diff --git a/.travis.yml b/.travis.yml
index 638418c06c..9b86db97b6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,39 +13,80 @@ jobs:
 
   - stage: Lint
     sudo: false
-    go: '1.12.x'
+    go: '1.14.x'
     git:
       submodules: false
       script:
         - go run build/ci.go lint
 
-  - stage: Build and test
-    go: '1.12.x'
-    script:
-    - sudo modprobe fuse
-    - sudo chmod 666 /dev/fuse
-    - sudo chown root:$USER /etc/fuse.conf
-    - go run build/ci.go install
-    - while sleep 540; do echo "[ still running ]"; done &
-    - go run build/ci.go test -coverage
-    - kill %1
-    after_success:
-    - bash <(curl -s https://codecov.io/bash)
-
-  - go: '1.11.x'
-    script:
-    - sudo modprobe fuse
-    - sudo chmod 666 /dev/fuse
-    - sudo chown root:$USER /etc/fuse.conf
-    - go run build/ci.go install
-    - while sleep 540; do echo "[ still running ]"; done &
-    - go run build/ci.go test -coverage
-    - kill %1
-
+  - stage: Tests
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: A-B tests
+    script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/[a-b].*")
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/c[a-m].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: C-[a-m] tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/c[n-o].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: C-[n-o] tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/c[p-z].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: C-[p-z] tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/[d-i].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: D-I tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/[j-n].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: J-N tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/[o-r].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: O-R tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/s.*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: S tests
+  - script: travis_retry go run build/ci.go test -coverage $(go list ./... | grep "github.com\/XinFinOrg\/XDPoSChain\/[t-z].*")
+    os: linux
+    dist: bionic
+    go: 1.14.x
+    env:
+      - GO111MODULE=auto
+    name: T-Z tests
   - stage: Github release
-    go: '1.12.x'
+    go: '1.14.x'
     script:
-      - GOARCH=amd64 GOOS=linux go build -o ./build/bin/XDC-linux-amd64 -v ./cmd/XDC
+      - GOARCH=amd64 GOOS=linux go build -o ./build/bin/XDC-linux-amd64 ./cmd/XDC
     deploy:
       provider: releases
       api_key: $GITHUB_TOKEN
@@ -61,46 +102,46 @@ jobs:
       - docker
     install: skip
     before_script:
-      - docker build -t XDPoSChain/XDPoSChain .
-      - docker build -t XDPoSChain/node -f Dockerfile.node .
+      - docker build -t XinFinOrg/XDPoSChain .
+      - docker build -t XinFinOrg/node -f Dockerfile.node .
     script:
       - echo "$DOCKER_PASSWORD" | docker login --username "$DOCKER_USERNAME" --password-stdin
-      - docker tag XDPoSChain/XDPoSChain XDPoSChain/XDPoSChain:latest
-      - docker push XDPoSChain/XDPoSChain:latest
-      - docker tag XDPoSChain/XDPoSChain XDPoSChain/XDPoSChain:$TRAVIS_BUILD_ID
-      - docker push XDPoSChain/XDPoSChain:$TRAVIS_BUILD_ID
-      - docker tag XDPoSChain/node XDPoSChain/node:latest
-      - docker push XDPoSChain/node:latest
-      - docker tag XDPoSChain/node XDPoSChain/node:$TRAVIS_BUILD_ID
-      - docker push XDPoSChain/node:$TRAVIS_BUILD_ID
+      - docker tag XinFinOrg/XDPoSChain XinFinOrg/XDPoSChain:latest
+      - docker push XinFinOrg/XDPoSChain:latest
+      - docker tag XinFinOrg/XDPoSChain XinFinOrg/XDPoSChain:$TRAVIS_BUILD_ID
+      - docker push XinFinOrg/XDPoSChain:$TRAVIS_BUILD_ID
+      - docker tag XinFinOrg/node XinFinOrg/node:latest
+      - docker push XinFinOrg/node:latest
+      - docker tag XinFinOrg/node XinFinOrg/node:$TRAVIS_BUILD_ID
+      - docker push XinFinOrg/node:$TRAVIS_BUILD_ID
 
   - stage: Build and push image (tagged)
     services:
       - docker
     install: skip
     before_script:
-      - docker build -t XDPoSChain/XDPoSChain .
-      - docker build -t XDPoSChain/XDPoSChain -f Dockerfile.node .
+      - docker build -t XinFinOrg/XDPoSChain .
+      - docker build -t XinFinOrg/XDPoSChain -f Dockerfile.node .
     script:
       - echo "$DOCKER_PASSWORD" | docker login --username "$DOCKER_USERNAME" --password-stdin
-      - docker tag XDPoSChain/XDPoSChain XDPoSChain/XDPoSChain:latest
-      - docker push XDPoSChain/XDPoSChain:latest
-      - docker tag XDPoSChain/XDPoSChain XDPoSChain/XDPoSChain:$TRAVIS_TAG
-      - docker push XDPoSChain/XDPoSChain:$TRAVIS_TAG
-      - docker tag XDPoSChain/XDPoSChain XDPoSChain/node:latest
-      - docker push XDPoSChain/node:latest
-      - docker tag XDPoSChain/node XDPoSChain/node:$TRAVIS_TAG
-      - docker push XDPoSChain/node:$TRAVIS_TAG
+      - docker tag XinFinOrg/XDPoSChain XinFinOrg/XDPoSChain:latest
+      - docker push XinFinOrg/XDPoSChain:latest
+      - docker tag XinFinOrg/XDPoSChain XinFinOrg/XDPoSChain:$TRAVIS_TAG
+      - docker push XinFinOrg/XDPoSChain:$TRAVIS_TAG
+      - docker tag XinFinOrg/XDPoSChain XinFinOrg/node:latest
+      - docker push XinFinOrg/node:latest
+      - docker tag XinFinOrg/node XinFinOrg/node:$TRAVIS_TAG
+      - docker push XinFinOrg/node:$TRAVIS_TAG
 
 stages:
   - name: Lint
   - name: Build and test
   - name: Github release
-    if: type != pull_request AND branch =~ ^v AND tag IS present AND repo = XDPoSChain/XDPoSChain
+    if: type != pull_request AND branch =~ ^v AND tag IS present AND repo = XinFinOrg/XDPoSChain
   - name: Build and push image
-    if: type != pull_request AND branch = master AND tag IS blank AND repo = XDPoSChain/XDPoSChain
+    if: type != pull_request AND branch = master AND tag IS blank AND repo = XinFinOrg/XDPoSChain
   - name: Build and push image (tagged)
-    if: type != pull_request AND branch =~ ^v AND tag IS present AND repo = XDPoSChain/XDPoSChain
+    if: type != pull_request AND branch =~ ^v AND tag IS present AND repo = XinFinOrg/XDPoSChain
 
 notifications:
   slack:
diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index ca5972e32d..1f0f98e3b3 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -20,16 +20,18 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"github.com/XinFinOrg/XDPoSChain/consensus"
-	"github.com/XinFinOrg/XDPoSChain/core/rawdb"
 	"math/big"
 	"sync"
 	"time"
 
+	"github.com/XinFinOrg/XDPoSChain/consensus"
+	"github.com/XinFinOrg/XDPoSChain/core/rawdb"
+
 	"github.com/XinFinOrg/XDPoSChain"
 	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
 	"github.com/XinFinOrg/XDPoSChain/common"
 	"github.com/XinFinOrg/XDPoSChain/common/math"
+	"github.com/XinFinOrg/XDPoSChain/consensus/XDPoS"
 	"github.com/XinFinOrg/XDPoSChain/consensus/ethash"
 	"github.com/XinFinOrg/XDPoSChain/core"
 	"github.com/XinFinOrg/XDPoSChain/core/bloombits"
@@ -64,6 +66,31 @@ type SimulatedBackend struct {
 	config *params.ChainConfig
 }
 
+// XDC simulated backend for testing purpose.
+func NewXDCSimulatedBackend(alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
+	// database := ethdb.NewMemDatabase()
+	database := rawdb.NewMemoryDatabase()
+
+	genesis := core.Genesis{
+		GasLimit:  gasLimit, // need this big, support initial smart contract
+		Config:    params.TestXDPoSMockChainConfig,
+		Alloc:     alloc,
+		ExtraData: append(make([]byte, 32), make([]byte, 65)...),
+	}
+	genesis.MustCommit(database)
+	blockchain, _ := core.NewBlockChain(database, nil, genesis.Config, XDPoS.NewFaker(database), vm.Config{})
+
+	backend := &SimulatedBackend{
+		database:   database,
+		blockchain: blockchain,
+		config:     genesis.Config,
+		events:     filters.NewEventSystem(new(event.TypeMux), &filterBackend{database, blockchain}, false),
+	}
+	blockchain.Client = backend
+	backend.rollback()
+	return backend
+}
+
 // NewSimulatedBackend creates a new binding backend using a simulated blockchain
 // for testing purposes.
 func NewSimulatedBackend(alloc core.GenesisAlloc) *SimulatedBackend {
@@ -103,7 +130,7 @@ func (b *SimulatedBackend) Rollback() {
 }
 
 func (b *SimulatedBackend) rollback() {
-	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(int, *core.BlockGen) {})
+	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), b.blockchain.Engine(), b.database, 1, func(int, *core.BlockGen) {})
 	statedb, _ := b.blockchain.State()
 
 	b.pendingBlock = blocks[0]
@@ -359,7 +386,8 @@ func (b *SimulatedBackend) SendTransaction(ctx context.Context, tx *types.Transa
 		panic(fmt.Errorf("invalid transaction nonce: got %d, want %d", tx.Nonce(), nonce))
 	}
 
