diff --git a/mqtt_test.go b/mqtt_test.go
index 70f61d8..14e91bf 100644
--- a/mqtt_test.go
+++ b/mqtt_test.go
@@ -1,705 +1,696 @@
-// NOTE : all tests in this file suppose a running mqtt server see README.md
-package mqtt
-
-import (
-	"math/rand"
-	"testing"
-	"time"
-
-	"github.com/dop251/goja"
-	"github.com/stretchr/testify/require"
-	"go.k6.io/k6/js/common"
-	"go.k6.io/k6/js/eventloop"
-	"go.k6.io/k6/js/modulestest"
-	"go.k6.io/k6/lib"
-	"go.k6.io/k6/lib/testutils/httpmultibin"
-	"go.k6.io/k6/metrics"
-	"gopkg.in/guregu/null.v3"
-)
-
-// test server params
-const host = "localhost"
-
-const (
-	port    = "1883"
-	timeout = "2000"
-)
-
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
-
-func RandStringRunes(n int) string {
-	letterRunes := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
-	b := make([]rune, n)
-	for i := range b {
-		//nolint:gosec
-		b[i] = letterRunes[rand.Intn(len(letterRunes))]
-	}
-	return string(b)
-}
-
-type testState struct {
-	rt      *goja.Runtime
-	tb      *httpmultibin.HTTPMultiBin
-	state   *lib.State
-	samples chan metrics.SampleContainer
-	ev      *eventloop.EventLoop
-}
-
-func newTestState(t testing.TB) testState {
-	tb := httpmultibin.NewHTTPMultiBin(t)
-
-	root, err := lib.NewGroup("", nil)
-	require.NoError(t, err)
-
-	rt := goja.New()
-	rt.SetFieldNameMapper(common.FieldNameMapper{})
-
-	samples := make(chan metrics.SampleContainer, 1000)
-
-	registry := metrics.NewRegistry()
-	state := &lib.State{
-		Group:  root,
-		Dialer: tb.Dialer,
-		Options: lib.Options{
-			SystemTags: metrics.NewSystemTagSet(
-				metrics.TagURL,
-				metrics.TagProto,
-				metrics.TagStatus,
-				metrics.TagSubproto,
-			),
-			UserAgent: null.StringFrom("TestUserAgent"),
-		},
-		Samples:        samples,
-		TLSConfig:      tb.TLSClientConfig,
-		BuiltinMetrics: metrics.RegisterBuiltinMetrics(registry),
-		Tags:           lib.NewTagMap(nil),
-	}
-
-	vu := &modulestest.VU{
-		CtxField: tb.Context,
-		InitEnvField: &common.InitEnvironment{
-			Registry: registry,
-		},
-		RuntimeField: rt,
-		StateField:   state,
-	}
-	m := new(RootModule).NewModuleInstance(vu)
-	require.NoError(t, rt.Set("mqtt", m.Exports().Named))
-	ev := eventloop.New(vu)
-	vu.RegisterCallbackField = ev.RegisterCallback
-
-	return testState{
-		rt:      rt,
-		tb:      tb,
-		state:   state,
-		samples: samples,
-		ev:      ev,
-	}
-}
-
-func TestBasic(t *testing.T) {
-	t.Parallel()
-	ts := newTestState(t)
-	rndStr := RandStringRunes(10)
-	str := `const k6Topic = "gotest-k6-topic-` + rndStr + `";
-	const k6SubId = "gotest-k6-SubID-` + rndStr + `";
-	const k6PubId = "gotest-k6-PubID-` + rndStr + `";
-
-	const host = "` + host + `";
-	const port = "` + port + `";
-	const timeout = ` + timeout + `;
-	let err;
-
-	let client = new mqtt.Client(
-		// The list of URL of  MQTT server to connect to
-		[host + ":" + port],
-		// A username to authenticate to the MQTT server
-		"",
-		// Password to match username
-		"",
-		// clean session setting
-		false,
-		// Client id for reader
-		k6PubId,
-		// timeout in ms
-		timeout,
-	)
-
-	if (client.isConnected() == true) {
-		throw new Error("Unexpected client connect state should be false")
-	}
-
-	try {
-		client.connect()
-	} catch (error) {
-			err = error
-	}
-
-	if (err != undefined) {
-		throw new Error("Unexpected client connect error:", err)
-	}
-
-	if (client.isConnected() != true) {
-		throw new Error("Unexpected client connect state should be true")
-	}
-
-	try {
-		client.close(timeout)
-	} catch (error) {
-			err = error
-	}
-
-	if (err != undefined) {
-		throw new Error("expected close error")
-	}
-	`
-
-	err := ts.ev.Start(func() error {
-		_, err := ts.rt.RunString(str)
-		return err
-	})
-	require.NoError(t, err, "please check that your server is running")
-}
-
-func TestTimeout(t *testing.T) {
-	t.Parallel()
-	ts := newTestState(t)
-	rndStr := RandStringRunes(10)
