFailer(failNum)
            failRes, err = blockchain.InsertChain(blocks)
        } else {
            headers := makeHeaderChain(blockchain.CurrentHeader(), i, ethash.NewFaker(), db, 0)

            failAt = rand.Int() % len(headers)
            failNum = headers[failAt].Number.Uint64()

            blockchain.engine = ethash.NewFakeFailer(failNum)
            blockchain.hc.engine = blockchain.engine
            failRes, err = blockchain.InsertHeaderChain(headers, 1)
        }
        // Check that the returned error indicates the failure
        if failRes != failAt {
            t.Errorf("test %d: failure (%v) index mismatch: have %d, want %d", i, err, failRes, failAt)
        }
        // Check that all blocks after the failing block have been inserted
        for j := 0; j < i-failAt; j++ {
            if full {
                if block := blockchain.GetBlockByNumber(failNum + uint64(j)); block != nil {
                    t.Errorf("test %d: invalid block in chain: %v", i, block)
                }
            } else {
                if header := blockchain.GetHeaderByNumber(failNum + uint64(j)); header != nil {
                    t.Errorf("test %d: invalid header in chain: %v", i, header)
                }
            }
        }
    }
}

// Tests that fast importing a block chain produces the same chain data as the
// classical full block processing.
func TestFastVsFullChains(t *testing.T) {
    // Configure and generate a sample block chain
    var (
        gendb   = ethdb.NewMemDatabase()
        key, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        address = crypto.PubkeyToAddress(key.PublicKey)
        funds   = big.NewInt(1000000000)
        gspec   = &Genesis{
            Config: params.TestChainConfig,
            Alloc:  GenesisAlloc{address: {Balance: funds}},
        }
        genesis = gspec.MustCommit(gendb)
        signer  = types.NewEIP155Signer(gspec.Config.ChainID)
    )
    blocks, receipts := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), gendb, 1024, func(i int, block *BlockGen) {
        block.SetCoinbase(common.Address{0x00})

        // If the block number is multiple of 3, send a few bonus transactions to the miner
        if i%3 == 2 {
            for j := 0; j < i%4+1; j++ {
                tx, err := types.SignTx(types.NewTransaction(block.TxNonce(address), common.Address{0x00}, big.NewInt(1000), params.TxGas, nil, nil), signer, key)
                if err != nil {
                    panic(err)
                }
                block.AddTx(tx)
            }
        }
        // If the block number is a multiple of 5, add a few bonus uncles to the block
        if i%5 == 5 {
            block.AddUncle(&types.Header{ParentHash: block.PrevBlock(i - 1).Hash(), Number: big.NewInt(int64(i - 1))})
        }
    })
    // Import the chain as an archive node for the comparison baseline
    archiveDb := ethdb.NewMemDatabase()
    gspec.MustCommit(archiveDb)
    archive, _ := NewBlockChain(archiveDb, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer archive.Stop()

    if n, err := archive.InsertChain(blocks); err != nil {
        t.Fatalf("failed to process block %d: %v", n, err)
    }
    // Fast import the chain as a non-archive node to test
    fastDb := ethdb.NewMemDatabase()
    gspec.MustCommit(fastDb)
    fast, _ := NewBlockChain(fastDb, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer fast.Stop()

    headers := make([]*types.Header, len(blocks))
    for i, block := range blocks {
        headers[i] = block.Header()
    }
    if n, err := fast.InsertHeaderChain(headers, 1); err != nil {
        t.Fatalf("failed to insert header %d: %v", n, err)
    }
    if n, err := fast.InsertReceiptChain(blocks, receipts); err != nil {
        t.Fatalf("failed to insert receipt %d: %v", n, err)
    }
    // Iterate over all chain data components, and cross reference
    for i := 0; i < len(blocks); i++ {
        num, hash := blocks[i].NumberU64(), blocks[i].Hash()

        if ftd, atd := fast.GetTdByHash(hash), archive.GetTdByHash(hash); ftd.Cmp(atd) != 0 {
            t.Errorf("block #%d [%x]: td mismatch: have %v, want %v", num, hash, ftd, atd)
        }
        if fheader, aheader := fast.GetHeaderByHash(hash), archive.GetHeaderByHash(hash); fheader.Hash() != aheader.Hash() {
            t.Errorf("block #%d [%x]: header mismatch: have %v, want %v", num, hash, fheader, aheader)
        }
        if fblock, ablock := fast.GetBlockByHash(hash), archive.GetBlockByHash(hash); fblock.Hash() != ablock.Hash() {
            t.Errorf("block #%d [%x]: block mismatch: have %v, want %v", num, hash, fblock, ablock)
        } else if types.DeriveSha(fblock.Transactions()) != types.DeriveSha(ablock.Transactions()) {
            t.Errorf("block #%d [%x]: transactions mismatch: have %v, want %v", num, hash, fblock.Transactions(), ablock.Transactions())
        } else if types.CalcUncleHash(fblock.Uncles()) != types.CalcUncleHash(ablock.Uncles()) {
            t.Errorf("block #%d [%x]: uncles mismatch: have %v, want %v", num, hash, fblock.Uncles(), ablock.Uncles())
        }
        if freceipts, areceipts := rawdb.ReadReceipts(fastDb, hash, *rawdb.ReadHeaderNumber(fastDb, hash)), rawdb.ReadReceipts(archiveDb, hash, *rawdb.ReadHeaderNumber(archiveDb, hash)); types.DeriveSha(freceipts) != types.DeriveSha(areceipts) {
            t.Errorf("block #%d [%x]: receipts mismatch: have %v, want %v", num, hash, freceipts, areceipts)
        }
    }
    // Check that the canonical chains are the same between the databases
    for i := 0; i < len(blocks)+1; i++ {
        if fhash, ahash := rawdb.ReadCanonicalHash(fastDb, uint64(i)), rawdb.ReadCanonicalHash(archiveDb, uint64(i)); fhash != ahash {
            t.Errorf("block #%d: canonical hash mismatch: have %v, want %v", i, fhash, ahash)
        }
    }
}