-	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(number int, block *core.BlockGen) {
+	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), b.blockchain.Engine(), b.database, 1, func(number int, block *core.BlockGen) {
+		// blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), b.blockchain.Engine(), b.database, 1, func(number int, block *core.BlockGen) {
 		for _, tx := range b.pendingBlock.Transactions() {
 			block.AddTxWithChain(b.blockchain, tx)
 		}
@@ -438,7 +466,8 @@ func (b *SimulatedBackend) SubscribeFilterLogs(ctx context.Context, query XDPoSC
 func (b *SimulatedBackend) AdjustTime(adjustment time.Duration) error {
 	b.mu.Lock()
 	defer b.mu.Unlock()
-	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(number int, block *core.BlockGen) {
+	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), b.blockchain.Engine(), b.database, 1, func(number int, block *core.BlockGen) {
+		// blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), b.blockchain.Engine(), b.database, 1, func(number int, block *core.BlockGen) {
 		for _, tx := range b.pendingBlock.Transactions() {
 			block.AddTx(tx)
 		}
@@ -452,6 +481,10 @@ func (b *SimulatedBackend) AdjustTime(adjustment time.Duration) error {
 	return nil
 }
 
+func (b *SimulatedBackend) GetBlockChain() *core.BlockChain {
+	return b.blockchain
+}
+
 // callmsg implements core.Message to allow passing it as a transaction simulator.
 type callmsg struct {
 	XDPoSChain.CallMsg
diff --git a/accounts/abi/bind/bind_test.go b/accounts/abi/bind/bind_test.go
index 242cea0ef6..858a2a0cc9 100644
--- a/accounts/abi/bind/bind_test.go
+++ b/accounts/abi/bind/bind_test.go
@@ -229,7 +229,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy an interaction tester contract and call a transaction on it
 			_, _, interactor, err := DeployInteractor(auth, sim, "Deploy string")
@@ -270,7 +270,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a tuple tester contract and execute a structured call on it
 			_, _, getter, err := DeployGetter(auth, sim)
@@ -302,7 +302,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a tuple tester contract and execute a structured call on it
 			_, _, tupler, err := DeployTupler(auth, sim)
@@ -344,7 +344,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a slice tester contract and execute a n array call on it
 			_, _, slicer, err := DeploySlicer(auth, sim)
@@ -378,7 +378,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a default method invoker contract and execute its default method
 			_, _, defaulter, err := DeployDefaulter(auth, sim)
@@ -411,7 +411,7 @@ var bindTests = []struct {
 		`[{"constant":true,"inputs":[],"name":"String","outputs":[{"name":"","type":"string"}],"type":"function"}]`,
 		`
 			// Create a simulator and wrap a non-deployed contract
-			sim := backends.NewSimulatedBackend(nil)
+			sim := backends.NewXDCSimulatedBackend(nil, uint64(10000000000))
 
 			nonexistent, err := NewNonExistent(common.Address{}, sim)
 			if err != nil {
@@ -447,7 +447,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a funky gas pattern contract
 			_, _, limiter, err := DeployFunkyGasPattern(auth, sim)
@@ -482,7 +482,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a sender tester contract and execute a structured call on it
 			_, _, callfrom, err := DeployCallFrom(auth, sim)
@@ -542,7 +542,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a underscorer tester contract and execute a structured call on it
 			_, _, underscorer, err := DeployUnderscorer(auth, sim)
@@ -612,7 +612,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy an eventer contract
 			_, _, eventer, err := DeployEventer(auth, sim)
@@ -761,7 +761,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}})
+			sim := backends.NewXDCSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			//deploy the test contract
 			_, _, testContract, err := DeployDeeplyNestedArray(auth, sim)
diff --git a/accounts/abi/bind/util_test.go b/accounts/abi/bind/util_test.go
index a983f02e00..306fc7b3ca 100644
--- a/accounts/abi/bind/util_test.go
+++ b/accounts/abi/bind/util_test.go
@@ -53,9 +53,11 @@ var waitDeployedTests = map[string]struct {
 
 func TestWaitDeployed(t *testing.T) {
 	for name, test := range waitDeployedTests {
-		backend := backends.NewSimulatedBackend(core.GenesisAlloc{
-			crypto.PubkeyToAddress(testKey.PublicKey): {Balance: big.NewInt(10000000000)},
-		})
+		backend := backends.NewXDCSimulatedBackend(
+			core.GenesisAlloc{
+				crypto.PubkeyToAddress(testKey.PublicKey): {Balance: big.NewInt(10000000000)},
+			}, 10000000,
+		)
 
 		// Create the transaction.
 		tx := types.NewContractCreation(0, big.NewInt(0), test.gas, big.NewInt(1), common.FromHex(test.code))
diff --git a/accounts/keystore/testdata/keystore/README b/accounts/keystore/testdata/keystore/README
index a5a86f964d..c489123c26 100644
--- a/accounts/keystore/testdata/keystore/README
+++ b/accounts/keystore/testdata/keystore/README
@@ -4,11 +4,11 @@ The passphrase that unlocks them is "foobar".
 The "good" key files which are supposed to be loadable are:
 
 - File: UTC--2016-03-22T12-57-55.920751759Z--7ef5a6135f1fd6a02593eedc869c6d41d934aef8
-  Address: 0x7ef5a6135f1fd6a02593eedc869c6d41d934aef8
+  Address: xdc7ef5a6135f1fd6a02593eedc869c6d41d934aef8
 - File: aaa
-  Address: 0xf466859ead1932d743d622cb74fc058882e8648a
+  Address: xdcf466859ead1932d743d622cb74fc058882e8648a
 - File: zzz
-  Address: 0x289d485d9771714cce91d3393d764e1311907acc
+  Address: xdc289d485d9771714cce91d3393d764e1311907acc
 
 The other files (including this README) are broken in various ways
 and should not be picked up by package accounts:
diff --git a/cmd/XDC/accountcmd_test.go b/cmd/XDC/accountcmd_test.go
index 78f0ab3321..04553b1356 100644
--- a/cmd/XDC/accountcmd_test.go
+++ b/cmd/XDC/accountcmd_test.go
@@ -75,7 +75,7 @@ Your new account is locked with a password. Please give a password. Do not forge
 Passphrase: {{.InputLine "foobar"}}
 Repeat passphrase: {{.InputLine "foobar"}}
 `)
-	XDC.ExpectRegexp(`Address: \{[0-9a-f]{40}\}\n`)
+	XDC.ExpectRegexp(`Address: \{xdc[0-9a-f]{40}\}\n`)
 }
 
 func TestAccountNewBadRepeat(t *testing.T) {
@@ -112,7 +112,7 @@ func TestWalletImport(t *testing.T) {
 	XDC.Expect(`
 !! Unsupported terminal, password will be echoed.
 Passphrase: {{.InputLine "foo"}}
-Address: {d4584b5f6229b7be90727b0fc8c6b91bb427821f}
+Address: {xdcd4584b5f6229b7be90727b0fc8c6b91bb427821f}
 `)
 
 	files, err := ioutil.ReadDir(filepath.Join(XDC.Datadir, "keystore"))
@@ -146,7 +146,7 @@ Passphrase: {{.InputLine "foobar"}}
 
 	wantMessages := []string{
 		"Unlocked account",
-		"=0xf466859eAD1932D743d622CB74FC058882E8648A",
+		"=xdcf466859eAD1932D743d622CB74FC058882E8648A",
 	}
 	for _, m := range wantMessages {
 		if !strings.Contains(XDC.StderrText(), m) {
@@ -191,8 +191,8 @@ Passphrase: {{.InputLine "foobar"}}
 
 	wantMessages := []string{
 		"Unlocked account",
-		"=0x7EF5A6135f1FD6a02593eEdC869c6D41D934aef8",
-		"=0x289d485D9771714CCe91D3393D764E1311907ACc",
+		"=xdc7EF5A6135f1FD6a02593eEdC869c6D41D934aef8",
+		"=xdc289d485D9771714CCe91D3393D764E1311907ACc",
 	}
 	for _, m := range wantMessages {
 		if !strings.Contains(XDC.StderrText(), m) {
@@ -211,8 +211,8 @@ func TestUnlockFlagPasswordFile(t *testing.T) {
 
 	wantMessages := []string{
 		"Unlocked account",
-		"=0x7EF5A6135f1FD6a02593eEdC869c6D41D934aef8",
-		"=0x289d485D9771714CCe91D3393D764E1311907ACc",
+		"=xdc7EF5A6135f1FD6a02593eEdC869c6D41D934aef8",
+		"=xdc289d485D9771714CCe91D3393D764E1311907ACc",
 	}
 	for _, m := range wantMessages {
 		if !strings.Contains(XDC.StderrText(), m) {
@@ -261,7 +261,7 @@ In order to avoid this warning, you need to remove the following duplicate key f
 
 	wantMessages := []string{
 		"Unlocked account",
-		"=0xf466859eAD1932D743d622CB74FC058882E8648A",
+		"=xdcf466859eAD1932D743d622CB74FC058882E8648A",
 	}
 	for _, m := range wantMessages {
 		if !strings.Contains(XDC.StderrText(), m) {
diff --git a/cmd/XDC/consolecmd_test.go b/cmd/XDC/consolecmd_test.go
index 879577df0f..2801583ce2 100644
--- a/cmd/XDC/consolecmd_test.go
+++ b/cmd/XDC/consolecmd_test.go
@@ -31,14 +31,14 @@ import (
 )
 
 const (
-	ipcAPIs  = "admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 XDPoS:1.0 rpc:1.0 XDCx:1.0 XDCxlending:1.0 txpool:1.0 web3:1.0"
+	ipcAPIs  = "XDCx:1.0 XDCxlending:1.0 XDPoS:1.0 admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0"
 	httpAPIs = "eth:1.0 net:1.0 rpc:1.0 web3:1.0"
 )
 