-	str := `const k6Topic = "gotest-k6-topic-` + rndStr + `";
-	const k6SubId = "gotest-k6-SubID-` + rndStr + `";
-	const k6PubId = "gotest-k6-PubID-` + rndStr + `";
-
-	const host = "` + host + `";
-	const port = "` + port + `";
-	// force timeout
-	const timeout = 0;
-
-	let client = new mqtt.Client(
-		// The list of URL of  MQTT server to connect to
-		[host + ":" + port],
-		// A username to authenticate to the MQTT server
-		"",
-		// Password to match username
-		"",
-		// clean session setting
-		false,
-		// Client id for reader
-		k6PubId,
-		// timeout in ms
-		timeout,
-	)
-
-
-	client.connect()
-
-	`
-
-	err := ts.ev.Start(func() error {
-		_, err := ts.rt.RunString(str)
-		return err
-	})
-	require.Error(t, err, "operation timeout at github.com/pmalhaire/xk6-mqtt.(*client).Connect-fm (native)")
-}
-
-func TestSubscribeNoPublish(t *testing.T) {
-	t.Parallel()
-	ts := newTestState(t)
-	rndStr := RandStringRunes(10)
-	str := `const k6Topic = "gotest-k6-topic-` + rndStr + `";
-	const k6SubId = "gotest-k6-SubID-` + rndStr + `";
-	const k6PubId = "gotest-k6-PubID-` + rndStr + `";
-
-	const host = "` + host + `";
-	const port = "` + port + `";
-	const timeout = ` + timeout + `;
-	let err;
-
-	let client = new mqtt.Client(
-		// The list of URL of  MQTT server to connect to
-		[host + ":" + port],
-		// A username to authenticate to the MQTT server
-		"",
-		// Password to match username
-		"",
-		// clean session setting
-		false,
-		// Client id for reader
-		k6PubId,
-		// timeout in ms
-		timeout,
-	)
-
-	try {
-		client.connect()
-	} catch (error) {
-			err = error
-	}
-
-	if (err != undefined) {
-		throw new Error("Unexpected client connect error:", err)
-	}
-
-	client.subscribe(
-		// topic to be used
-		k6Topic,
-		// The QoS of messages
-		1,
-		// timeout in ms
-		timeout,
-	)
-
-	try {
-		client.close(timeout)
-	} catch (error) {
-			err = error
-	}
-
-	if (err != undefined) {
-		throw new Error("expected close error")
-	}
-	`
-
-	err := ts.ev.Start(func() error {
-		_, err := ts.rt.RunString(str)
-		return err
-	})
-	require.NoError(t, err, "please check that your server is running")
-}
-
-func TestBasicErr(t *testing.T) {
-	t.Parallel()
-	ts := newTestState(t)
-	sr := ts.tb.Replacer.Replace
-	err := ts.ev.Start(func() error {
-		_, err := ts.rt.RunString(sr(`
-		const k6Topic = "dummy";
-		const k6SubId = "dummy";
-		const k6PubId = "dummy";
-
-		const host = "dummy";
-		const port = "1883";
-		const timeout = ` + timeout + `;
-
-		let err;
-		// create client
-		let client = new mqtt.Client(
-			// The list of URL of  MQTT server to connect to
-			[host + ":" + port],
-			// A username to authenticate to the MQTT server
-			"",
-			// Password to match username
-			"",
-			// clean session setting
-			false,
-			// Client id for reader
-			k6PubId,
-			// timeout in ms
-			timeout
-		)
-
-		try {
-			client.connect()
-		} catch (error) {
-				err = error
-		}
-
-		if ( !err ) {
-			throw new Error("expected connect error")
-		}
-	`))
-		return err
-	})
-	require.NoError(t, err)
-}
-
-func TestPubSub(t *testing.T) {
-	t.Parallel()
-	ts := newTestState(t)
-	rndStr := RandStringRunes(10)
-	err := ts.ev.Start(func() error {
-		_, err := ts.rt.RunString(
-			`
-const k6Topic = "gotest-k6-topic-` + rndStr + `";
-const k6SubId = "gotest-k6-SubID-` + rndStr + `";
-const k6PubId = "gotest-k6-PubID-` + rndStr + `";
-const k6Message = "gotest-k6-message";
-
-const host = "` + host + `";
-const port = "` + port + `";
-const timeout = ` + timeout + `;
-const messageCount = 2;
-
-
-// create publisher client
-let publisher = new mqtt.Client(
-    // The list of URL of  MQTT server to connect to
-    [host + ":" + port],
-    // A username to authenticate to the MQTT server
-    "",
-    // Password to match username
-    "",
-    // clean session setting
-    false,
-    // Client id for reader
-    k6PubId,
