diff --git a/consensus/replay_test.go b/consensus/replay_test.go
index af0af3e7..a1e06c65 100644
--- a/consensus/replay_test.go
+++ b/consensus/replay_test.go
@@ -264,9 +264,12 @@ func (w *crashingWAL) Wait()        { w.next.Wait() }
 //------------------------------------------------------------------------------------------
 // Handshake Tests
 
+const (
+	NUM_BLOCKS = 6
+)
+
 var (
-	NUM_BLOCKS = 6 // number of blocks in the test_data/many_blocks.cswal
-	mempool    = types.MockMempool{}
+	mempool = types.MockMempool{}
 )
 
 //---------------------------------------
@@ -305,12 +308,12 @@ func TestHandshakeReplayNone(t *testing.T) {
 	}
 }
 
-func writeWAL(walMsgs []byte) string {
+func tempWALWithData(data []byte) string {
 	walFile, err := ioutil.TempFile("", "wal")
 	if err != nil {
 		panic(fmt.Errorf("failed to create temp WAL file: %v", err))
 	}
-	_, err = walFile.Write(walMsgs)
+	_, err = walFile.Write(data)
 	if err != nil {
 		panic(fmt.Errorf("failed to write to temp WAL file: %v", err))
 	}
@@ -324,12 +327,11 @@ func writeWAL(walMsgs []byte) string {
 func testHandshakeReplay(t *testing.T, nBlocks int, mode uint) {
 	config := ResetConfig("proxy_test_")
 
-	// copy the many_blocks file
-	walBody, err := cmn.ReadFile(path.Join(data_dir, "many_blocks.cswal"))
+	walBody, err := WALWithNBlocks(NUM_BLOCKS)
 	if err != nil {
 		t.Fatal(err)
 	}
-	walFile := writeWAL(walBody)
+	walFile := tempWALWithData(walBody)
 	config.Consensus.SetWalFile(walFile)
 
 	privVal := types.LoadPrivValidatorFS(config.PrivValidatorFile())
diff --git a/consensus/test_data/README.md b/consensus/test_data/README.md
deleted file mode 100644
index 822f16c0..00000000
--- a/consensus/test_data/README.md
+++ /dev/null
@@ -1,36 +0,0 @@
-# Generating test data
-
-To generate the data, run `build.sh`. See that script for more details.
-
-Make sure to adjust the stepChanges in the testCases if the number of messages changes.
-This sometimes happens for the `small_block2.cswal`, where the number of block parts changes between 4 and 5.
-
-If you need to change the signatures, you can use a script as follows:
-The privBytes comes from `config/tendermint_test/...`:
-
-```
-package main
-
-import (
-	"encoding/hex"
-	"fmt"
-
-	"github.com/tendermint/go-crypto"
-)
-
-func main() {
-	signBytes, err := hex.DecodeString("7B22636861696E5F6964223A2274656E6465726D696E745F74657374222C22766F7465223A7B22626C6F636B5F68617368223A2242453544373939433846353044354645383533364334333932464443384537423342313830373638222C22626C6F636B5F70617274735F686561646572223A506172745365747B543A31204236323237323535464632307D2C22686569676874223A312C22726F756E64223A302C2274797065223A327D7D")
-	if err != nil {
-		panic(err)
-	}
-	privBytes, err := hex.DecodeString("27F82582AEFAE7AB151CFB01C48BB6C1A0DA78F9BDDA979A9F70A84D074EB07D3B3069C422E19688B45CBFAE7BB009FC0FA1B1EA86593519318B7214853803C8")
-	if err != nil {
-		panic(err)
-	}
-	privKey := crypto.PrivKeyEd25519{}
-	copy(privKey[:], privBytes)
-	signature := privKey.Sign(signBytes)
-	fmt.Printf("Signature Bytes: %X\n", signature.Bytes())
-}
-```
-
diff --git a/consensus/test_data/build.sh b/consensus/test_data/build.sh
deleted file mode 100755
index 6f410c70..00000000
--- a/consensus/test_data/build.sh
+++ /dev/null
@@ -1,148 +0,0 @@
-#!/usr/bin/env bash
-
-# Requires: killall command and jq JSON processor.