 // Tests that a node embedded within a console can be started up properly and
 // then terminated by closing the input stream.
 func TestConsoleWelcome(t *testing.T) {
-	coinbase := "0x8605cdbbdb6d264aa742e77020dcbc58fcdce182"
+	coinbase := "xdc8605cdbbdb6d264aa742e77020dcbc58fcdce182"
 
 	// Start a XDC console, make sure it's cleaned up and terminate the console
 	XDC := runXDC(t,
@@ -73,7 +73,7 @@ at block: 0 ({{niltime}})
 // Tests that a console can be attached to a running node via various means.
 func TestIPCAttachWelcome(t *testing.T) {
 	// Configure the instance for IPC attachement
-	coinbase := "0x8605cdbbdb6d264aa742e77020dcbc58fcdce182"
+	coinbase := "xdc8605cdbbdb6d264aa742e77020dcbc58fcdce182"
 	var ipc string
 	if runtime.GOOS == "windows" {
 		ipc = `\\.\pipe\XDC` + strconv.Itoa(trulyRandInt(100000, 999999))
@@ -95,7 +95,7 @@ func TestIPCAttachWelcome(t *testing.T) {
 }
 
 func TestHTTPAttachWelcome(t *testing.T) {
-	coinbase := "0x8605cdbbdb6d264aa742e77020dcbc58fcdce182"
+	coinbase := "xdc8605cdbbdb6d264aa742e77020dcbc58fcdce182"
 	port := strconv.Itoa(trulyRandInt(1024, 65536)) // Yeah, sometimes this will fail, sorry :P
 	XDC := runXDC(t,
 		"--XDCx.datadir", tmpdir(t)+"XDCx/"+time.Now().String(),
@@ -110,7 +110,7 @@ func TestHTTPAttachWelcome(t *testing.T) {
 }
 
 func TestWSAttachWelcome(t *testing.T) {
-	coinbase := "0x8605cdbbdb6d264aa742e77020dcbc58fcdce182"
+	coinbase := "xdc8605cdbbdb6d264aa742e77020dcbc58fcdce182"
 	port := strconv.Itoa(trulyRandInt(1024, 65536)) // Yeah, sometimes this will fail, sorry :P
 
 	XDC := runXDC(t,
diff --git a/cmd/ethkey/message_test.go b/cmd/ethkey/message_test.go
index 39352b1d22..e8e3806654 100644
--- a/cmd/ethkey/message_test.go
+++ b/cmd/ethkey/message_test.go
@@ -40,7 +40,7 @@ func TestMessageSignVerify(t *testing.T) {
 Passphrase: {{.InputLine "foobar"}}
 Repeat passphrase: {{.InputLine "foobar"}}
 `)
-	_, matches := generate.ExpectRegexp(`Address: (0x[0-9a-fA-F]{40})\n`)
+	_, matches := generate.ExpectRegexp(`Address: (xdc[0-9a-fA-F]{40})\n`)
 	address := matches[1]
 	generate.ExpectExit()
 
@@ -59,7 +59,7 @@ Passphrase: {{.InputLine "foobar"}}
 	_, matches = verify.ExpectRegexp(`
 Signature verification successful!
 Recovered public key: [0-9a-f]+
-Recovered address: (0x[0-9a-fA-F]{40})
+Recovered address: (xdc[0-9a-fA-F]{40})
 `)
 	recovered := matches[1]
 	verify.ExpectExit()
diff --git a/cmd/puppeth/wizard_genesis.go b/cmd/puppeth/wizard_genesis.go
index 9c036c9873..2a04ba5946 100644
--- a/cmd/puppeth/wizard_genesis.go
+++ b/cmd/puppeth/wizard_genesis.go
@@ -177,7 +177,7 @@ func (w *wizard) makeGenesis() {
 		// Validator Smart Contract Code
 		pKey, _ := crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
 		addr := crypto.PubkeyToAddress(pKey.PublicKey)
-		contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}})
+		contractBackend := backends.NewXDCSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}}, 10000000)
 		transactOpts := bind.NewKeyedTransactor(pKey)
 
 		validatorAddress, _, err := validatorContract.DeployValidator(transactOpts, contractBackend, signers, validatorCaps, owner)
diff --git a/common/types.go b/common/types.go
index 7e0b5f2587..4c31429a53 100644
--- a/common/types.go
+++ b/common/types.go
@@ -167,9 +167,16 @@ func BytesToAddress(b []byte) Address {
 	a.SetBytes(b)
 	return a
 }
+
 func StringToAddress(s string) Address { return BytesToAddress([]byte(s)) }
-func BigToAddress(b *big.Int) Address  { return BytesToAddress(b.Bytes()) }
-func HexToAddress(s string) Address    { return BytesToAddress(FromHex(s)) }
+
+// BigToAddress returns Address with byte values of b.
+// If b is larger than len(h), b will be cropped from the left.
+func BigToAddress(b *big.Int) Address { return BytesToAddress(b.Bytes()) }
+
+// HexToAddress returns Address with byte values of s.
+// If s is larger than len(h), s will be cropped from the left.
+func HexToAddress(s string) Address { return BytesToAddress(FromHex(s)) }
 
 // IsHexAddress verifies whether a string can represent a valid hex-encoded
 // Ethereum address or not.
diff --git a/consensus/XDPoS/XDPoS.go b/consensus/XDPoS/XDPoS.go
index b54902a6a1..d4b19bba84 100644
--- a/consensus/XDPoS/XDPoS.go
+++ b/consensus/XDPoS/XDPoS.go
@@ -297,6 +297,32 @@ func New(config *params.XDPoSConfig, db ethdb.Database) *XDPoS {
 	}
 }
 
+// NewFullFaker creates an ethash consensus engine with a full fake scheme that
+// accepts all blocks as valid, without checking any consensus rules whatsoever.
+func NewFaker(db ethdb.Database) *XDPoS {
+	var fakeEngine *XDPoS
+	// Set any missing consensus parameters to their defaults
+	conf := params.TestXDPoSMockChainConfig.XDPoS
+
+	// Allocate the snapshot caches and create the engine
+	BlockSigners, _ := lru.New(blockSignersCacheLimit)
+	recents, _ := lru.NewARC(inmemorySnapshots)
+	signatures, _ := lru.NewARC(inmemorySnapshots)
+	validatorSignatures, _ := lru.NewARC(inmemorySnapshots)
+	verifiedHeaders, _ := lru.NewARC(inmemorySnapshots)
+	fakeEngine = &XDPoS{
+		config:              conf,
+		db:                  db,
+		BlockSigners:        BlockSigners,
+		recents:             recents,
+		signatures:          signatures,
+		verifiedHeaders:     verifiedHeaders,
+		validatorSignatures: validatorSignatures,
+		proposals:           make(map[common.Address]bool),
+	}
+	return fakeEngine
+}
+
 // Author implements consensus.Engine, returning the Ethereum address recovered
 // from the signature in the header's extra-data section.
 func (c *XDPoS) Author(header *types.Header) (common.Address, error) {
@@ -349,6 +375,10 @@ func (c *XDPoS) verifyHeaderWithCache(chain consensus.ChainReader, header *types
 // looking those up from the database. This is useful for concurrently verifying
 // a batch of new headers.
 func (c *XDPoS) verifyHeader(chain consensus.ChainReader, header *types.Header, parents []*types.Header, fullVerify bool) error {
+	// If we're running a engine faking, accept any block as valid
+	if c.config.SkipValidation {
+		return nil
+	}
 	if common.IsTestnet {
 		fullVerify = false
 	}
@@ -1084,6 +1114,10 @@ func (c *XDPoS) CalcDifficulty(chain consensus.ChainReader, time uint64, parent
 }
 
 func (c *XDPoS) calcDifficulty(chain consensus.ChainReader, parent *types.Header, signer common.Address) *big.Int {
+	// If we're running a engine faking, skip calculation
+	if c.config.SkipValidation {
+		return big.NewInt(1)
+	}
 	len, preIndex, curIndex, _, err := c.YourTurn(chain, parent, signer)
 	if err != nil {
 		return big.NewInt(int64(len + curIndex - preIndex))
diff --git a/contracts/blocksigner/blocksigner_test.go b/contracts/blocksigner/blocksigner_test.go
index 0a649ea2f6..e3e0854d24 100644
--- a/contracts/blocksigner/blocksigner_test.go
+++ b/contracts/blocksigner/blocksigner_test.go
@@ -21,12 +21,13 @@ import (
 	"testing"
 	"time"
 