// Tests that various import methods move the chain head pointers to the correct
// positions.
func TestLightVsFastVsFullChainHeads(t *testing.T) {
    // Configure and generate a sample block chain
    var (
        gendb   = ethdb.NewMemDatabase()
        key, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        address = crypto.PubkeyToAddress(key.PublicKey)
        funds   = big.NewInt(1000000000)
        gspec   = &Genesis{Config: params.TestChainConfig, Alloc: GenesisAlloc{address: {Balance: funds}}}
        genesis = gspec.MustCommit(gendb)
    )
    height := uint64(1024)
    blocks, receipts := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), gendb, int(height), nil)

    // Configure a subchain to roll back
    remove := []common.Hash{}
    for _, block := range blocks[height/2:] {
        remove = append(remove, block.Hash())
    }
    // Create a small assertion method to check the three heads
    assert := func(t *testing.T, kind string, chain *BlockChain, header uint64, fast uint64, block uint64) {
        if num := chain.CurrentBlock().NumberU64(); num != block {
            t.Errorf("%s head block mismatch: have #%v, want #%v", kind, num, block)
        }
        if num := chain.CurrentFastBlock().NumberU64(); num != fast {
            t.Errorf("%s head fast-block mismatch: have #%v, want #%v", kind, num, fast)
        }
        if num := chain.CurrentHeader().Number.Uint64(); num != header {
            t.Errorf("%s head header mismatch: have #%v, want #%v", kind, num, header)
        }
    }
    // Import the chain as an archive node and ensure all pointers are updated
    archiveDb := ethdb.NewMemDatabase()
    gspec.MustCommit(archiveDb)

    archive, _ := NewBlockChain(archiveDb, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    if n, err := archive.InsertChain(blocks); err != nil {
        t.Fatalf("failed to process block %d: %v", n, err)
    }
    defer archive.Stop()

    assert(t, "archive", archive, height, height, height)
    archive.Rollback(remove)
    assert(t, "archive", archive, height/2, height/2, height/2)

    // Import the chain as a non-archive node and ensure all pointers are updated
    fastDb := ethdb.NewMemDatabase()
    gspec.MustCommit(fastDb)
    fast, _ := NewBlockChain(fastDb, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer fast.Stop()

    headers := make([]*types.Header, len(blocks))
    for i, block := range blocks {
        headers[i] = block.Header()
    }
    if n, err := fast.InsertHeaderChain(headers, 1); err != nil {
        t.Fatalf("failed to insert header %d: %v", n, err)
    }
    if n, err := fast.InsertReceiptChain(blocks, receipts); err != nil {
        t.Fatalf("failed to insert receipt %d: %v", n, err)
    }
    assert(t, "fast", fast, height, height, 0)
    fast.Rollback(remove)
    assert(t, "fast", fast, height/2, height/2, 0)

    // Import the chain as a light node and ensure all pointers are updated
    lightDb := ethdb.NewMemDatabase()
    gspec.MustCommit(lightDb)

    light, _ := NewBlockChain(lightDb, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    if n, err := light.InsertHeaderChain(headers, 1); err != nil {
        t.Fatalf("failed to insert header %d: %v", n, err)
    }
    defer light.Stop()

    assert(t, "light", light, height, 0, 0)
    light.Rollback(remove)
    assert(t, "light", light, height/2, 0, 0)
}

// Tests that chain reorganisations handle transaction removals and reinsertions.
func TestChainTxReorgs(t *testing.T) {
    var (
        key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        key2, _ = crypto.HexToECDSA("8a1f9a8f95be41cd7ccb6168179afb4504aefe388d1e14474d32c45c72ce7b7a")
        key3, _ = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
        addr1   = crypto.PubkeyToAddress(key1.PublicKey)
        addr2   = crypto.PubkeyToAddress(key2.PublicKey)
        addr3   = crypto.PubkeyToAddress(key3.PublicKey)
        db      = ethdb.NewMemDatabase()
        gspec   = &Genesis{
            Config:   params.TestChainConfig,
            GasLimit: 3141592,
            Alloc: GenesisAlloc{
                addr1: {Balance: big.NewInt(1000000)},
                addr2: {Balance: big.NewInt(1000000)},
                addr3: {Balance: big.NewInt(1000000)},
            },
        }
        genesis = gspec.MustCommit(db)
        signer  = types.NewEIP155Signer(gspec.Config.ChainID)
    )

    // Create two transactions shared between the chains:
    //  - postponed: transaction included at a later block in the forked chain
    //  - swapped: transaction included at the same block number in the forked chain
    postponed, _ := types.SignTx(types.NewTransaction(0, addr1, big.NewInt(1000), params.TxGas, nil, nil), signer, key1)
    swapped, _ := types.SignTx(types.NewTransaction(1, addr1, big.NewInt(1000), params.TxGas, nil, nil), signer, key1)

    // Create two transactions that will be dropped by the forked chain:
    //  - pastDrop: transaction dropped retroactively from a past block
    //  - freshDrop: transaction dropped exactly at the block where the reorg is detected
    var pastDrop, freshDrop *types.Transaction

    // Create three transactions that will be added in the forked chain:
    //  - pastAdd:   transaction added before the reorganization is detected
    //  - freshAdd:  transaction added at the exact block the reorg is detected
    //  - futureAdd: transaction added after the reorg has already finished
    var pastAdd, freshAdd, futureAdd *types.Transaction

    chain, _ := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, 3, func(i int, gen *BlockGen) {
        switch i {
        case 0:
            pastDrop, _ = types.SignTx(types.NewTransaction(gen.TxNonce(addr2), addr2, big.NewInt(1000), params.TxGas, nil, nil), signer, key2)

            gen.AddTx(pastDrop)  // This transaction will be dropped in the fork from below the split point
            gen.AddTx(postponed) // This transaction will be postponed till block #3 in the fork

        case 2:
            freshDrop, _ = types.SignTx(types.NewTransaction(gen.TxNonce(addr2), addr2, big.NewInt(1000), params.TxGas, nil, nil), signer, key2)

            gen.AddTx(freshDrop) // This transaction will be dropped in the fork from exactly at the split point
            gen.AddTx(swapped)   // This transaction will be swapped out at the exact height

            gen.OffsetTime(9) // Lower the block difficulty to simulate a weaker chain
        }
    })
    // Import the chain. This runs all block validation rules.
    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    if i, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert original chain[%d]: %v", i, err)
    }
    defer blockchain.Stop()