-
-# Get the parent directory of where this script is.
-SOURCE="${BASH_SOURCE[0]}"
-while [ -h "$SOURCE" ] ; do SOURCE="$(readlink "$SOURCE")"; done
-DIR="$( cd -P "$( dirname "$SOURCE" )/../.." && pwd )"
-
-# Change into that dir because we expect that.
-cd "$DIR" || exit 1
-
-# Make sure we have a tendermint command.
-if ! hash tendermint 2>/dev/null; then
-	make install
-fi
-
-# Make sure we have a cutWALUntil binary.
-cutWALUntil=./scripts/cutWALUntil/cutWALUntil
-cutWALUntilDir=$(dirname $cutWALUntil)
-if ! hash $cutWALUntil 2>/dev/null; then
-	cd "$cutWALUntilDir" && go build && cd - || exit 1
-fi
-
-TMHOME=$(mktemp -d)
-export TMHOME="$TMHOME"
-
-if [[ ! -d "$TMHOME" ]]; then
-	echo "Could not create temp directory"
-  exit 1
-else
-	echo "TMHOME: ${TMHOME}"
-fi
-
-# TODO: eventually we should replace with `tendermint init --test`
-DIR_TO_COPY=$HOME/.tendermint_test/consensus_state_test
-if [ ! -d "$DIR_TO_COPY" ]; then
-    echo "$DIR_TO_COPY does not exist. Please run: go test ./consensus"
-    exit 1
-fi
-echo "==> Copying ${DIR_TO_COPY} to ${TMHOME} directory..."
-cp -r "$DIR_TO_COPY"/* "$TMHOME"
-
-# preserve original genesis file because later it will be modified (see small_block2)
-cp "$TMHOME/genesis.json" "$TMHOME/genesis.json.bak"
-
-function reset(){
-	echo "==> Resetting tendermint..."
-	tendermint unsafe_reset_all
-	cp "$TMHOME/genesis.json.bak" "$TMHOME/genesis.json"
-}
-
-reset
-
-# function empty_block(){
-# 	echo "==> Starting tendermint..."
-# 	tendermint node --proxy_app=persistent_dummy &> /dev/null &
-# 	sleep 5
-# 	echo "==> Killing tendermint..."
-# 	killall tendermint
-
-# 	echo "==> Copying WAL log..."
-# 	$cutWALUntil "$TMHOME/data/cs.wal/wal" 1 consensus/test_data/new_empty_block.cswal
-# 	mv consensus/test_data/new_empty_block.cswal consensus/test_data/empty_block.cswal
-
-# 	reset
-# }
-
-function many_blocks(){
-	bash scripts/txs/random.sh 1000 36657 &> /dev/null &
-	PID=$!
-	echo "==> Starting tendermint..."
-	tendermint node --proxy_app=persistent_dummy &> /dev/null &
-	sleep 10
-	echo "==> Killing tendermint..."
-	kill -9 $PID
-	killall tendermint
-
-	echo "==> Copying WAL log..."
-	$cutWALUntil "$TMHOME/data/cs.wal/wal" 6 consensus/test_data/new_many_blocks.cswal
-	mv consensus/test_data/new_many_blocks.cswal consensus/test_data/many_blocks.cswal
-
-	reset
-}
-
-
-# function small_block1(){
-# 	bash scripts/txs/random.sh 1000 36657 &> /dev/null &
-# 	PID=$!
-# 	echo "==> Starting tendermint..."
-# 	tendermint node --proxy_app=persistent_dummy &> /dev/null &
-# 	sleep 10
-# 	echo "==> Killing tendermint..."
-# 	kill -9 $PID
-# 	killall tendermint
-
-# 	echo "==> Copying WAL log..."