+	"math/rand"
+
 	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
 	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind/backends"
 	"github.com/XinFinOrg/XDPoSChain/common"
 	"github.com/XinFinOrg/XDPoSChain/core"
 	"github.com/XinFinOrg/XDPoSChain/crypto"
-	"math/rand"
 )
 
 var (
@@ -35,7 +36,7 @@ var (
 )
 
 func TestBlockSigner(t *testing.T) {
-	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}})
+	contractBackend := backends.NewXDCSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}}, 10000000)
 	transactOpts := bind.NewKeyedTransactor(key)
 
 	blockSignerAddress, blockSigner, err := DeployBlockSigner(transactOpts, contractBackend, big.NewInt(99))
diff --git a/contracts/chequebook/cheque_test.go b/contracts/chequebook/cheque_test.go
index dbf28f69e1..17b3237506 100644
--- a/contracts/chequebook/cheque_test.go
+++ b/contracts/chequebook/cheque_test.go
@@ -42,7 +42,7 @@ var (
 )
 
 func newTestBackend() *backends.SimulatedBackend {
-	return backends.NewSimulatedBackend(core.GenesisAlloc{
+	return backends.NewXDCSimulatedBackend(core.GenesisAlloc{
 		addr0: {Balance: big.NewInt(1000000000)},
 		addr1: {Balance: big.NewInt(1000000000)},
 		addr2: {Balance: big.NewInt(1000000000)},
diff --git a/contracts/ens/ens_test.go b/contracts/ens/ens_test.go
index 6b6facbccc..2705c75198 100644
--- a/contracts/ens/ens_test.go
+++ b/contracts/ens/ens_test.go
@@ -35,7 +35,7 @@ var (
 )
 
 func TestENS(t *testing.T) {
-	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}})
+	contractBackend := backends.NewXDCSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}}, 10000000)
 	transactOpts := bind.NewKeyedTransactor(key)
 
 	ensAddr, ens, err := DeployENS(transactOpts, contractBackend)
diff --git a/contracts/randomize/randomize_test.go b/contracts/randomize/randomize_test.go
index 063b2832b6..bc35b86309 100644
--- a/contracts/randomize/randomize_test.go
+++ b/contracts/randomize/randomize_test.go
@@ -40,7 +40,7 @@ var (
 )
 
 func TestRandomize(t *testing.T) {
-	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(100000000000000)}})
+	contractBackend := backends.NewXDCSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(100000000000000)}}, 10000000)
 	transactOpts := bind.NewKeyedTransactor(key)
 	transactOpts.GasLimit = 1000000
 
diff --git a/contracts/utils_test.go b/contracts/utils_test.go
index abcf84aeb3..d267eda83e 100644
--- a/contracts/utils_test.go
+++ b/contracts/utils_test.go
@@ -19,6 +19,11 @@ import (
 	"bytes"
 	"context"
 	"crypto/ecdsa"
+	"math/big"
+	"math/rand"
+	"testing"
+	"time"
+
 	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
 	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind/backends"
 	"github.com/XinFinOrg/XDPoSChain/common"
@@ -27,10 +32,6 @@ import (
 	"github.com/XinFinOrg/XDPoSChain/core"
 	"github.com/XinFinOrg/XDPoSChain/core/types"
 	"github.com/XinFinOrg/XDPoSChain/crypto"
-	"math/big"
-	"math/rand"
-	"testing"
-	"time"
 )
 
 var (
@@ -46,7 +47,7 @@ var (
 
 func getCommonBackend() *backends.SimulatedBackend {
 	genesis := core.GenesisAlloc{acc1Addr: {Balance: big.NewInt(1000000000000)}}
-	backend := backends.NewSimulatedBackend(genesis)
+	backend := backends.NewXDCSimulatedBackend(genesis, 10000000)
 	backend.Commit()
 
 	return backend
diff --git a/contracts/validator/validator_test.go b/contracts/validator/validator_test.go
index 7cb3641bb9..a3a9b3cbc9 100644
--- a/contracts/validator/validator_test.go
+++ b/contracts/validator/validator_test.go
@@ -46,7 +46,7 @@ var (
 )
 
 func TestValidator(t *testing.T) {
-	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}})
+	contractBackend := backends.NewXDCSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}}, 10000000)
 	transactOpts := bind.NewKeyedTransactor(key)
 
 	validatorCap := new(big.Int)
@@ -82,7 +82,7 @@ func TestValidator(t *testing.T) {
 }
 
 func TestRewardBalance(t *testing.T) {
-	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{
+	contractBackend := backends.NewXDCSimulatedBackend(core.GenesisAlloc{
 		acc1Addr: {Balance: new(big.Int).SetUint64(10000000)},
 		acc2Addr: {Balance: new(big.Int).SetUint64(10000000)},
 		acc4Addr: {Balance: new(big.Int).SetUint64(10000000)},
diff --git a/core/blockchain.go b/core/blockchain.go
index 1ccb46c13d..cf9bb23a28 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -152,10 +152,10 @@ type BlockChain struct {
 	validator Validator // block and state validator interface
 	vmConfig  vm.Config
 
-	badBlocks   *lru.Cache // Bad block cache
-	IPCEndpoint string
-	Client      *ethclient.Client // Global ipc client instance.
-
+	badBlocks      *lru.Cache              // Bad block cache
+	shouldPreserve func(*types.Block) bool // Function used to determine whether should preserve the given block.
+	IPCEndpoint    string
+	Client         bind.ContractBackend // Global ipc client instance.
 	// Blocks hash array by block number
 	// cache field for tracking finality purpose, can't use for tracking block vs block relationship
 	blocksHashCache *lru.Cache
@@ -1362,6 +1362,13 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 	// Set new head.
 	if status == CanonStatTy {
 		bc.insert(block)
+		// prepare set of masternodes for the next epoch
+		if bc.chainConfig.XDPoS != nil && ((block.NumberU64() % bc.chainConfig.XDPoS.Epoch) == (bc.chainConfig.XDPoS.Epoch - bc.chainConfig.XDPoS.Gap)) {
+			err := bc.UpdateM1()
+			if err != nil {
+				log.Crit("Error when update masternodes set. Stopping node", "err", err)
+			}
+		}
 	}
 	// save cache BlockSigners
 	if bc.chainConfig.XDPoS != nil && bc.chainConfig.IsTIPSigning(block.Number()) {
@@ -1695,13 +1702,6 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 				CheckpointCh <- 1
 
 			}
-			// prepare set of masternodes for the next epoch
-			if (chain[i].NumberU64() % bc.chainConfig.XDPoS.Epoch) == (bc.chainConfig.XDPoS.Epoch - bc.chainConfig.XDPoS.Gap) {
-				err := bc.UpdateM1()
-				if err != nil {
-					log.Crit("Error when update masternodes set. Stopping node", "err", err)
-				}
-			}
 		}
 	}
 	// Append a single chain head event if we've progressed the chain
@@ -2039,14 +2039,6 @@ func (bc *BlockChain) insertBlock(block *types.Block) ([]interface{}, []*types.L
 			CheckpointCh <- 1
 
 		}
-		// prepare set of masternodes for the next epoch
-		if (block.NumberU64() % bc.chainConfig.XDPoS.Epoch) == (bc.chainConfig.XDPoS.Epoch - bc.chainConfig.XDPoS.Gap) {
-			err := bc.UpdateM1()
-			if err != nil {
-				log.Error("Error when update masternodes set. Stopping node", "err", err)
-				os.Exit(1)
-			}
-		}
 	}
 	// Append a single chain head event if we've progressed the chain
 	if status == CanonStatTy && bc.CurrentBlock().Hash() == block.Hash() {
@@ -2193,6 +2185,13 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Block) error {
 			return err
 		}
 		addedTxs = append(addedTxs, newChain[i].Transactions()...)
+		// prepare set of masternodes for the next epoch
+		if bc.chainConfig.XDPoS != nil && ((newChain[i].NumberU64() % bc.chainConfig.XDPoS.Epoch) == (bc.chainConfig.XDPoS.Epoch - bc.chainConfig.XDPoS.Gap)) {
+			err := bc.UpdateM1()
+			if err != nil {
+				log.Crit("Error when update masternodes set. Stopping node", "err", err)
+			}
+		}
 	}
 	// calculate the difference between deleted and added transactions
 	diff := types.TxDifference(deletedTxs, addedTxs)
@@ -2428,7 +2427,7 @@ func (bc *BlockChain) SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscript
 }
 
 // Get current IPC Client.
-func (bc *BlockChain) GetClient() (*ethclient.Client, error) {
+func (bc *BlockChain) GetClient() (bind.ContractBackend, error) {
 	if bc.Client == nil {
 		// Inject ipc client global instance.
 		client, err := ethclient.Dial(bc.IPCEndpoint)
diff --git a/eth/api_backend.go b/eth/api_backend.go
index f6bad9ead8..cb249b67ab 100644
--- a/eth/api_backend.go
+++ b/eth/api_backend.go
@@ -27,6 +27,7 @@ import (
 