    // overwrite the old chain
    chain, _ = GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, 5, func(i int, gen *BlockGen) {
        switch i {
        case 0:
            pastAdd, _ = types.SignTx(types.NewTransaction(gen.TxNonce(addr3), addr3, big.NewInt(1000), params.TxGas, nil, nil), signer, key3)
            gen.AddTx(pastAdd) // This transaction needs to be injected during reorg

        case 2:
            gen.AddTx(postponed) // This transaction was postponed from block #1 in the original chain
            gen.AddTx(swapped)   // This transaction was swapped from the exact current spot in the original chain

            freshAdd, _ = types.SignTx(types.NewTransaction(gen.TxNonce(addr3), addr3, big.NewInt(1000), params.TxGas, nil, nil), signer, key3)
            gen.AddTx(freshAdd) // This transaction will be added exactly at reorg time

        case 3:
            futureAdd, _ = types.SignTx(types.NewTransaction(gen.TxNonce(addr3), addr3, big.NewInt(1000), params.TxGas, nil, nil), signer, key3)
            gen.AddTx(futureAdd) // This transaction will be added after a full reorg
        }
    })
    if _, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }

    // removed tx
    for i, tx := range (types.Transactions{pastDrop, freshDrop}) {
        if txn, _, _, _ := rawdb.ReadTransaction(db, tx.Hash()); txn != nil {
            t.Errorf("drop %d: tx %v found while shouldn't have been", i, txn)
        }
        if rcpt, _, _, _ := rawdb.ReadReceipt(db, tx.Hash()); rcpt != nil {
            t.Errorf("drop %d: receipt %v found while shouldn't have been", i, rcpt)
        }
    }
    // added tx
    for i, tx := range (types.Transactions{pastAdd, freshAdd, futureAdd}) {
        if txn, _, _, _ := rawdb.ReadTransaction(db, tx.Hash()); txn == nil {
            t.Errorf("add %d: expected tx to be found", i)
        }
        if rcpt, _, _, _ := rawdb.ReadReceipt(db, tx.Hash()); rcpt == nil {
            t.Errorf("add %d: expected receipt to be found", i)
        }
    }
    // shared tx
    for i, tx := range (types.Transactions{postponed, swapped}) {
        if txn, _, _, _ := rawdb.ReadTransaction(db, tx.Hash()); txn == nil {
            t.Errorf("share %d: expected tx to be found", i)
        }
        if rcpt, _, _, _ := rawdb.ReadReceipt(db, tx.Hash()); rcpt == nil {
            t.Errorf("share %d: expected receipt to be found", i)
        }
    }
}

func TestLogReorgs(t *testing.T) {
    var (
        key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        addr1   = crypto.PubkeyToAddress(key1.PublicKey)
        db      = ethdb.NewMemDatabase()
        // this code generates a log
        code    = common.Hex2Bytes("60606040525b7f24ec1d3ff24c2f6ff210738839dbc339cd45a5294d85c79361016243157aae7b60405180905060405180910390a15b600a8060416000396000f360606040526008565b00")
        gspec   = &Genesis{Config: params.TestChainConfig, Alloc: GenesisAlloc{addr1: {Balance: big.NewInt(10000000000000)}}}
        genesis = gspec.MustCommit(db)
        signer  = types.NewEIP155Signer(gspec.Config.ChainID)
    )

    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer blockchain.Stop()

    rmLogsCh := make(chan RemovedLogsEvent)
    blockchain.SubscribeRemovedLogsEvent(rmLogsCh)
    chain, _ := GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, 2, func(i int, gen *BlockGen) {
        if i == 1 {
            tx, err := types.SignTx(types.NewContractCreation(gen.TxNonce(addr1), new(big.Int), 1000000, new(big.Int), code), signer, key1)
            if err != nil {
                t.Fatalf("failed to create tx: %v", err)
            }
            gen.AddTx(tx)
        }
    })
    if _, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert chain: %v", err)
    }

    chain, _ = GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, 3, func(i int, gen *BlockGen) {})
    if _, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }

    timeout := time.NewTimer(1 * time.Second)
    select {
    case ev := <-rmLogsCh:
        if len(ev.Logs) == 0 {
            t.Error("expected logs")
        }
    case <-timeout.C:
        t.Fatal("Timeout. There is no RemovedLogsEvent has been sent.")
    }
}

func TestLogRebirth(t *testing.T) {
    var (
        key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        addr1   = crypto.PubkeyToAddress(key1.PublicKey)
        db      = ethdb.NewMemDatabase()

        // this code generates a log
        code     = common.Hex2Bytes("60606040525b7f24ec1d3ff24c2f6ff210738839dbc339cd45a5294d85c79361016243157aae7b60405180905060405180910390a15b600a8060416000396000f360606040526008565b00")
        gspec    = &Genesis{Config: params.TestChainConfig, Alloc: GenesisAlloc{addr1: {Balance: big.NewInt(10000000000000)}}}
        genesis  = gspec.MustCommit(db)
        signer   = types.NewEIP155Signer(gspec.Config.ChainID)
        newLogCh = make(chan bool)
    )

    // listenNewLog checks whether the received logs number is equal with expected.
    listenNewLog := func(sink chan []*types.Log, expect int) {
        cnt := 0
        for {
            select {
            case logs := <-sink:
                cnt += len(logs)
            case <-time.NewTimer(5 * time.Second).C:
                // new logs timeout
                newLogCh <- false
                return
            }
            if cnt == expect {
                break
            } else if cnt > expect {
                // redundant logs received
                newLogCh <- false
                return
            }
        }
        select {
        case <-sink:
            // redundant logs received
            newLogCh <- false
        case <-time.NewTimer(100 * time.Millisecond).C:
            newLogCh <- true
        }
    }