-# 	$cutWALUntil "$TMHOME/data/cs.wal/wal" 1 consensus/test_data/new_small_block1.cswal
-# 	mv consensus/test_data/new_small_block1.cswal consensus/test_data/small_block1.cswal
-
-# 	reset
-# }
-
-
-# # block part size = 512
-# function small_block2(){
-# 	cat "$TMHOME/genesis.json" | jq '. + {consensus_params: {block_size_params: {max_bytes: 22020096}, block_gossip_params: {block_part_size_bytes: 512}}}' > "$TMHOME/new_genesis.json"
-# 	mv "$TMHOME/new_genesis.json" "$TMHOME/genesis.json"
-# 	bash scripts/txs/random.sh 1000 36657 &> /dev/null &
-# 	PID=$!
-# 	echo "==> Starting tendermint..."
-# 	tendermint node --proxy_app=persistent_dummy &> /dev/null &
-# 	sleep 5
-# 	echo "==> Killing tendermint..."
-# 	kill -9 $PID
-# 	killall tendermint
-
-# 	echo "==> Copying WAL log..."
-# 	$cutWALUntil "$TMHOME/data/cs.wal/wal" 1 consensus/test_data/new_small_block2.cswal
-# 	mv consensus/test_data/new_small_block2.cswal consensus/test_data/small_block2.cswal
-
-# 	reset
-# }
-
-
-
-case "$1" in
-	# "small_block1")
-	# 	small_block1
-	# 	;;
-	# "small_block2")
-	# 	small_block2
-	# 	;;
-	# "empty_block")
-	# 	empty_block
-	# 	;;
-	"many_blocks")
-		many_blocks
-		;;
-	*)
-		# small_block1
-		# small_block2
-		# empty_block
-		many_blocks
-esac
-
-echo "==> Cleaning up..."
-rm -rf "$TMHOME"
diff --git a/consensus/test_data/many_blocks.cswal b/consensus/test_data/many_blocks.cswal
deleted file mode 100644
index 2af0c3cc..00000000
Binary files a/consensus/test_data/many_blocks.cswal and /dev/null differ
diff --git a/consensus/wal.go b/consensus/wal.go
index 69519c16..c6367c7d 100644
--- a/consensus/wal.go
+++ b/consensus/wal.go
@@ -30,7 +30,7 @@ type TimedWALMessage struct {
 }
 
 // EndHeightMessage marks the end of the given height inside WAL.
-// @internal used by scripts/cutWALUntil util.
+// @internal used by scripts/wal2json util.
 type EndHeightMessage struct {
 	Height int64 `json:"height"`
 }
diff --git a/consensus/wal_generator.go b/consensus/wal_generator.go
new file mode 100644
index 00000000..8a2e2182
--- /dev/null
+++ b/consensus/wal_generator.go
@@ -0,0 +1,181 @@
+package consensus
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/tendermint/abci/example/dummy"
+	bc "github.com/tendermint/tendermint/blockchain"
+	cfg "github.com/tendermint/tendermint/config"
+	"github.com/tendermint/tendermint/proxy"
+	sm "github.com/tendermint/tendermint/state"
+	"github.com/tendermint/tendermint/types"
+	auto "github.com/tendermint/tmlibs/autofile"
+	"github.com/tendermint/tmlibs/db"
+	"github.com/tendermint/tmlibs/log"
+)
+
+// WALWithNBlocks generates a consensus WAL. It does this by spining up a
+// stripped down version of node (proxy app, event bus, consensus state) with a
+// persistent dummy application and special consensus wal instance
+// (byteBufferWAL) and waits until numBlocks are created. Then it returns a WAL
+// content.