 	"github.com/XinFinOrg/XDPoSChain/XDCx/tradingstate"
 	"github.com/XinFinOrg/XDPoSChain/XDCxlending"
+	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
 
 	"github.com/XinFinOrg/XDPoSChain/XDCx"
 
@@ -45,7 +46,6 @@ import (
 	"github.com/XinFinOrg/XDPoSChain/core/vm"
 	"github.com/XinFinOrg/XDPoSChain/eth/downloader"
 	"github.com/XinFinOrg/XDPoSChain/eth/gasprice"
-	"github.com/XinFinOrg/XDPoSChain/ethclient"
 	"github.com/XinFinOrg/XDPoSChain/ethdb"
 	"github.com/XinFinOrg/XDPoSChain/event"
 	"github.com/XinFinOrg/XDPoSChain/log"
@@ -253,7 +253,8 @@ func (b *EthApiBackend) ServiceFilter(ctx context.Context, session *bloombits.Ma
 	}
 }
 
-func (b *EthApiBackend) GetIPCClient() (*ethclient.Client, error) {
+func (b *EthApiBackend) GetIPCClient() (bind.ContractBackend, error) {
+	// func (b *EthApiBackend) GetIPCClient() (*ethclient.Client, error) {
 	client, err := b.eth.blockchain.GetClient()
 	if err != nil {
 		return nil, err
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index 63ad4a095d..7f2d297baf 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -19,9 +19,11 @@ package ethapi
 
 import (
 	"context"
+	"math/big"
+
 	"github.com/XinFinOrg/XDPoSChain/XDCx/tradingstate"
 	"github.com/XinFinOrg/XDPoSChain/XDCxlending"
-	"math/big"
+	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
 
 	"github.com/XinFinOrg/XDPoSChain/XDCx"
 
@@ -33,7 +35,6 @@ import (
 	"github.com/XinFinOrg/XDPoSChain/core/types"
 	"github.com/XinFinOrg/XDPoSChain/core/vm"
 	"github.com/XinFinOrg/XDPoSChain/eth/downloader"
-	"github.com/XinFinOrg/XDPoSChain/ethclient"
 	"github.com/XinFinOrg/XDPoSChain/ethdb"
 	"github.com/XinFinOrg/XDPoSChain/event"
 	"github.com/XinFinOrg/XDPoSChain/params"
@@ -83,7 +84,7 @@ type Backend interface {
 
 	ChainConfig() *params.ChainConfig
 	CurrentBlock() *types.Block
-	GetIPCClient() (*ethclient.Client, error)
+	GetIPCClient() (bind.ContractBackend, error)
 	GetEngine() consensus.Engine
 	GetRewardByHash(hash common.Hash) map[string]map[string]map[string]*big.Int
 
diff --git a/les/api_backend.go b/les/api_backend.go
index 84192196bb..d7909b81da 100644
--- a/les/api_backend.go
+++ b/les/api_backend.go
@@ -20,12 +20,14 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
-	"github.com/XinFinOrg/XDPoSChain/XDCx/tradingstate"
-	"github.com/XinFinOrg/XDPoSChain/XDCxlending"
 	"io/ioutil"
 	"math/big"
 	"path/filepath"
 
+	"github.com/XinFinOrg/XDPoSChain/XDCx/tradingstate"
+	"github.com/XinFinOrg/XDPoSChain/XDCxlending"
+	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
+
 	"github.com/XinFinOrg/XDPoSChain/XDCx"
 
 	"github.com/XinFinOrg/XDPoSChain/accounts"
@@ -39,7 +41,6 @@ import (
 	"github.com/XinFinOrg/XDPoSChain/core/vm"
 	"github.com/XinFinOrg/XDPoSChain/eth/downloader"
 	"github.com/XinFinOrg/XDPoSChain/eth/gasprice"
-	"github.com/XinFinOrg/XDPoSChain/ethclient"
 	"github.com/XinFinOrg/XDPoSChain/ethdb"
 	"github.com/XinFinOrg/XDPoSChain/event"
 	"github.com/XinFinOrg/XDPoSChain/light"
@@ -214,7 +215,9 @@ func (b *LesApiBackend) ServiceFilter(ctx context.Context, session *bloombits.Ma
 	}
 }
 
-func (b *LesApiBackend) GetIPCClient() (*ethclient.Client, error) {
+// func (b *LesApiBackend) GetIPCClient() (*ethclient.Client, error) {
+func (b *LesApiBackend) GetIPCClient() (bind.ContractBackend, error) {
+	// func (b *LesApiBackend) GetIPCClient() (bind.ContractBackend, error) {
 	return nil, nil
 }
 
diff --git a/miner/worker.go b/miner/worker.go
index 537286bd0f..0ea43a9457 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -25,7 +25,6 @@ import (
 	"github.com/XinFinOrg/XDPoSChain/accounts"
 
 	"math/big"
-	"os"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -384,14 +383,6 @@ func (self *worker) wait() {
 				if (block.NumberU64() % work.config.XDPoS.Epoch) == 0 {
 					core.CheckpointCh <- 1
 				}
-				// prepare set of masternodes for the next epoch
-				if (block.NumberU64() % work.config.XDPoS.Epoch) == (work.config.XDPoS.Epoch - work.config.XDPoS.Gap) {
-					err := self.chain.UpdateM1()
-					if err != nil {
-						log.Error("Error when update masternodes set. Stopping node", "err", err)
-						os.Exit(1)
-					}
-				}
 			}
 			self.chain.UpdateBlocksHashCache(block)
 			self.chain.PostChainEvents(events, logs)
diff --git a/params/config.go b/params/config.go
index e3a3ee0009..2523925021 100644
--- a/params/config.go
+++ b/params/config.go
@@ -111,8 +111,12 @@ var (
 	// adding flags to the config to also have to set these fields.
 	AllXDPoSProtocolChanges  = &ChainConfig{big.NewInt(89), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, &XDPoSConfig{Period: 0, Epoch: 30000}}
 	AllCliqueProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}, nil}
-	TestChainConfig          = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, nil}
-	TestRules                = TestChainConfig.Rules(new(big.Int))
+	TestXDPoSMockChainConfig = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, &XDPoSConfig{Epoch: 900, Gap: 450, SkipValidation: true}}
+	TestXDPoSChanConfig      = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, &XDPoSConfig{Period: 2, Epoch: 900, Reward: 250, RewardCheckpoint: 900, Gap: 890, FoudationWalletAddr: common.HexToAddress("0x0000000000000000000000000000000000000068")}}
+	// TestXDPoSMockChainConfig = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, nil, nil, &XDPoSConfig{Epoch: 900, Gap: 890, SkipValidation: true}}
+	// TestXDPoSChainConfig     = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, nil, nil, &XDPoSConfig{Period: 2, Epoch: 900, Reward: 250, RewardCheckpoint: 900, Gap: 890, FoudationWalletAddr: common.HexToAddress("0x0000000000000000000000000000000000000068")}}
+	TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, nil}
+	TestRules       = TestChainConfig.Rules(new(big.Int))
 )
 
 // ChainConfig is the core config which determines the blockchain settings.
@@ -171,6 +175,7 @@ type XDPoSConfig struct {
 	RewardCheckpoint    uint64         `json:"rewardCheckpoint"`    // Checkpoint block for calculate rewards.
 	Gap                 uint64         `json:"gap"`                 // Gap time preparing for the next epoch
 	FoudationWalletAddr common.Address `json:"foudationWalletAddr"` // Foundation Address Wallet
+	SkipValidation      bool           //Skip Block Validation for testing purpose
 }
 