    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer blockchain.Stop()

    logsCh := make(chan []*types.Log)
    blockchain.SubscribeLogsEvent(logsCh)

    rmLogsCh := make(chan RemovedLogsEvent)
    blockchain.SubscribeRemovedLogsEvent(rmLogsCh)

    chain, _ := GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, 2, func(i int, gen *BlockGen) {
        if i == 1 {
            tx, err := types.SignTx(types.NewContractCreation(gen.TxNonce(addr1), new(big.Int), 1000000, new(big.Int), code), signer, key1)
            if err != nil {
                t.Fatalf("failed to create tx: %v", err)
            }
            gen.AddTx(tx)
        }
    })

    // Spawn a goroutine to receive log events
    go listenNewLog(logsCh, 1)
    if _, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert chain: %v", err)
    }
    if !<-newLogCh {
        t.Fatalf("failed to receive new log event")
    }

    // Generate long reorg chain
    forkChain, _ := GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, 2, func(i int, gen *BlockGen) {
        if i == 1 {
            tx, err := types.SignTx(types.NewContractCreation(gen.TxNonce(addr1), new(big.Int), 1000000, new(big.Int), code), signer, key1)
            if err != nil {
                t.Fatalf("failed to create tx: %v", err)
            }
            gen.AddTx(tx)
            // Higher block difficulty
            gen.OffsetTime(-9)
        }
    })

    // Spawn a goroutine to receive log events
    go listenNewLog(logsCh, 1)
    if _, err := blockchain.InsertChain(forkChain); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }
    if !<-newLogCh {
        t.Fatalf("failed to receive new log event")
    }
    // Ensure removedLog events received
    select {
    case ev := <-rmLogsCh:
        if len(ev.Logs) == 0 {
            t.Error("expected logs")
        }
    case <-time.NewTimer(1 * time.Second).C:
        t.Fatal("Timeout. There is no RemovedLogsEvent has been sent.")
    }

    newBlocks, _ := GenerateChain(params.TestChainConfig, chain[len(chain)-1], ethash.NewFaker(), db, 1, func(i int, gen *BlockGen) {})
    go listenNewLog(logsCh, 1)
    if _, err := blockchain.InsertChain(newBlocks); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }
    // Ensure removedLog events received
    select {
    case ev := <-rmLogsCh:
        if len(ev.Logs) == 0 {
            t.Error("expected logs")
        }
    case <-time.NewTimer(1 * time.Second).C:
        t.Fatal("Timeout. There is no RemovedLogsEvent has been sent.")
    }
    // Rebirth logs should omit a newLogEvent
    if !<-newLogCh {
        t.Fatalf("failed to receive new log event")
    }
}

func TestSideLogRebirth(t *testing.T) {
    var (
        key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        addr1   = crypto.PubkeyToAddress(key1.PublicKey)
        db      = ethdb.NewMemDatabase()

        // this code generates a log
        code     = common.Hex2Bytes("60606040525b7f24ec1d3ff24c2f6ff210738839dbc339cd45a5294d85c79361016243157aae7b60405180905060405180910390a15b600a8060416000396000f360606040526008565b00")
        gspec    = &Genesis{Config: params.TestChainConfig, Alloc: GenesisAlloc{addr1: {Balance: big.NewInt(10000000000000)}}}
        genesis  = gspec.MustCommit(db)
        signer   = types.NewEIP155Signer(gspec.Config.ChainID)
        newLogCh = make(chan bool)
    )

    // listenNewLog checks whether the received logs number is equal with expected.
    listenNewLog := func(sink chan []*types.Log, expect int) {
        cnt := 0
        for {
            select {
            case logs := <-sink:
                cnt += len(logs)
            case <-time.NewTimer(5 * time.Second).C:
                // new logs timeout
                newLogCh <- false
                return
            }
            if cnt == expect {
                break
            } else if cnt > expect {
                // redundant logs received
                newLogCh <- false
                return
            }
        }
        select {
        case <-sink:
            // redundant logs received
            newLogCh <- false
        case <-time.NewTimer(100 * time.Millisecond).C:
            newLogCh <- true
        }
    }

    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer blockchain.Stop()

    logsCh := make(chan []*types.Log)
    blockchain.SubscribeLogsEvent(logsCh)

    chain, _ := GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, 2, func(i int, gen *BlockGen) {
        if i == 1 {
            // Higher block difficulty
            gen.OffsetTime(-9)
        }
    })
    if _, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }

    // Generate side chain with lower difficulty
    sideChain, _ := GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, 2, func(i int, gen *BlockGen) {
        if i == 1 {
            tx, err := types.SignTx(types.NewContractCreation(gen.TxNonce(addr1), new(big.Int), 1000000, new(big.Int), code), signer, key1)
            if err != nil {
                t.Fatalf("failed to create tx: %v", err)
            }
            gen.AddTx(tx)
        }
    })
    if _, err := blockchain.InsertChain(sideChain); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }

    // Generate a new block based on side chain
    newBlocks, _ := GenerateChain(params.TestChainConfig, sideChain[len(sideChain)-1], ethash.NewFaker(), db, 1, func(i int, gen *BlockGen) {})
    go listenNewLog(logsCh, 1)
    if _, err := blockchain.InsertChain(newBlocks); err != nil {
        t.Fatalf("failed to insert forked chain: %v", err)
    }
    // Rebirth logs should omit a newLogEvent
    if !<-newLogCh {
        t.Fatalf("failed to receive new log event")
    }
}

func TestReorgSideEvent(t *testing.T) {
    var (
        db      = ethdb.NewMemDatabase()
        key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        addr1   = crypto.PubkeyToAddress(key1.PublicKey)
        gspec   = &Genesis{
            Config: params.TestChainConfig,
            Alloc:  GenesisAlloc{addr1: {Balance: big.NewInt(10000000000000)}},
        }
        genesis = gspec.MustCommit(db)
        signer  = types.NewEIP155Signer(gspec.Config.ChainID)
    )

