// 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 trie

import (
	"bytes"
	"encoding/binary"
	"errors"
	"fmt"
	"math/big"
	"math/rand"
	"reflect"
	"testing"
	"testing/quick"

	"github.com/davecgh/go-spew/spew"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/rawdb"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/rlp"
)

func init() {
	spew.Config.Indent = "    "
	spew.Config.DisableMethods = false
}

func TestEmptyTrie(t *testing.T) {
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	res := trie.Hash()
	exp := types.EmptyRootHash
	if res != exp {
		t.Errorf("expected %x got %x", exp, res)
	}
}

func TestNull(t *testing.T) {
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	key := make([]byte, 32)
	value := []byte("test")
	trie.Update(key, value)
	if !bytes.Equal(trie.Get(key), value) {
		t.Fatal("wrong value")
	}
}

func TestMissingRoot(t *testing.T) {
	root := common.HexToHash("0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33")
	trie, err := NewAccountTrie(TrieID(root), NewDatabase(rawdb.NewMemoryDatabase()))
	if trie != nil {
		t.Error("New returned non-nil trie for invalid root")
	}
	if _, ok := err.(*MissingNodeError); !ok {
		t.Errorf("New returned wrong error: %v", err)
	}
}

func TestMissingNodeMemonly(t *testing.T) { testMissingNode(t, true) }

func testMissingNode(t *testing.T, memonly bool) {
	diskdb := rawdb.NewMemoryDatabase()
	triedb := NewDatabase(diskdb)

	trie := NewEmpty(triedb)
	updateString(trie, "120000", "qwerqwerqwerqwerqwerqwerqwerqwer")
	updateString(trie, "123456", "asdfasdfasdfasdfasdfasdfasdfasdf")
	root, nodes := trie.Commit(false)
	triedb.Update(NewWithNodeSet(nodes))

	trie, _ = NewAccountTrie(TrieID(root), triedb)
	_, err := trie.TryGet([]byte("120000"))
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	_, err = trie.TryGet([]byte("120099"))
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	_, err = trie.TryGet([]byte("123456"))
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	err = trie.TryUpdate([]byte("120099"), []byte("zxcvzxcvzxcvzxcvzxcvzxcvzxcvzxcv"))
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	err = trie.TryDelete([]byte("123456"))
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}

	hash := common.HexToHash("0xe1d943cc8f061a0c0b98162830b970395ac9315654824bf21b73b891365262f9")
	if memonly {
		delete(triedb.dirties, hash)
	} else {
		diskdb.Delete(hash[:])
	}

	trie, _ = NewAccountTrie(TrieID(root), triedb)
	_, err = trie.TryGet([]byte("120000"))
	if _, ok := err.(*MissingNodeError); !ok {
		t.Errorf("Wrong error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	_, err = trie.TryGet([]byte("120099"))
	if _, ok := err.(*MissingNodeError); !ok {
		t.Errorf("Wrong error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	_, err = trie.TryGet([]byte("123456"))
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	err = trie.TryUpdate([]byte("120099"), []byte("zxcv"))
	if _, ok := err.(*MissingNodeError); !ok {
		t.Errorf("Wrong error: %v", err)
	}
	trie, _ = NewAccountTrie(TrieID(root), triedb)
	err = trie.TryDelete([]byte("123456"))
	if _, ok := err.(*MissingNodeError); !ok {
		t.Errorf("Wrong error: %v", err)
	}
}

func TestInsert(t *testing.T) {
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))

	updateString(trie, "doe", "reindeer")
	updateString(trie, "dog", "puppy")
	updateString(trie, "dogglesworth", "cat")

	exp := common.HexToHash("8aad789dff2f538bca5d8ea56e8abe10f4c7ba3a5dea95fea4cd6e7c3a1168d3")
	root := trie.Hash()
	if root != exp {
		t.Errorf("case 1: exp %x got %x", exp, root)
	}

	trie = NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	updateString(trie, "A", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")

	exp = common.HexToHash("d23786fb4a010da3ce639d66d5e904a11dbc02746d1ce25029e53290cabf28ab")
	root, _ = trie.Commit(false)
	if root != exp {
		t.Errorf("case 2: exp %x got %x", exp, root)
	}
}

func TestGet(t *testing.T) {
	db := NewDatabase(rawdb.NewMemoryDatabase())
	trie := NewEmpty(db)
	updateString(trie, "doe", "reindeer")
	updateString(trie, "dog", "puppy")
	updateString(trie, "dogglesworth", "cat")