 // String implements the stringer interface, returning the consensus engine details.
diff --git a/tests/block_signer_test.go b/tests/block_signer_test.go
new file mode 100644
index 0000000000..31b492e2dc
--- /dev/null
+++ b/tests/block_signer_test.go
@@ -0,0 +1,842 @@
+package tests
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind"
+	"github.com/XinFinOrg/XDPoSChain/accounts/abi/bind/backends"
+	"github.com/XinFinOrg/XDPoSChain/common"
+	"github.com/XinFinOrg/XDPoSChain/consensus/XDPoS"
+	contractValidator "github.com/XinFinOrg/XDPoSChain/contracts/validator/contract"
+	"github.com/XinFinOrg/XDPoSChain/core"
+	. "github.com/XinFinOrg/XDPoSChain/core"
+	"github.com/XinFinOrg/XDPoSChain/core/types"
+	"github.com/XinFinOrg/XDPoSChain/core/vm"
+	"github.com/XinFinOrg/XDPoSChain/crypto"
+	"github.com/XinFinOrg/XDPoSChain/log"
+	"github.com/XinFinOrg/XDPoSChain/rlp"
+)
+
+type masterNodes map[string]big.Int
+type signersList map[string]bool
+
+const GAP = int(450)
+
+var (
+	acc1Key, _  = crypto.HexToECDSA("8a1f9a8f95be41cd7ccb6168179afb4504aefe388d1e14474d32c45c72ce7b7a")
+	acc2Key, _  = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
+	acc3Key, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+	voterKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee04aefe388d1e14474d32c45c72ce7b7a")
+	acc1Addr    = crypto.PubkeyToAddress(acc1Key.PublicKey)  //xdc703c4b2bD70c169f5717101CaeE543299Fc946C7
+	acc2Addr    = crypto.PubkeyToAddress(acc2Key.PublicKey)  //xdc0D3ab14BBaD3D99F4203bd7a11aCB94882050E7e
+	acc3Addr    = crypto.PubkeyToAddress(acc3Key.PublicKey)  //xdc71562b71999873DB5b286dF957af199Ec94617F7
+	voterAddr   = crypto.PubkeyToAddress(voterKey.PublicKey) //xdc5F74529C0338546f82389402a01c31fB52c6f434
+	chainID     = int64(1337)
+)
+
+func debugMessage(backend *backends.SimulatedBackend, signers signersList, t *testing.T) {
+	ms := GetCandidateFromCurrentSmartContract(backend, t)
+	fmt.Println("=== current smart contract")
+	for nodeAddr, cap := range ms {
+		if !strings.Contains(nodeAddr, "000000000000000000000000000000000000") { //remove defaults
+			fmt.Println(nodeAddr, cap)
+		}
+	}
+	fmt.Println("=== this block signer list")
+	for signer := range signers {
+		if !strings.Contains(signer, "000000000000000000000000000000000000") { //remove defaults
+			fmt.Println(signer)
+		}
+	}
+}
+
+func getCommonBackend(t *testing.T) *backends.SimulatedBackend {
+
+	// initial helper backend
+	contractBackendForSC := backends.NewXDCSimulatedBackend(core.GenesisAlloc{
+		voterAddr: {Balance: new(big.Int).SetUint64(10000000000)},
+	}, 10000000)
+
+	transactOpts := bind.NewKeyedTransactor(voterKey)
+
+	var candidates []common.Address
+	var caps []*big.Int
+	defalutCap := new(big.Int)
+	defalutCap.SetString("1000000000", 10)
+
+	for i := 1; i <= 16; i++ {
+		addr := fmt.Sprintf("%02d", i)
+		candidates = append(candidates, common.StringToAddress(addr)) // StringToAddress does not exist
+		caps = append(caps, defalutCap)
+	}
+
+	acc1Cap, acc2Cap, acc3Cap, voterCap := new(big.Int), new(big.Int), new(big.Int), new(big.Int)
+
+	acc1Cap.SetString("10000001", 10)
+	acc2Cap.SetString("10000002", 10)
+	acc3Cap.SetString("10000003", 10)
+	voterCap.SetString("1000000000", 10)
+
+	caps = append(caps, voterCap, acc1Cap, acc2Cap, acc3Cap)
+	candidates = append(candidates, voterAddr, acc1Addr, acc2Addr, acc3Addr)
+	// create validator smart contract
+	validatorSCAddr, _, _, err := contractValidator.DeployXDCValidator(
+		transactOpts,
+		contractBackendForSC,
+		candidates,
+		caps,
+		voterAddr, // first owner, not used
+		big.NewInt(50000),
+		big.NewInt(1),
+		big.NewInt(99),
+		big.NewInt(100),
+		big.NewInt(100),
+	)
+	if err != nil {
+		t.Fatalf("can't deploy root registry: %v", err)
+	}
+
+	contractBackendForSC.Commit() // Write into database(state)
+
+	// Prepare Code and Storage
+	d := time.Now().Add(1000 * time.Millisecond)
+	ctx, cancel := context.WithDeadline(context.Background(), d)
+	defer cancel()
+
+	code, _ := contractBackendForSC.CodeAt(ctx, validatorSCAddr, nil)
+	storage := make(map[common.Hash]common.Hash)
+	f := func(key, val common.Hash) bool {
+		decode := []byte{}
+		trim := bytes.TrimLeft(val.Bytes(), "\x00")
+		rlp.DecodeBytes(trim, &decode)
+		storage[key] = common.BytesToHash(decode)
+		log.Info("DecodeBytes", "value", val.String(), "decode", storage[key].String())
+		return true
+	}
+	contractBackendForSC.ForEachStorageAt(ctx, validatorSCAddr, nil, f)
+
+	// create test backend with smart contract in it
+	contractBackend2 := backends.NewXDCSimulatedBackend(core.GenesisAlloc{
+		acc1Addr:  {Balance: new(big.Int).SetUint64(10000000000)},
+		acc2Addr:  {Balance: new(big.Int).SetUint64(10000000000)},
+		acc3Addr:  {Balance: new(big.Int).SetUint64(10000000000)},
+		voterAddr: {Balance: new(big.Int).SetUint64(10000000000)},
+		common.HexToAddress(common.MasternodeVotingSMC): {Balance: new(big.Int).SetUint64(1), Code: code, Storage: storage}, // Binding the MasternodeVotingSMC with newly created 'code' for SC execution
+	}, 10000000)
+
+	return contractBackend2
+
+}
+
+func transferTx(t *testing.T, to common.Address, transferAmount int64) *types.Transaction {
+	t.Logf("Transfering %v to address: %v", transferAmount, to.String())
+	data := []byte{}
+	gasPrice := big.NewInt(int64(0))
+	gasLimit := uint64(21000)
+	amount := big.NewInt(transferAmount)
+	nonce := uint64(1)
+	tx := types.NewTransaction(nonce, to, amount, gasLimit, gasPrice, data)
+	signedTX, err := types.SignTx(tx, types.NewEIP155Signer(big.NewInt(chainID)), voterKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return signedTX
+}
+
+/*
+func proposeTX(t *testing.T) *types.Transaction {
+	data := common.Hex2Bytes("012679510000000000000000000000000d3ab14bbad3d99f4203bd7a11acb94882050e7e")
+	//data := []byte{}
+	fmt.Println("data", string(data[:]))
+	gasPrice := big.NewInt(int64(0))
+	gasLimit := uint64(22680)
+	amountInt := new(big.Int)
+	amount, ok := amountInt.SetString("11000000000000000000000000", 10)
+	if !ok {
+		t.Fatal("big int init failed")
+	}
+	nonce := uint64(0)
+	to := common.HexToAddress("xdc35658f7b2a9e7701e65e7a654659eb1c481d1dc5")
+	tx := types.NewTransaction(nonce, to, amount, gasLimit, gasPrice, data)
+	signedTX, err := types.SignTx(tx, types.NewEIP155Signer(big.NewInt(chainID)), acc4Key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return signedTX
+}
+*/
+
+func voteTX(gasLimit uint64, nonce uint64, addr string) (*types.Transaction, error) {
+	vote := "6dd7d8ea" // VoteMethod = "0x6dd7d8ea"
+	action := fmt.Sprintf("%s%s%s", vote, "000000000000000000000000", addr[3:])
+	data := common.Hex2Bytes(action)
+	gasPrice := big.NewInt(int64(0))
+	amountInt := new(big.Int)
+	amount, ok := amountInt.SetString("60000", 10)
+	if !ok {
+		return nil, fmt.Errorf("big int init failed")
+	}
+	to := common.HexToAddress(common.MasternodeVotingSMC)
+	tx := types.NewTransaction(nonce, to, amount, gasLimit, gasPrice, data)
+
+	signedTX, err := types.SignTx(tx, types.NewEIP155Signer(big.NewInt(chainID)), voterKey)
+	if err != nil {
+		return nil, err
+	}
+
+	return signedTX, nil
+}
+
+func UpdateSigner(bc *BlockChain) error {
+	err := bc.UpdateM1()
+	return err
+}
+
+func GetSnapshotSigner(bc *BlockChain, header *types.Header) (signersList, error) {
+	engine := bc.Engine().(*XDPoS.XDPoS)
+	snap, err := engine.GetSnapshot(bc, header)
+	if err != nil {
+		return nil, err
+
+	}
+	ms := make(signersList)
+
+	for addr := range snap.Signers {
+		ms[addr.Hex()] = true
+	}
+	return ms, nil
+
+}
+
+func GetCandidateFromCurrentSmartContract(backend bind.ContractBackend, t *testing.T) masterNodes {
+	addr := common.HexToAddress(common.MasternodeVotingSMC)
+	validator, err := contractValidator.NewXDCValidator(addr, backend)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	opts := new(bind.CallOpts)
+	candidates, err := validator.GetCandidates(opts)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ms := make(masterNodes)
+	for _, candidate := range candidates {
+		v, err := validator.GetCandidateCap(opts, candidate)
+		if err != nil {
+			t.Fatal(err)
+		}
+		ms[candidate.String()] = *v
+	}
+	return ms
+}
+
+func PrepareXDCTestBlockChain(t *testing.T, numOfBlocks int) (*BlockChain, *backends.SimulatedBackend, *types.Block) {
+	// Preparation
+	var err error
+	backend := getCommonBackend(t)
+	blockchain := backend.GetBlockChain()
+	blockchain.Client = backend
+
+	currentBlock := blockchain.Genesis()
+
+	// Insert initial blocks
+	for i := 1; i <= numOfBlocks; i++ {
+		blockCoinBase := fmt.Sprintf("0x111000000000000000000000000000000%03d", i)
+		merkleRoot := "35999dded35e8db12de7e6c1471eb9670c162eec616ecebbaf4fddd4676fb930"
+		block, err := insertBlock(blockchain, i, blockCoinBase, currentBlock, merkleRoot)
+		if err != nil {
+			t.Fatal(err)
+		}
+		currentBlock = block
+	}
+	// Update Signer as there is no previous signer assigned
+	err = UpdateSigner(blockchain)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return blockchain, backend, currentBlock
+}
+
+// insert Block without transcation attached
+func insertBlock(blockchain *BlockChain, blockNum int, blockCoinBase string, parentBlock *types.Block, root string) (*types.Block, error) {
+	block, err := createXDPoSTestBlock(
+		blockchain,
+		parentBlock.Hash().Hex(),
+		blockCoinBase, blockNum, nil,
+		"0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