    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer blockchain.Stop()

    chain, _ := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, 3, func(i int, gen *BlockGen) {})
    if _, err := blockchain.InsertChain(chain); err != nil {
        t.Fatalf("failed to insert chain: %v", err)
    }

    replacementBlocks, _ := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, 4, func(i int, gen *BlockGen) {
        tx, err := types.SignTx(types.NewContractCreation(gen.TxNonce(addr1), new(big.Int), 1000000, new(big.Int), nil), signer, key1)
        if i == 2 {
            gen.OffsetTime(-9)
        }
        if err != nil {
            t.Fatalf("failed to create tx: %v", err)
        }
        gen.AddTx(tx)
    })
    chainSideCh := make(chan ChainSideEvent, 64)
    blockchain.SubscribeChainSideEvent(chainSideCh)
    if _, err := blockchain.InsertChain(replacementBlocks); err != nil {
        t.Fatalf("failed to insert chain: %v", err)
    }

    // first two block of the secondary chain are for a brief moment considered
    // side chains because up to that point the first one is considered the
    // heavier chain.
    expectedSideHashes := map[common.Hash]bool{
        replacementBlocks[0].Hash(): true,
        replacementBlocks[1].Hash(): true,
        chain[0].Hash():             true,
        chain[1].Hash():             true,
        chain[2].Hash():             true,
    }

    i := 0

    const timeoutDura = 10 * time.Second
    timeout := time.NewTimer(timeoutDura)
done:
    for {
        select {
        case ev := <-chainSideCh:
            block := ev.Block
            if _, ok := expectedSideHashes[block.Hash()]; !ok {
                t.Errorf("%d: didn't expect %x to be in side chain", i, block.Hash())
            }
            i++

            if i == len(expectedSideHashes) {
                timeout.Stop()

                break done
            }
            timeout.Reset(timeoutDura)

        case <-timeout.C:
            t.Fatal("Timeout. Possibly not all blocks were triggered for sideevent")
        }
    }

    // make sure no more events are fired
    select {
    case e := <-chainSideCh:
        t.Errorf("unexpected event fired: %v", e)
    case <-time.After(250 * time.Millisecond):
    }

}

// Tests if the canonical block can be fetched from the database during chain insertion.
func TestCanonicalBlockRetrieval(t *testing.T) {
    _, blockchain, err := newCanonical(ethash.NewFaker(), 0, true)
    if err != nil {
        t.Fatalf("failed to create pristine chain: %v", err)
    }
    defer blockchain.Stop()

    chain, _ := GenerateChain(blockchain.chainConfig, blockchain.genesisBlock, ethash.NewFaker(), blockchain.db, 10, func(i int, gen *BlockGen) {})

    var pend sync.WaitGroup
    pend.Add(len(chain))

    for i := range chain {
        go func(block *types.Block) {
            defer pend.Done()

            // try to retrieve a block by its canonical hash and see if the block data can be retrieved.
            for {
                ch := rawdb.ReadCanonicalHash(blockchain.db, block.NumberU64())
                if ch == (common.Hash{}) {
                    continue // busy wait for canonical hash to be written
                }
                if ch != block.Hash() {
                    t.Fatalf("unknown canonical hash, want %s, got %s", block.Hash().Hex(), ch.Hex())
                }
                fb := rawdb.ReadBlock(blockchain.db, ch, block.NumberU64())
                if fb == nil {
                    t.Fatalf("unable to retrieve block %d for canonical hash: %s", block.NumberU64(), ch.Hex())
                }
                if fb.Hash() != block.Hash() {
                    t.Fatalf("invalid block hash for block %d, want %s, got %s", block.NumberU64(), block.Hash().Hex(), fb.Hash().Hex())
                }
                return
            }
        }(chain[i])

        if _, err := blockchain.InsertChain(types.Blocks{chain[i]}); err != nil {
            t.Fatalf("failed to insert block %d: %v", i, err)
        }
    }
    pend.Wait()
}

func TestEIP155Transition(t *testing.T) {
    // Configure and generate a sample block chain
    var (
        db         = ethdb.NewMemDatabase()
        key, _     = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        address    = crypto.PubkeyToAddress(key.PublicKey)
        funds      = big.NewInt(1000000000)
        deleteAddr = common.Address{1}
        gspec      = &Genesis{
            Config: &params.ChainConfig{ChainID: big.NewInt(1), EIP155Block: big.NewInt(2), HomesteadBlock: new(big.Int)},
            Alloc:  GenesisAlloc{address: {Balance: funds}, deleteAddr: {Balance: new(big.Int)}},
        }
    )

    genesis := gspec.MustCommit(db)

    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer blockchain.Stop()

    blocks, _ := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, 4, func(i int, block *BlockGen) {
        var (
            tx      *types.Transaction
            err     error
            basicTx = func(signer types.Signer) (*types.Transaction, error) {
                return types.SignTx(types.NewTransaction(block.TxNonce(address), common.Address{}, new(big.Int), 21000, new(big.Int), nil), signer, key)
            }
        )
        switch i {
        case 0:
            tx, err = basicTx(types.HomesteadSigner{})
            if err != nil {
                t.Fatal(err)
            }
            block.AddTx(tx)
        case 2:
            tx, err = basicTx(types.HomesteadSigner{})
            if err != nil {
                t.Fatal(err)
            }
            block.AddTx(tx)

            tx, err = basicTx(types.NewEIP155Signer(gspec.Config.ChainID))
            if err != nil {
                t.Fatal(err)
            }
            block.AddTx(tx)
        case 3:
            tx, err = basicTx(types.HomesteadSigner{})
            if err != nil {
                t.Fatal(err)
            }
            block.AddTx(tx)

            tx, err = basicTx(types.NewEIP155Signer(gspec.Config.ChainID))
            if err != nil {
                t.Fatal(err)
            }
            block.AddTx(tx)
        }
    })

    if _, err := blockchain.InsertChain(blocks); err != nil {
        t.Fatal(err)
    }
    block := blockchain.GetBlockByNumber(1)
    if block.Transactions()[0].Protected() {
        t.Error("Expected block[0].txs[0] to not be replay protected")
    }

    block = blockchain.GetBlockByNumber(3)
    if block.Transactions()[0].Protected() {
        t.Error("Expected block[3].txs[0] to not be replay protected")
    }
    if !block.Transactions()[1].Protected() {
        t.Error("Expected block[3].txs[1] to be replay protected")
    }
    if _, err := blockchain.InsertChain(blocks[4:]); err != nil {
        t.Fatal(err)
    }