	for i := 0; i < 2; i++ {
		res := getString(trie, "dog")
		if !bytes.Equal(res, []byte("puppy")) {
			t.Errorf("expected puppy got %x", res)
		}
		unknown := getString(trie, "unknown")
		if unknown != nil {
			t.Errorf("expected nil got %x", unknown)
		}
		if i == 1 {
			return
		}
		root, nodes := trie.Commit(false)
		db.Update(NewWithNodeSet(nodes))
		trie, _ = NewAccountTrie(TrieID(root), db)
	}
}

func TestDelete(t *testing.T) {
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	vals := []struct{ k, v string }{
		{"do", "verb"},
		{"ether", "wookiedoo"},
		{"horse", "stallion"},
		{"shaman", "horse"},
		{"doge", "coin"},
		{"ether", ""},
		{"dog", "puppy"},
		{"shaman", ""},
	}
	for _, val := range vals {
		if val.v != "" {
			updateString(trie, val.k, val.v)
		} else {
			deleteString(trie, val.k)
		}
	}

	hash := trie.Hash()
	exp := common.HexToHash("5991bb8c6514148a29db676a14ac506cd2cd5775ace63c30a4fe457715e9ac84")
	if hash != exp {
		t.Errorf("expected %x got %x", exp, hash)
	}
}

func TestEmptyValues(t *testing.T) {
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))

	vals := []struct{ k, v string }{
		{"do", "verb"},
		{"ether", "wookiedoo"},
		{"horse", "stallion"},
		{"shaman", "horse"},
		{"doge", "coin"},
		{"ether", ""},
		{"dog", "puppy"},
		{"shaman", ""},
	}
	for _, val := range vals {
		updateString(trie, val.k, val.v)
	}

	hash := trie.Hash()
	exp := common.HexToHash("5991bb8c6514148a29db676a14ac506cd2cd5775ace63c30a4fe457715e9ac84")
	if hash != exp {
		t.Errorf("expected %x got %x", exp, hash)
	}
}

func TestReplication(t *testing.T) {
	triedb := NewDatabase(rawdb.NewMemoryDatabase())
	trie := NewEmpty(triedb)
	vals := []struct{ k, v string }{
		{"do", "verb"},
		{"ether", "wookiedoo"},
		{"horse", "stallion"},
		{"shaman", "horse"},
		{"doge", "coin"},
		{"dog", "puppy"},
		{"somethingveryoddindeedthis is", "myothernodedata"},
	}
	for _, val := range vals {
		updateString(trie, val.k, val.v)
	}
	exp, nodes := trie.Commit(false)
	triedb.Update(NewWithNodeSet(nodes))

	// create a new trie on top of the database and check that lookups work.
	trie2, err := NewAccountTrie(TrieID(exp), triedb)
	if err != nil {
		t.Fatalf("can't recreate trie at %x: %v", exp, err)
	}
	for _, kv := range vals {
		if string(getString(trie2, kv.k)) != kv.v {
			t.Errorf("trie2 doesn't have %q => %q", kv.k, kv.v)
		}
	}
	hash, nodes := trie2.Commit(false)
	if hash != exp {
		t.Errorf("root failure. expected %x got %x", exp, hash)
	}

	// recreate the trie after commit
	if nodes != nil {
		triedb.Update(NewWithNodeSet(nodes))
	}
	trie2, err = NewAccountTrie(TrieID(hash), triedb)
	if err != nil {
		t.Fatalf("can't recreate trie at %x: %v", exp, err)
	}
	// perform some insertions on the new trie.
	vals2 := []struct{ k, v string }{
		{"do", "verb"},
		{"ether", "wookiedoo"},
		{"horse", "stallion"},
		// {"shaman", "horse"},
		// {"doge", "coin"},
		// {"ether", ""},
		// {"dog", "puppy"},
		// {"somethingveryoddindeedthis is", "myothernodedata"},
		// {"shaman", ""},
	}
	for _, val := range vals2 {
		updateString(trie2, val.k, val.v)
	}
	if hash := trie2.Hash(); hash != exp {
		t.Errorf("root failure. expected %x got %x", exp, hash)
	}
}

func TestLargeValue(t *testing.T) {
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	trie.Update([]byte("key1"), []byte{99, 99, 99, 99})
	trie.Update([]byte("key2"), bytes.Repeat([]byte{1}, 32))
	trie.Hash()
}