+		common.HexToHash(root),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	err = blockchain.InsertBlock(block)
+	if err != nil {
+		return nil, err
+	}
+	return block, nil
+}
+
+// insert Block with transcation attached
+func insertBlockTxs(blockchain *BlockChain, blockNum int, blockCoinBase string, parentBlock *types.Block, txs []*types.Transaction, root string) (*types.Block, error) {
+	block, err := createXDPoSTestBlock(
+		blockchain,
+		parentBlock.Hash().Hex(),
+		blockCoinBase, blockNum, txs,
+		"0x9319777b782ba2c83a33c995481ff894ac96d9a92a1963091346a3e1e386705c",
+		common.HexToHash(root),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	err = blockchain.InsertBlock(block)
+	if err != nil {
+		return nil, err
+	}
+	return block, nil
+}
+
+func createXDPoSTestBlock(bc *BlockChain, parentHash, coinbase string, number int, txs []*types.Transaction, receiptHash string, root common.Hash) (*types.Block, error) {
+	extraSubstring := "d7830100018358444388676f312e31342e31856c696e75780000000000000000b185dc0d0e917d18e5dbf0746be6597d3331dd27ea0554e6db433feb2e81730b20b2807d33a1527bf43cd3bc057aa7f641609c2551ebe2fd575f4db704fbf38101" // Grabbed from existing mainnet block, it does not have any meaning except for the length validation
+	//ReceiptHash = "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421"
+	//Root := "0xc99c095e53ff1afe3b86750affd13c7550a2d24d51fb8e41b3c3ef2ea8274bcc"
+	extraByte, _ := hex.DecodeString(extraSubstring)
+	header := types.Header{
+		ParentHash: common.HexToHash(parentHash),
+		UncleHash:  types.EmptyUncleHash,
+		TxHash:     types.EmptyRootHash,
+		// ReceiptHash: types.EmptyRootHash,
+		ReceiptHash: common.HexToHash(receiptHash),
+		Root:        root,
+		Coinbase:    common.HexToAddress(coinbase),
+		Difficulty:  big.NewInt(int64(1)),
+		Number:      big.NewInt(int64(number)),
+		GasLimit:    1200000000,
+		Time:        uint64(number * 10),
+		Extra:       extraByte,
+	}
+
+	var block *types.Block
+	if len(txs) == 0 {
+		block = types.NewBlockWithHeader(&header)
+	} else {
+
+		// Prepare Receipt
+		statedb, err := bc.StateAt(bc.GetBlockByNumber(uint64(number - 1)).Root()) //Get parent root
+		if err != nil {
+			return nil, fmt.Errorf("%v when get state", err)
+		}
+		gp := new(GasPool).AddGas(header.GasLimit)
+		// usedGas := uint64(0)
+
+		var gasUsed = new(uint64)
+		var receipts types.Receipts
+		for i, tx := range txs {
+			statedb.Prepare(tx.Hash(), header.Hash(), i)
+			receipt, _, err := ApplyTransaction(bc.Config(), bc, &header.Coinbase, gp, statedb, &header, tx, gasUsed, vm.Config{})
+			if err != nil {
+				return nil, fmt.Errorf("%v when applying transaction", err)
+			}
+			receipts = append(receipts, receipt)
+		}
+
+		header.GasUsed = *gasUsed
+
+		block = types.NewBlock(&header, txs, nil, receipts)
+	}
+
+	return block, nil
+}
+
+// Should NOT update signerList if not on the gap block
+func TestNotUpdateSignerListIfNotOnGapBlock(t *testing.T) {
+	blockchain, backend, parentBlock := PrepareXDCTestBlockChain(t, 400)
+	parentSigners, err := GetSnapshotSigner(blockchain, parentBlock.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Inserting block with propose at 401")
+	blockCoinbaseA := "0xaaa0000000000000000000000000000000000401"
+	tx, err := voteTX(37117, 0, acc1Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	//Get from block validator error message
+	merkleRoot := "46234e9cd7e85a267f7f0435b15256a794a2f6d65cc98cdbd21dcd10a01d9772"
+	blockA, err := insertBlockTxs(blockchain, 401, blockCoinbaseA, parentBlock, []*types.Transaction{tx}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signers, err := GetSnapshotSigner(blockchain, blockA.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if signers[acc1Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should NOT sit in the signer list")
+	}
+	eq := reflect.DeepEqual(parentSigners, signers)
+	if eq {
+		t.Logf("Signers unchanged")
+	} else {
+		t.Fatalf("Singers should not be changed!")
+	}
+}
+
+// Should call updateM1 at the gap block, and have the same snapshot values as the parent block if no SM transaction is involved
+func TestNotChangeSingerListIfNothingProposedOrVoted(t *testing.T) {
+	blockchain, _, parentBlock := PrepareXDCTestBlockChain(t, GAP-1)
+	// Insert block 450
+	blockCoinBase := fmt.Sprintf("0x111000000000000000000000000000000%03d", 450)
+	merkleRoot := "35999dded35e8db12de7e6c1471eb9670c162eec616ecebbaf4fddd4676fb930"
+	block, err := insertBlock(blockchain, 450, blockCoinBase, parentBlock, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+	parentSigners, err := GetSnapshotSigner(blockchain, parentBlock.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	signers, err := GetSnapshotSigner(blockchain, block.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	eq := reflect.DeepEqual(parentSigners, signers)
+	if eq {
+		t.Logf("Signers unchanged")
+	} else {
+		t.Fatalf("Singers should not be changed!")
+	}
+}
+
+//Should call updateM1 at gap block, and update the snapshot if there are SM transactions involved
+func TestUpdateSignerListIfVotedBeforeGap(t *testing.T) {
+
+	blockchain, backend, parentBlock := PrepareXDCTestBlockChain(t, GAP-2)
+	// Insert first Block 449
+	t.Logf("Inserting block with propose at 449...")
+	blockCoinbaseA := "0xaaa0000000000000000000000000000000000449"
+	tx, err := voteTX(37117, 0, acc1Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	//Get from block validator error message
+	merkleRoot := "46234e9cd7e85a267f7f0435b15256a794a2f6d65cc98cdbd21dcd10a01d9772"
+	block449, err := insertBlockTxs(blockchain, 449, blockCoinbaseA, parentBlock, []*types.Transaction{tx}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+	parentBlock = block449
+
+	signers, err := GetSnapshotSigner(blockchain, block449.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	// At block 449, we should not update signerList. we need to update it till block 450 gap block.
+	// Acc3 is the default account that is on the signerList
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 3 should sit in the signer list")
+	}
+	if signers[acc1Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should NOT sit in the signer list")
+	}
+
+	// Now, let's mine another block to trigger the GAP block signerList update
+	block450CoinbaseAddress := "0xaaa0000000000000000000000000000000000450"
+	merkleRoot = "46234e9cd7e85a267f7f0435b15256a794a2f6d65cc98cdbd21dcd10a01d9772"
+	block450, err := insertBlock(blockchain, 450, block450CoinbaseAddress, parentBlock, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, block450.Header())
+	// Now, we voted acc 1 to be in the signerList, which will kick out acc3 because it has less funds
+	if signers[acc3Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 3 should NOT sit in the signer list")
+	}
+	if signers[acc1Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should sit in the signer list")
+	}
+}
+
+//Should call updateM1 before gap block, and update the snapshot if there are SM transactions involved
+func TestCallUpdateM1WithSmartContractTranscation(t *testing.T) {
+
+	blockchain, backend, currentBlock := PrepareXDCTestBlockChain(t, GAP-1)
+	// Insert first Block 450 A
+	t.Logf("Inserting block with propose at 450 A...")
+	blockCoinbaseA := "0xaaa0000000000000000000000000000000000450"
+	tx, err := voteTX(37117, 0, acc1Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	//Get from block validator error message
+	merkleRoot := "46234e9cd7e85a267f7f0435b15256a794a2f6d65cc98cdbd21dcd10a01d9772"
+	blockA, err := insertBlockTxs(blockchain, 450, blockCoinbaseA, currentBlock, []*types.Transaction{tx}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signers, err := GetSnapshotSigner(blockchain, blockA.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc1Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should sit in the signer list")
+	}
+}
+
+// Should call updateM1 and update snapshot when a forked block(at gap block number) is inserted back into main chain (Edge case)
+func TestCallUpdateM1WhenForkedBlockBackToMainChain(t *testing.T) {
+
+	blockchain, backend, currentBlock := PrepareXDCTestBlockChain(t, GAP-1)
+	// Check initial signer, by default, acc3 is in the signerList
+	signers, err := GetSnapshotSigner(blockchain, blockchain.CurrentBlock().Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc3 should sit in the signer list")
+	}
+	if (signers[acc1Addr.Hex()] == true) || (signers[acc2Addr.Hex()] == true) {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc1,2should NOT sit in the signer list")
+	}
+
+	// Insert first Block 450 A
+	t.Logf("Inserting block with propose at 450 A...")
+	blockCoinbaseA := "0xaaa0000000000000000000000000000000000450"
+	tx, err := voteTX(37117, 0, acc1Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	merkleRoot := "46234e9cd7e85a267f7f0435b15256a794a2f6d65cc98cdbd21dcd10a01d9772"
+	blockA, err := insertBlockTxs(blockchain, 450, blockCoinbaseA, currentBlock, []*types.Transaction{tx}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, blockA.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc1Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should sit in the signer list")
+	}
+	if signers[acc2Addr.Hex()] == true || signers[acc3Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 2,3 should NOT sit in the signer list")
+	}
+
+	// Insert forked Block 450 B
+	t.Logf("Inserting block with propose for acc2 at 450 B...")