    // generate an invalid chain id transaction
    config := &params.ChainConfig{ChainID: big.NewInt(2), EIP155Block: big.NewInt(2), HomesteadBlock: new(big.Int)}
    blocks, _ = GenerateChain(config, blocks[len(blocks)-1], ethash.NewFaker(), db, 4, func(i int, block *BlockGen) {
        var (
            tx      *types.Transaction
            err     error
            basicTx = func(signer types.Signer) (*types.Transaction, error) {
                return types.SignTx(types.NewTransaction(block.TxNonce(address), common.Address{}, new(big.Int), 21000, new(big.Int), nil), signer, key)
            }
        )
        if i == 0 {
            tx, err = basicTx(types.NewEIP155Signer(big.NewInt(2)))
            if err != nil {
                t.Fatal(err)
            }
            block.AddTx(tx)
        }
    })
    _, err := blockchain.InsertChain(blocks)
    if err != types.ErrInvalidChainId {
        t.Error("expected error:", types.ErrInvalidChainId)
    }
}

func TestEIP161AccountRemoval(t *testing.T) {
    // Configure and generate a sample block chain
    var (
        db      = ethdb.NewMemDatabase()
        key, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        address = crypto.PubkeyToAddress(key.PublicKey)
        funds   = big.NewInt(1000000000)
        theAddr = common.Address{1}
        gspec   = &Genesis{
            Config: &params.ChainConfig{
                ChainID:        big.NewInt(1),
                HomesteadBlock: new(big.Int),
                EIP155Block:    new(big.Int),
                EIP158Block:    big.NewInt(2),
            },
            Alloc: GenesisAlloc{address: {Balance: funds}},
        }
    )

    gspec.Config.Dexcon = params.TestChainConfig.Dexcon
    genesis := gspec.MustCommit(db)
    blockchain, _ := NewBlockChain(db, nil, gspec.Config, ethash.NewFaker(), vm.Config{}, nil)
    defer blockchain.Stop()

    blocks, _ := GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, 3, func(i int, block *BlockGen) {
        var (
            tx     *types.Transaction
            err    error
            signer = types.NewEIP155Signer(gspec.Config.ChainID)
        )
        switch i {
        case 0:
            tx, err = types.SignTx(types.NewTransaction(block.TxNonce(address), theAddr, new(big.Int), 21000, new(big.Int), nil), signer, key)
        case 1:
            tx, err = types.SignTx(types.NewTransaction(block.TxNonce(address), theAddr, new(big.Int), 21000, new(big.Int), nil), signer, key)
        case 2:
            tx, err = types.SignTx(types.NewTransaction(block.TxNonce(address), theAddr, new(big.Int), 21000, new(big.Int), nil), signer, key)
        }
        if err != nil {
            t.Fatal(err)
        }
        block.AddTx(tx)
    })
    // account must exist pre eip 161
    if _, err := blockchain.InsertChain(types.Blocks{blocks[0]}); err != nil {
        t.Fatal(err)
    }
    if st, _ := blockchain.State(); !st.Exist(theAddr) {
        t.Error("expected account to exist")
    }

    // account needs to be deleted post eip 161
    if _, err := blockchain.InsertChain(types.Blocks{blocks[1]}); err != nil {
        t.Fatal(err)
    }
    if st, _ := blockchain.State(); st.Exist(theAddr) {
        t.Error("account should not exist")
    }

    // account musn't be created post eip 161
    if _, err := blockchain.InsertChain(types.Blocks{blocks[2]}); err != nil {
        t.Fatal(err)
    }
    if st, _ := blockchain.State(); st.Exist(theAddr) {
        t.Error("account should not exist")
    }
}

// This is a regression test (i.e. as weird as it is, don't delete it ever), which
// tests that under weird reorg conditions the blockchain and its internal header-
// chain return the same latest block/header.
//
// https://github.com/dexon-foundation/dexon/pull/15941
func TestBlockchainHeaderchainReorgConsistency(t *testing.T) {
    // Generate a canonical chain to act as the main dataset
    engine := ethash.NewFaker()

    db := ethdb.NewMemDatabase()
    gspec := &Genesis{
        Config: params.TestnetChainConfig,
    }
    genesis := gspec.MustCommit(db)
    blocks, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, 64, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{1}) })

    // Generate a bunch of fork blocks, each side forking from the canonical chain
    forks := make([]*types.Block, len(blocks))
    for i := 0; i < len(forks); i++ {
        parent := genesis
        if i > 0 {
            parent = blocks[i-1]
        }
        fork, _ := GenerateChain(params.TestChainConfig, parent, engine, db, 1, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{2}) })
        forks[i] = fork[0]
    }
    // Import the canonical and fork chain side by side, verifying the current block
    // and current header consistency
    diskdb := ethdb.NewMemDatabase()
    gspec.MustCommit(diskdb)

    chain, err := NewBlockChain(diskdb, nil, params.TestChainConfig, engine, vm.Config{}, nil)
    if err != nil {
        t.Fatalf("failed to create tester chain: %v", err)
    }
    for i := 0; i < len(blocks); i++ {
        if _, err := chain.InsertChain(blocks[i : i+1]); err != nil {
            t.Fatalf("block %d: failed to insert into chain: %v", i, err)
        }
        if chain.CurrentBlock().Hash() != chain.CurrentHeader().Hash() {
            t.Errorf("block %d: current block/header mismatch: block #%d [%x…], header #%d [%x…]", i, chain.CurrentBlock().Number(), chain.CurrentBlock().Hash().Bytes()[:4], chain.CurrentHeader().Number, chain.CurrentHeader().Hash().Bytes()[:4])
        }
        if _, err := chain.InsertChain(forks[i : i+1]); err != nil {
            t.Fatalf(" fork %d: failed to insert into chain: %v", i, err)
        }
        if chain.CurrentBlock().Hash() != chain.CurrentHeader().Hash() {
            t.Errorf(" fork %d: current block/header mismatch: block #%d [%x…], header #%d [%x…]", i, chain.CurrentBlock().Number(), chain.CurrentBlock().Hash().Bytes()[:4], chain.CurrentHeader().Number, chain.CurrentHeader().Hash().Bytes()[:4])
        }
    }
}