// TestRandomCases tests some cases that were found via random fuzzing
func TestRandomCases(t *testing.T) {
	var rt = []randTestStep{
		{op: 6, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 0
		{op: 6, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 1
		{op: 0, key: common.Hex2Bytes("d51b182b95d677e5f1c82508c0228de96b73092d78ce78b2230cd948674f66fd1483bd"), value: common.Hex2Bytes("0000000000000002")},           // step 2
		{op: 2, key: common.Hex2Bytes("c2a38512b83107d665c65235b0250002882ac2022eb00711552354832c5f1d030d0e408e"), value: common.Hex2Bytes("")},                         // step 3
		{op: 3, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 4
		{op: 3, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 5
		{op: 6, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 6
		{op: 3, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 7
		{op: 0, key: common.Hex2Bytes("c2a38512b83107d665c65235b0250002882ac2022eb00711552354832c5f1d030d0e408e"), value: common.Hex2Bytes("0000000000000008")},         // step 8
		{op: 0, key: common.Hex2Bytes("d51b182b95d677e5f1c82508c0228de96b73092d78ce78b2230cd948674f66fd1483bd"), value: common.Hex2Bytes("0000000000000009")},           // step 9
		{op: 2, key: common.Hex2Bytes("fd"), value: common.Hex2Bytes("")},                                                                                               // step 10
		{op: 6, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 11
		{op: 6, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 12
		{op: 0, key: common.Hex2Bytes("fd"), value: common.Hex2Bytes("000000000000000d")},                                                                               // step 13
		{op: 6, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 14
		{op: 1, key: common.Hex2Bytes("c2a38512b83107d665c65235b0250002882ac2022eb00711552354832c5f1d030d0e408e"), value: common.Hex2Bytes("")},                         // step 15
		{op: 3, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 16
		{op: 0, key: common.Hex2Bytes("c2a38512b83107d665c65235b0250002882ac2022eb00711552354832c5f1d030d0e408e"), value: common.Hex2Bytes("0000000000000011")},         // step 17
		{op: 5, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 18
		{op: 3, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 19
		{op: 0, key: common.Hex2Bytes("d51b182b95d677e5f1c82508c0228de96b73092d78ce78b2230cd948674f66fd1483bd"), value: common.Hex2Bytes("0000000000000014")},           // step 20
		{op: 0, key: common.Hex2Bytes("d51b182b95d677e5f1c82508c0228de96b73092d78ce78b2230cd948674f66fd1483bd"), value: common.Hex2Bytes("0000000000000015")},           // step 21
		{op: 0, key: common.Hex2Bytes("c2a38512b83107d665c65235b0250002882ac2022eb00711552354832c5f1d030d0e408e"), value: common.Hex2Bytes("0000000000000016")},         // step 22
		{op: 5, key: common.Hex2Bytes(""), value: common.Hex2Bytes("")},                                                                                                 // step 23
		{op: 1, key: common.Hex2Bytes("980c393656413a15c8da01978ed9f89feb80b502f58f2d640e3a2f5f7a99a7018f1b573befd92053ac6f78fca4a87268"), value: common.Hex2Bytes("")}, // step 24
		{op: 1, key: common.Hex2Bytes("fd"), value: common.Hex2Bytes("")},                                                                                               // step 25
	}
	runRandTest(rt)
}

// randTest performs random trie operations.
// Instances of this test are created by Generate.
type randTest []randTestStep

type randTestStep struct {
	op    int
	key   []byte // for opUpdate, opDelete, opGet
	value []byte // for opUpdate
	err   error  // for debugging
}

const (
	opUpdate = iota
	opDelete
	opGet
	opHash
	opCommit
	opItercheckhash
	opNodeDiff
	opProve
	opMax // boundary value, not an actual op
)

func (randTest) Generate(r *rand.Rand, size int) reflect.Value {
	var allKeys [][]byte
	genKey := func() []byte {
		if len(allKeys) < 2 || r.Intn(100) < 10 {
			// new key
			key := make([]byte, r.Intn(50))
			r.Read(key)
			allKeys = append(allKeys, key)
			return key
		}
		// use existing key
		return allKeys[r.Intn(len(allKeys))]
	}

	var steps randTest
	for i := 0; i < size; i++ {
		step := randTestStep{op: r.Intn(opMax)}
		switch step.op {
		case opUpdate:
			step.key = genKey()
			step.value = make([]byte, 8)
			binary.BigEndian.PutUint64(step.value, uint64(i))
		case opGet, opDelete, opProve:
			step.key = genKey()
		}
		steps = append(steps, step)
	}
	return reflect.ValueOf(steps)
}

func verifyAccessList(old *Trie, new *Trie, set *NodeSet) error {
	deletes, inserts, updates := diffTries(old, new)