+
+	blockCoinBase450B := "0xbbb0000000000000000000000000000000000450"
+	tx, err = voteTX(37117, 0, acc2Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	merkleRoot = "068dfa09d7b4093441c0cc4d9807a71bc586f6101c072d939b214c21cd136eb3"
+	block450B, err := insertBlockTxs(blockchain, 450, blockCoinBase450B, currentBlock, []*types.Transaction{tx}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+	signers, err = GetSnapshotSigner(blockchain, block450B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Should not run the `updateM1` for forked chain, hence account3 still exit
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 3 should sit in the signer list as previos block result")
+	}
+	if (signers[acc1Addr.Hex()] == true) || (signers[acc2Addr.Hex()] == true) {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc1,2should NOT sit in the signer list")
+	}
+
+	//Insert block 451 parent is 451 B
+	t.Logf("Inserting block with propose at 451 B...")
+
+	blockCoinBase451B := "0xbbb0000000000000000000000000000000000451"
+	merkleRoot = "068dfa09d7b4093441c0cc4d9807a71bc586f6101c072d939b214c21cd136eb3"
+	block451B, err := insertBlock(blockchain, 451, blockCoinBase451B, block450B, merkleRoot)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, block450B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc2Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 2 should sit in the signer list")
+	}
+	if signers[acc1Addr.Hex()] == true || signers[acc3Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc1,3should NOT sit in the signer list")
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, block451B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc2Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 2 should sit in the signer list")
+	}
+	if signers[acc1Addr.Hex()] == true || signers[acc3Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc1,3should NOT sit in the signer list")
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, blockchain.CurrentBlock().Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc2Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc2Addr should sit in the signer list")
+	}
+	if signers[acc1Addr.Hex()] == true || signers[acc3Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc1,3should NOT sit in the signer list")
+	}
+}
+
+func TestStatesShouldBeUpdatedWhenForkedBlockBecameMainChainAtGapBlock(t *testing.T) {
+
+	blockchain, backend, parentBlock := PrepareXDCTestBlockChain(t, GAP-1)
+
+	state, err := blockchain.State()
+	t.Logf("Account %v have balance of: %v", acc1Addr.String(), state.GetBalance(acc1Addr))
+	// Check initial signer
+	signers, err := GetSnapshotSigner(blockchain, blockchain.CurrentBlock().Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc3Addr should sit in the signer list")
+	}
+
+	// Insert first Block 450 A
+	t.Logf("Inserting block with propose and transfer at 450 A...")
+	blockCoinbaseA := "0xaaa0000000000000000000000000000000000450"
+	tx, err := voteTX(58117, 0, acc1Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	transferTransaction := transferTx(t, acc1Addr, 999)
+
+	merkleRoot := "ea465415b60d88429f181fec9fae67c0f19cbf5a4fa10971d96d4faa57d96ffa"
+	blockA, err := insertBlockTxs(blockchain, 450, blockCoinbaseA, parentBlock, []*types.Transaction{tx, transferTransaction}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+	state, err = blockchain.State()
+	t.Log("After transfer transaction at block 450 A, Account 1 have balance of: ", state.GetBalance(acc1Addr))
+
+	if state.GetBalance(acc1Addr).Cmp(new(big.Int).SetUint64(10000000999)) != 0 {
+		t.Fatalf("account 1 should have 10000000999 in balance")
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, blockA.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc1Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should sit in the signer list")
+	}
+
+	// Insert forked Block 450 B
+	t.Logf("Inserting block with propose at 450 B...")
+
+	blockCoinBase450B := "0xbbb0000000000000000000000000000000000450"
+	tx, err = voteTX(37117, 0, acc2Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	transferTransaction = transferTx(t, acc1Addr, 888)
+
+	merkleRoot = "184edaddeafc2404248f896ae46be503ae68949896c8eb6b6ad43695581e5022"
+	block450B, err := insertBlockTxs(blockchain, 450, blockCoinBase450B, parentBlock, []*types.Transaction{tx, transferTransaction}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+	state, err = blockchain.State()
+	if state.GetBalance(acc1Addr).Cmp(new(big.Int).SetUint64(10000000999)) != 0 {
+		t.Fatalf("account 1 should have 10000000999 in balance as the block is forked, not on the main chain")
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, block450B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Should not run the `updateM1` for forked chain, hence account3 still exit
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 3 should sit in the signer list as previos block result")
+	}
+
+	//Insert block 451 parent is 451 B
+	t.Logf("Inserting block with propose at 451 B...")
+
+	blockCoinBase451B := "0xbbb0000000000000000000000000000000000451"
+	merkleRoot = "184edaddeafc2404248f896ae46be503ae68949896c8eb6b6ad43695581e5022"
+	block451B, err := insertBlock(blockchain, 451, blockCoinBase451B, block450B, merkleRoot)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, block450B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc2Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 2 should sit in the signer list")
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, block451B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc2Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 2 should sit in the signer list")
+	}
+
+	signers, err = GetSnapshotSigner(blockchain, blockchain.CurrentBlock().Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc2Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc2Addr should sit in the signer list")
+	}
+	state, err = blockchain.State()
+	t.Log("After transfer transaction at block 450 B and the B fork has been merged into main chain, Account 1 have balance of: ", state.GetBalance(acc1Addr))
+
+	if state.GetBalance(acc1Addr).Cmp(new(big.Int).SetUint64(10000000888)) != 0 {
+		t.Fatalf("account 1 should have 10000000888 in balance")
+	}
+}
+
+func TestVoteShouldNotBeAffectedByFork(t *testing.T) {
+	blockchain, backend, parentBlock := PrepareXDCTestBlockChain(t, GAP-1)
+	// Check initial signer, by default, acc3 is in the signerList
+	signers, err := GetSnapshotSigner(blockchain, blockchain.CurrentBlock().Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc3 should sit in the signer list")
+	}
+	if (signers[acc1Addr.Hex()] == true) || (signers[acc2Addr.Hex()] == true) {
+		debugMessage(backend, signers, t)
+		t.Fatalf("acc1,2should NOT sit in the signer list")
+	}
+
+	// Insert normal blocks 450 A
+	blockCoinBase450A := "0xaaa0000000000000000000000000000000000450"
+	merkleRoot := "35999dded35e8db12de7e6c1471eb9670c162eec616ecebbaf4fddd4676fb930"
+	block450A, err := insertBlock(blockchain, 450, blockCoinBase450A, parentBlock, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Insert 451 A with vote
+	blockCoinbase451A := "0xaaa0000000000000000000000000000000000451"
+	tx, err := voteTX(37117, 0, acc1Addr.String())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	merkleRoot = "46234e9cd7e85a267f7f0435b15256a794a2f6d65cc98cdbd21dcd10a01d9772"
+	block451A, err := insertBlockTxs(blockchain, 451, blockCoinbase451A, block450A, []*types.Transaction{tx}, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// SignerList should be unchanged as the vote happen after GAP block
+	signers, err = GetSnapshotSigner(blockchain, block451A.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if signers[acc1Addr.Hex()] == true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 1 should NOT sit in the signer list")
+	}
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 3 should sit in the signer list")
+	}
+
+	// Now, we going to inject normal blocks of 450B, 451B and 452B. Because it's the longest, it will become the mainchain
+	// Insert forked Block 450 B
+	blockCoinBase450B := "0xbbb0000000000000000000000000000000000450"
+	merkleRoot = "35999dded35e8db12de7e6c1471eb9670c162eec616ecebbaf4fddd4676fb930"
+	block450B, err := insertBlock(blockchain, 450, blockCoinBase450B, parentBlock, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	blockCoinBase451B := "0xbbb0000000000000000000000000000000000451"
+	merkleRoot = "35999dded35e8db12de7e6c1471eb9670c162eec616ecebbaf4fddd4676fb930"
+	block451B, err := insertBlock(blockchain, 451, blockCoinBase451B, block450B, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	blockCoinBase452B := "0xbbb0000000000000000000000000000000000452"
+	merkleRoot = "35999dded35e8db12de7e6c1471eb9670c162eec616ecebbaf4fddd4676fb930"
+	block452B, err := insertBlock(blockchain, 452, blockCoinBase452B, block451B, merkleRoot)
+	if err != nil {
+		t.Fatal(err)
+	}
+	signers, err = GetSnapshotSigner(blockchain, block452B.Header())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Should run the `updateM1` for forked chain, but it should not be affected by the voted block 451A which is not on the mainchain anymore
+	if signers[acc3Addr.Hex()] != true {
+		debugMessage(backend, signers, t)
+		t.Fatalf("account 3 should sit in the signer list as previos block result")
+	}
+}