// Tests that importing small side forks doesn't leave junk in the trie database
// cache (which would eventually cause memory issues).
func TestTrieForkGC(t *testing.T) {
    // Generate a canonical chain to act as the main dataset
    engine := ethash.NewFaker()

    db := ethdb.NewMemDatabase()
    gspec := &Genesis{
        Config: params.TestnetChainConfig,
    }
    genesis := gspec.MustCommit(db)
    blocks, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, 2*triesInMemory, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{1}) })

    // Generate a bunch of fork blocks, each side forking from the canonical chain
    forks := make([]*types.Block, len(blocks))
    for i := 0; i < len(forks); i++ {
        parent := genesis
        if i > 0 {
            parent = blocks[i-1]
        }
        fork, _ := GenerateChain(params.TestChainConfig, parent, engine, db, 1, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{2}) })
        forks[i] = fork[0]
    }
    // Import the canonical and fork chain side by side, forcing the trie cache to cache both
    diskdb := ethdb.NewMemDatabase()
    gspec.MustCommit(diskdb)

    chain, err := NewBlockChain(diskdb, nil, params.TestChainConfig, engine, vm.Config{}, nil)
    if err != nil {
        t.Fatalf("failed to create tester chain: %v", err)
    }
    for i := 0; i < len(blocks); i++ {
        if _, err := chain.InsertChain(blocks[i : i+1]); err != nil {
            t.Fatalf("block %d: failed to insert into chain: %v", i, err)
        }
        if _, err := chain.InsertChain(forks[i : i+1]); err != nil {
            t.Fatalf("fork %d: failed to insert into chain: %v", i, err)
        }
    }
    // Dereference all the recent tries and ensure no past trie is left in
    for i := 0; i < triesInMemory; i++ {
        chain.stateCache.TrieDB().Dereference(blocks[len(blocks)-1-i].Root())
        chain.stateCache.TrieDB().Dereference(forks[len(blocks)-1-i].Root())
    }
    if len(chain.stateCache.TrieDB().Nodes()) > 0 {
        t.Fatalf("stale tries still alive after garbase collection")
    }
}

// Tests that doing large reorgs works even if the state associated with the
// forking point is not available any more.
func TestLargeReorgTrieGC(t *testing.T) {
    // Generate the original common chain segment and the two competing forks
    engine := ethash.NewFaker()

    db := ethdb.NewMemDatabase()
    gspec := &Genesis{
        Config: params.TestnetChainConfig,
    }
    genesis := gspec.MustCommit(db)

    shared, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, 64, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{1}) })
    original, _ := GenerateChain(params.TestChainConfig, shared[len(shared)-1], engine, db, 2*triesInMemory, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{2}) })
    competitor, _ := GenerateChain(params.TestChainConfig, shared[len(shared)-1], engine, db, 2*triesInMemory+1, func(i int, b *BlockGen) { b.SetCoinbase(common.Address{3}) })

    // Import the shared chain and the original canonical one
    diskdb := ethdb.NewMemDatabase()
    gspec.MustCommit(diskdb)

    chain, err := NewBlockChain(diskdb, nil, params.TestChainConfig, engine, vm.Config{}, nil)
    if err != nil {
        t.Fatalf("failed to create tester chain: %v", err)
    }
    if _, err := chain.InsertChain(shared); err != nil {
        t.Fatalf("failed to insert shared chain: %v", err)
    }
    if _, err := chain.InsertChain(original); err != nil {
        t.Fatalf("failed to insert original chain: %v", err)
    }
    // Ensure that the state associated with the forking point is pruned away
    if node, _ := chain.stateCache.TrieDB().Node(shared[len(shared)-1].Root()); node != nil {
        t.Fatalf("common-but-old ancestor still cache")
    }
    // Import the competitor chain without exceeding the canonical's TD and ensure
    // we have not processed any of the blocks (protection against malicious blocks)
    if _, err := chain.InsertChain(competitor[:len(competitor)-2]); err != nil {
        t.Fatalf("failed to insert competitor chain: %v", err)
    }
    for i, block := range competitor[:len(competitor)-2] {
        if node, _ := chain.stateCache.TrieDB().Node(block.Root()); node != nil {
            t.Fatalf("competitor %d: low TD chain became processed", i)
        }
    }
    // Import the head of the competitor chain, triggering the reorg and ensure we
    // successfully reprocess all the stashed away blocks.
    if _, err := chain.InsertChain(competitor[len(competitor)-2:]); err != nil {
        t.Fatalf("failed to finalize competitor chain: %v", err)
    }
    for i, block := range competitor[:len(competitor)-triesInMemory] {
        if node, _ := chain.stateCache.TrieDB().Node(block.Root()); node != nil {
            t.Fatalf("competitor %d: competing chain state missing", i)
        }
    }
}