	// Check insertion set
	for path := range inserts {
		n, ok := set.nodes[path]
		if !ok || n.isDeleted() {
			return errors.New("expect new node")
		}
		_, ok = set.accessList[path]
		if ok {
			return errors.New("unexpected origin value")
		}
	}
	// Check deletion set
	for path, blob := range deletes {
		n, ok := set.nodes[path]
		if !ok || !n.isDeleted() {
			return errors.New("expect deleted node")
		}
		v, ok := set.accessList[path]
		if !ok {
			return errors.New("expect origin value")
		}
		if !bytes.Equal(v, blob) {
			return errors.New("invalid origin value")
		}
	}
	// Check update set
	for path, blob := range updates {
		n, ok := set.nodes[path]
		if !ok || n.isDeleted() {
			return errors.New("expect updated node")
		}
		v, ok := set.accessList[path]
		if !ok {
			return errors.New("expect origin value")
		}
		if !bytes.Equal(v, blob) {
			return errors.New("invalid origin value")
		}
	}
	return nil
}

func runRandTest(rt randTest) bool {
	var (
		triedb   = NewDatabase(rawdb.NewMemoryDatabase())
		tr       = NewEmpty(triedb)
		values   = make(map[string]string) // tracks content of the trie
		origTrie = NewEmpty(triedb)
	)
	for i, step := range rt {
		// fmt.Printf("{op: %d, key: common.Hex2Bytes(\"%x\"), value: common.Hex2Bytes(\"%x\")}, // step %d\n",
		// 	step.op, step.key, step.value, i)

		switch step.op {
		case opUpdate:
			tr.Update(step.key, step.value)
			values[string(step.key)] = string(step.value)
		case opDelete:
			tr.Delete(step.key)
			delete(values, string(step.key))
		case opGet:
			v := tr.Get(step.key)
			want := values[string(step.key)]
			if string(v) != want {
				rt[i].err = fmt.Errorf("mismatch for key %#x, got %#x want %#x", step.key, v, want)
			}
		case opProve:
			hash := tr.Hash()
			if hash == types.EmptyRootHash {
				continue
			}
			proofDb := rawdb.NewMemoryDatabase()
			err := tr.Prove(step.key, 0, proofDb)
			if err != nil {
				rt[i].err = fmt.Errorf("failed for proving key %#x, %v", step.key, err)
			}
			_, err = VerifyProof(hash, step.key, proofDb)
			if err != nil {
				rt[i].err = fmt.Errorf("failed for verifying key %#x, %v", step.key, err)
			}
		case opHash:
			tr.Hash()
		case opCommit:
			root, nodes := tr.Commit(true)
			if nodes != nil {
				triedb.Update(NewWithNodeSet(nodes))
			}
			newtr, err := NewAccountTrie(TrieID(root), triedb)
			if err != nil {
				rt[i].err = err
				return false
			}
			if nodes != nil {
				if err := verifyAccessList(origTrie, newtr, nodes); err != nil {
					rt[i].err = err
					return false
				}
			}
			tr = newtr
			origTrie = tr.Copy()
		case opItercheckhash:
			checktr := NewEmpty(triedb)
			it := NewIterator(tr.NodeIterator(nil))
			for it.Next() {
				checktr.Update(it.Key, it.Value)
			}
			if tr.Hash() != checktr.Hash() {
				rt[i].err = fmt.Errorf("hash mismatch in opItercheckhash")
			}
		case opNodeDiff:
			var (
				origIter = origTrie.NodeIterator(nil)
				curIter  = tr.NodeIterator(nil)
				origSeen = make(map[string]struct{})
				curSeen  = make(map[string]struct{})
			)
			for origIter.Next(true) {
				if origIter.Leaf() {
					continue
				}
				origSeen[string(origIter.Path())] = struct{}{}
			}
			for curIter.Next(true) {
				if curIter.Leaf() {
					continue
				}
				curSeen[string(curIter.Path())] = struct{}{}
			}
			var (
				insertExp = make(map[string]struct{})
				deleteExp = make(map[string]struct{})
			)
			for path := range curSeen {
				_, present := origSeen[path]
				if !present {
					insertExp[path] = struct{}{}
				}
			}
			for path := range origSeen {
				_, present := curSeen[path]
				if !present {
					deleteExp[path] = struct{}{}
				}
			}
			if len(insertExp) != len(tr.tracer.inserts) {
				rt[i].err = fmt.Errorf("insert set mismatch")
			}
			if len(deleteExp) != len(tr.tracer.deletes) {
				rt[i].err = fmt.Errorf("delete set mismatch")
			}
			for insert := range tr.tracer.inserts {
				if _, present := insertExp[insert]; !present {
					rt[i].err = fmt.Errorf("missing inserted node")
				}
			}
			for del := range tr.tracer.deletes {
				if _, present := deleteExp[del]; !present {
					rt[i].err = fmt.Errorf("missing deleted node")
				}
			}
		}
		// Abort the test on error.
		if rt[i].err != nil {
			return false
		}
	}
	return true
}