+func WALWithNBlocks(numBlocks int) (data []byte, err error) {
+	config := getConfig()
+
+	app := dummy.NewPersistentDummyApplication(filepath.Join(config.DBDir(), "wal_generator"))
+
+	logger := log.NewNopLogger() // log.TestingLogger().With("wal_generator", "wal_generator")
+
+	/////////////////////////////////////////////////////////////////////////////
+	// COPY PASTE FROM node.go WITH A FEW MODIFICATIONS
+	// NOTE: we can't import node package because of circular dependency
+	privValidatorFile := config.PrivValidatorFile()
+	privValidator := types.LoadOrGenPrivValidatorFS(privValidatorFile)
+	genDoc, err := types.GenesisDocFromFile(config.GenesisFile())
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to read genesis file")
+	}
+	stateDB := db.NewMemDB()
+	blockStoreDB := db.NewMemDB()
+	state, err := sm.MakeGenesisState(stateDB, genDoc)
+	state.SetLogger(logger.With("module", "state"))
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to make genesis state")
+	}
+	blockStore := bc.NewBlockStore(blockStoreDB)
+	handshaker := NewHandshaker(state, blockStore)
+	proxyApp := proxy.NewAppConns(proxy.NewLocalClientCreator(app), handshaker)
+	proxyApp.SetLogger(logger.With("module", "proxy"))
+	if err := proxyApp.Start(); err != nil {
+		return nil, errors.Wrap(err, "failed to start proxy app connections")
+	}
+	defer proxyApp.Stop()
+	eventBus := types.NewEventBus()
+	eventBus.SetLogger(logger.With("module", "events"))
+	if err := eventBus.Start(); err != nil {
+		return nil, errors.Wrap(err, "failed to start event bus")
+	}
+	mempool := types.MockMempool{}
+	consensusState := NewConsensusState(config.Consensus, state.Copy(), proxyApp.Consensus(), blockStore, mempool)
+	consensusState.SetLogger(logger)
+	consensusState.SetEventBus(eventBus)
+	if privValidator != nil {
+		consensusState.SetPrivValidator(privValidator)
+	}
+	// END OF COPY PASTE
+	/////////////////////////////////////////////////////////////////////////////
+
+	// set consensus wal to buffered WAL, which will write all incoming msgs to buffer
+	var b bytes.Buffer
+	wr := bufio.NewWriter(&b)
+	numBlocksWritten := make(chan struct{})
+	wal := &byteBufferWAL{enc: NewWALEncoder(wr), heightToStop: int64(numBlocks), signalWhenStopsTo: numBlocksWritten}
+	// see wal.go#103
+	wal.Save(EndHeightMessage{0})
+	consensusState.wal = wal
+
+	if err := consensusState.Start(); err != nil {
+		return nil, errors.Wrap(err, "failed to start consensus state")
+	}
+	defer consensusState.Stop()
+
+	select {
+	case <-numBlocksWritten:
+		wr.Flush()
+		return b.Bytes(), nil
+	case <-time.After(time.Duration(2*numBlocks) * time.Second):
+		return b.Bytes(), fmt.Errorf("waited too long for tendermint to produce %d blocks", numBlocks)
+	}
+}
+
+// f**ing long, but unique for each test
+func makePathname() string {
+	// get path
+	p, err := os.Getwd()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(p)
+	sep := string(filepath.Separator)
+	return strings.Replace(p, sep, "_", -1)
+}
+
+func randPort() int {
+	// returns between base and base + spread
+	base, spread := 20000, 20000
+	return base + rand.Intn(spread)
+}
+
+func makeAddrs() (string, string, string) {
+	start := randPort()
+	return fmt.Sprintf("tcp://0.0.0.0:%d", start),
+		fmt.Sprintf("tcp://0.0.0.0:%d", start+1),
+		fmt.Sprintf("tcp://0.0.0.0:%d", start+2)
+}
+
+// getConfig returns a config for test cases
+func getConfig() *cfg.Config {
+	pathname := makePathname()
+	c := cfg.ResetTestRoot(pathname)
+
+	// and we use random ports to run in parallel
+	tm, rpc, grpc := makeAddrs()
+	c.P2P.ListenAddress = tm
+	c.RPC.ListenAddress = rpc
+	c.RPC.GRPCListenAddress = grpc
+	return c
+}
+
+// byteBufferWAL is a WAL which writes all msgs to a byte buffer. Writing stops
+// when the heightToStop is reached. Client will be notified via
+// signalWhenStopsTo channel.
+type byteBufferWAL struct {
+	enc               *WALEncoder
+	stopped           bool
+	heightToStop      int64
+	signalWhenStopsTo chan struct{}
+}
+
+// needed for determinism
+var fixedTime, _ = time.Parse(time.RFC3339, "2017-01-02T15:04:05Z")
+
+// Save writes message to the internal buffer except when heightToStop is
+// reached, in which case it will signal the caller via signalWhenStopsTo and
+// skip writing.