// Benchmarks large blocks with value transfers to non-existing accounts
func benchmarkLargeNumberOfValueToNonexisting(b *testing.B, numTxs, numBlocks int, recipientFn func(uint64) common.Address, dataFn func(uint64) []byte) {
    var (
        signer          = types.HomesteadSigner{}
        testBankKey, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
        testBankAddress = crypto.PubkeyToAddress(testBankKey.PublicKey)
        bankFunds       = big.NewInt(100000000000000000)
        gspec           = Genesis{
            Config: params.TestChainConfig,
            Alloc: GenesisAlloc{
                testBankAddress: {Balance: bankFunds},
                common.HexToAddress("0xc0de"): {
                    Code:    []byte{0x60, 0x01, 0x50},
                    Balance: big.NewInt(0),
                }, // push 1, pop
            },
            GasLimit: 100e6, // 100 M
        }
    )
    // Generate the original common chain segment and the two competing forks
    engine := ethash.NewFaker()
    db := ethdb.NewMemDatabase()
    genesis := gspec.MustCommit(db)

    blockGenerator := func(i int, block *BlockGen) {
        block.SetCoinbase(common.Address{1})
        for txi := 0; txi < numTxs; txi++ {
            uniq := uint64(i*numTxs + txi)
            recipient := recipientFn(uniq)
            //recipient := common.BigToAddress(big.NewInt(0).SetUint64(1337 + uniq))
            tx, err := types.SignTx(types.NewTransaction(uniq, recipient, big.NewInt(1), params.TxGas, big.NewInt(1), nil), signer, testBankKey)
            if err != nil {
                b.Error(err)
            }
            block.AddTx(tx)
        }
    }

    shared, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, numBlocks, blockGenerator)
    b.StopTimer()
    b.ResetTimer()
    for i := 0; i < b.N; i++ {
        // Import the shared chain and the original canonical one
        diskdb := ethdb.NewMemDatabase()
        gspec.MustCommit(diskdb)

        chain, err := NewBlockChain(diskdb, nil, params.TestChainConfig, engine, vm.Config{}, nil)
        if err != nil {
            b.Fatalf("failed to create tester chain: %v", err)
        }
        b.StartTimer()
        if _, err := chain.InsertChain(shared); err != nil {
            b.Fatalf("failed to insert shared chain: %v", err)
        }
        b.StopTimer()
        if got := chain.CurrentBlock().Transactions().Len(); got != numTxs*numBlocks {
            b.Fatalf("Transactions were not included, expected %d, got %d", (numTxs * numBlocks), got)

        }
    }
}
func BenchmarkBlockChain_1x1000ValueTransferToNonexisting(b *testing.B) {
    var (
        numTxs    = 1000
        numBlocks = 1
    )

    recipientFn := func(nonce uint64) common.Address {
        return common.BigToAddress(big.NewInt(0).SetUint64(1337 + nonce))
    }
    dataFn := func(nonce uint64) []byte {
        return nil
    }

    benchmarkLargeNumberOfValueToNonexisting(b, numTxs, numBlocks, recipientFn, dataFn)
}
func BenchmarkBlockChain_1x1000ValueTransferToExisting(b *testing.B) {
    var (
        numTxs    = 1000
        numBlocks = 1
    )
    b.StopTimer()
    b.ResetTimer()

    recipientFn := func(nonce uint64) common.Address {
        return common.BigToAddress(big.NewInt(0).SetUint64(1337))
    }
    dataFn := func(nonce uint64) []byte {
        return nil
    }

    benchmarkLargeNumberOfValueToNonexisting(b, numTxs, numBlocks, recipientFn, dataFn)
}
func BenchmarkBlockChain_1x1000Executions(b *testing.B) {
    var (
        numTxs    = 1000
        numBlocks = 1
    )
    b.StopTimer()
    b.ResetTimer()

    recipientFn := func(nonce uint64) common.Address {
        return common.BigToAddress(big.NewInt(0).SetUint64(0xc0de))
    }
    dataFn := func(nonce uint64) []byte {
        return nil
    }

    benchmarkLargeNumberOfValueToNonexisting(b, numTxs, numBlocks, recipientFn, dataFn)
}

// Tests that importing a very large side fork, which is larger than the canon chain,
// but where the difficulty per block is kept low: this means that it will not
// overtake the 'canon' chain until after it's passed canon by about 200 blocks.
//
// Details at:
//  - https://github.com/dexon-foundation/dexon/issues/18977
//  - https://github.com/dexon-foundation/dexon/pull/18988
func TestLowDiffLongChain(t *testing.T) {
    // Generate a canonical chain to act as the main dataset
    engine := ethash.NewFaker()
    db := ethdb.NewMemDatabase()
    genesis := new(Genesis).MustCommit(db)

    // We must use a pretty long chain to ensure that the fork doesn't overtake us
    // until after at least 128 blocks post tip
    blocks, _ := GenerateChain(params.TestChainConfig, genesis, engine, db, 6*triesInMemory, func(i int, b *BlockGen) {
        b.SetCoinbase(common.Address{1})
        b.OffsetTime(-9)
    })

    // Import the canonical chain
    diskdb := ethdb.NewMemDatabase()
    new(Genesis).MustCommit(diskdb)

    chain, err := NewBlockChain(diskdb, nil, params.TestChainConfig, engine, vm.Config{}, nil)
    if err != nil {
        t.Fatalf("failed to create tester chain: %v", err)
    }
    if n, err := chain.InsertChain(blocks); err != nil {
        t.Fatalf("block %d: failed to insert into chain: %v", n, err)
    }
    // Generate fork chain, starting from an early block
    parent := blocks[10]
    fork, _ := GenerateChain(params.TestChainConfig, parent, engine, db, 8*triesInMemory, func(i int, b *BlockGen) {
        b.SetCoinbase(common.Address{2})
    })

    // And now import the fork
    if i, err := chain.InsertChain(fork); err != nil {
        t.Fatalf("block %d: failed to insert into chain: %v", i, err)
    }
    head := chain.CurrentBlock()
    if got := fork[len(fork)-1].Hash(); got != head.Hash() {
        t.Fatalf("head wrong, expected %x got %x", head.Hash(), got)
    }
    // Sanity check that all the canonical numbers are present
    header := chain.CurrentHeader()
    for number := head.NumberU64(); number > 0; number-- {
        if hash := chain.GetHeaderByNumber(number).Hash(); hash != header.Hash() {
            t.Fatalf("header %d: canonical hash mismatch: have %x, want %x", number, hash, header.Hash())
        }
        header = chain.GetHeader(header.ParentHash, number-1)
    }
}