func TestRandom(t *testing.T) {
	if err := quick.Check(runRandTest, nil); err != nil {
		if cerr, ok := err.(*quick.CheckError); ok {
			t.Fatalf("random test iteration %d failed: %s", cerr.Count, spew.Sdump(cerr.In))
		}
		t.Fatal(err)
	}
}

func TestTinyTrie(t *testing.T) {
	// Create a realistic account trie to hash
	_, accounts := makeAccounts(5)
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))

	type testCase struct {
		key, account []byte
		root         common.Hash
	}

	cases := []testCase{
		{
			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000001337"),
			accounts[3],
			common.HexToHash("8c6a85a4d9fda98feff88450299e574e5378e32391f75a055d470ac0653f1005"),
		}, {
			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000001338"),
			accounts[4],
			common.HexToHash("ec63b967e98a5720e7f720482151963982890d82c9093c0d486b7eb8883a66b1"),
		}, {
			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000001339"),
			accounts[4],
			common.HexToHash("0608c1d1dc3905fa22204c7a0e43644831c3b6d3def0f274be623a948197e64a"),
		},
	}
	for i, c := range cases {
		trie.Update(c.key, c.account)
		root := trie.Hash()
		if root != c.root {
			t.Errorf("case %d: got %x, exp %x", i, root, c.root)
		}
	}
	checktr := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	it := NewIterator(trie.NodeIterator(nil))
	for it.Next() {
		checktr.Update(it.Key, it.Value)
	}
	if troot, itroot := trie.Hash(), checktr.Hash(); troot != itroot {
		t.Fatalf("hash mismatch in opItercheckhash, trie: %x, check: %x", troot, itroot)
	}
}

func TestCommitAfterHash(t *testing.T) {
	// Create a realistic account trie to hash
	addresses, accounts := makeAccounts(1000)
	trie := NewEmpty(NewDatabase(rawdb.NewMemoryDatabase()))
	for i := 0; i < len(addresses); i++ {
		trie.Update(crypto.Keccak256(addresses[i][:]), accounts[i])
	}
	// Insert the accounts into the trie and hash it
	trie.Hash()
	trie.Commit(false)
	root := trie.Hash()
	exp := common.HexToHash("72f9d3f3fe1e1dd7b8936442e7642aef76371472d94319900790053c493f3fe6")
	if exp != root {
		t.Errorf("got %x, exp %x", root, exp)
	}
	root, _ = trie.Commit(false)
	if exp != root {
		t.Errorf("got %x, exp %x", root, exp)
	}
}

func makeAccounts(size int) (addresses [][20]byte, accounts [][]byte) {
	// Make the random benchmark deterministic
	random := rand.New(rand.NewSource(0))
	// Create a realistic account trie to hash
	addresses = make([][20]byte, size)
	for i := 0; i < len(addresses); i++ {
		data := make([]byte, 20)
		random.Read(data)
		copy(addresses[i][:], data)
	}
	accounts = make([][]byte, len(addresses))
	for i := 0; i < len(accounts); i++ {
		var (
			nonce = uint64(random.Int63())
			root  = types.EmptyRootHash
			code  = crypto.Keccak256(nil)
		)
		// The big.Rand function is not deterministic with regards to 64 vs 32 bit systems,
		// and will consume different amount of data from the rand source.
		//balance = new(big.Int).Rand(random, new(big.Int).Exp(common.Big2, common.Big256, nil))
		// Therefore, we instead just read via byte buffer
		numBytes := random.Uint32() % 33 // [0, 32] bytes
		balanceBytes := make([]byte, numBytes)
		random.Read(balanceBytes)
		balance := new(big.Int).SetBytes(balanceBytes)
		data, _ := rlp.EncodeToBytes(&types.StateAccount{Nonce: nonce, Balance: balance, Root: root, CodeHash: code})
		accounts[i] = data
	}
	return addresses, accounts
}

func getString(trie *Trie, k string) []byte {
	return trie.Get([]byte(k))
}

func updateString(trie *Trie, k, v string) {
	trie.Update([]byte(k), []byte(v))
}

func deleteString(trie *Trie, k string) {
	trie.Delete([]byte(k))
}

func TestDecodeNode(t *testing.T) {
	t.Parallel()

	var (
		hash  = make([]byte, 20)
		elems = make([]byte, 20)
	)
	for i := 0; i < 5000000; i++ {
		prng.Read(hash)
		prng.Read(elems)
		decodeNode(hash, elems)
	}
}