+func (w *byteBufferWAL) Save(m WALMessage) {
+	if w.stopped {
+		return
+	}
+
+	if endMsg, ok := m.(EndHeightMessage); ok {
+		if endMsg.Height == w.heightToStop {
+			w.signalWhenStopsTo <- struct{}{}
+			w.stopped = true
+			return
+		}
+	}
+
+	err := w.enc.Encode(&TimedWALMessage{fixedTime, m})
+	if err != nil {
+		panic(fmt.Sprintf("failed to encode the msg %v", m))
+	}
+}
+
+func (w *byteBufferWAL) Group() *auto.Group {
+	panic("not implemented")
+}
+func (w *byteBufferWAL) SearchForEndHeight(height int64) (gr *auto.GroupReader, found bool, err error) {
+	return nil, false, nil
+}
+
+func (w *byteBufferWAL) Start() error { return nil }
+func (w *byteBufferWAL) Stop() error  { return nil }
+func (w *byteBufferWAL) Wait()        {}
diff --git a/consensus/wal_test.go b/consensus/wal_test.go
index 38f2ce03..8ec1a7c2 100644
--- a/consensus/wal_test.go
+++ b/consensus/wal_test.go
@@ -3,7 +3,6 @@ package consensus
 import (
 	"bytes"
 	"crypto/rand"
-	"path"
 	"sync"
 	"testing"
 	"time"
@@ -43,7 +42,13 @@ func TestWALEncoderDecoder(t *testing.T) {
 }
 
 func TestSearchForEndHeight(t *testing.T) {
-	wal, err := NewWAL(path.Join(data_dir, "many_blocks.cswal"), false)
+	walBody, err := WALWithNBlocks(6)
+	if err != nil {
+		t.Fatal(err)
+	}
+	walFile := tempWALWithData(walBody)
+
+	wal, err := NewWAL(walFile, false)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/scripts/cutWALUntil/main.go b/scripts/cutWALUntil/main.go
deleted file mode 100644
index 84336895..00000000
--- a/scripts/cutWALUntil/main.go
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
-	cutWALUntil is a small utility for cutting a WAL until the given height
-	(inclusively). Note it does not include last cs.EndHeightMessage.
-
-	Usage:
-			cutWALUntil <path-to-wal> height-to-stop <output-wal>
-*/
-package main
-
-import (
-	"fmt"
-	"io"
-	"os"
-	"strconv"
-
-	cs "github.com/tendermint/tendermint/consensus"
-)
-
-func main() {
-	if len(os.Args) < 4 {
-		fmt.Println("3 arguments required: <path-to-wal> <height-to-stop> <output-wal>")
-		os.Exit(1)
-	}
-
-	var heightToStop int64
-	var err error
-	if heightToStop, err = strconv.ParseInt(os.Args[2], 10, 64); err != nil {
-		panic(fmt.Errorf("failed to parse height: %v", err))
-	}
-
-	in, err := os.Open(os.Args[1])
-	if err != nil {
-		panic(fmt.Errorf("failed to open input WAL file: %v", err))
-	}
-	defer in.Close()
-
-	out, err := os.Create(os.Args[3])
-	if err != nil {
-		panic(fmt.Errorf("failed to open output WAL file: %v", err))
-	}
-	defer out.Close()
-
-	enc := cs.NewWALEncoder(out)
-	dec := cs.NewWALDecoder(in)
-
-	for {
-		msg, err := dec.Decode()
-		if err == io.EOF {
-			break
-		} else if err != nil {
-			panic(fmt.Errorf("failed to decode msg: %v", err))
-		}
-
-		if m, ok := msg.Msg.(cs.EndHeightMessage); ok {
-			if m.Height == heightToStop {
-				break
-			}
-		}
-
-		err = enc.Encode(msg)
-		if err != nil {
-			panic(fmt.Errorf("failed to encode msg: %v", err))
-		}
-	}
-}