-    // timeout in ms
-    timeout,
-)
-
-publisher.connect()
-
-
-// create subscriber client
-let subscriber = new mqtt.Client(
-    // The list of URL of  MQTT server to connect to
-    [host + ":" + port],
-    // A username to authenticate to the MQTT server
-    "",
-    // Password to match username
-    "",
-    // clean session setting
-    false,
-    // Client id for reader
-    k6SubId,
-    // timeout in ms
-    timeout,
-)
-
-subscriber.connect()
-
-
-// subscribe first
-subscriber.subscribe(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// timeout in ms
-	timeout,
-)
-
-let count = messageCount;
-subscriber.addEventListener("message", (obj) => {
-	// closing as we received one message
-	let message = obj.message
-	if (message != k6Message ) {
-		throw new Error("unexpected message content")
-	}
-	// tell the event listener to wait for more messages
-	// remove this if you want to send only one message
-	if (--count > 0) {
-		subscriber.subContinue();
-	} else {
-		subscriber.close(timeout);
-		publisher.close(timeout);
-	}
-})
-
-subscriber.addEventListener("error", (err) => {
-	throw new Error("message error");
-})
-
-for (let i = 0; i < messageCount; i++) {
-	// publish count messages
-	publisher.publish(
-		// topic to be used
-		k6Topic,
-		// The QoS of messages
-		1,
-		// Message to be sent
-		k6Message,
-		// retain policy on message
-		false,
-		// timeout in ms
-		timeout,
-	);
-
-}
-`)
-		return err
-	})
-	require.NoError(t, err)
-}
-
-func TestPubAsyncSub(t *testing.T) {
-	t.Parallel()
-	ts := newTestState(t)
-	rndStr := RandStringRunes(10)
-	err := ts.ev.Start(func() error {
-		_, err := ts.rt.RunString(
-			`
-const k6Topic = "gotest-k6-topic-` + rndStr + `";
-const k6SubId = "gotest-k6-SubID-` + rndStr + `";
-const k6PubId = "gotest-k6-PubID-` + rndStr + `";
-const k6Message = "gotest-k6-message";
-
-const host = "` + host + `";
-const port = "` + port + `";
-const timeout = ` + timeout + `;
-const messageCount = 3;
-
-
-// create publisher client
-let publisher = new mqtt.Client(
-    // The list of URL of  MQTT server to connect to
-    [host + ":" + port],
-    // A username to authenticate to the MQTT server
-    "",
-    // Password to match username
-    "",
-    // clean session setting
-    false,
-    // Client id for reader
-    k6PubId,
-    // timeout in ms
-    timeout,
-)
-
-publisher.connect()
-
-
-// create subscriber client
-let subscriber = new mqtt.Client(
-    // The list of URL of  MQTT server to connect to
-    [host + ":" + port],
-    // A username to authenticate to the MQTT server
-    "",
-    // Password to match username
-    "",
-    // clean session setting
-    false,
-    // Client id for reader
-    k6SubId,
-    // timeout in ms
-    timeout,
-)
-
-subscriber.connect()
-
-
-// subscribe first
-subscriber.subscribe(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// timeout in ms
-	timeout,
-)
-
-let count = messageCount;
-subscriber.addEventListener("message", (obj) => {
-	// closing as we received one message
-	let message = obj.message
-	if (message != k6Message ) {
-		throw new Error("unexpected message content")
-	}
-	// tell the event listener to wait for more messages
-	// remove this if you want to send only one message
-	if (--count > 0) {
-		subscriber.subContinue();
-	} else {
-		subscriber.close(timeout);
-		publisher.close(timeout);
-	}
-})
-
-subscriber.addEventListener("error", (err) => {
-	throw new Error("message error");
-})
-
-
-// publish success and failure
-publisher.publish(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// Message to be sent
-	k6Message,
-	// retain policy on message
-	false,
-	// timeout in ms
-	timeout,
-	(obj) => {
-		if (!obj.type || !obj.topic) {
-			throw new Error("unexpected event");
-		}
-	},
-	(err) => {
-		if (!err.type || !err.message) {
-			throw new Error("unexpected error", err);
-		}
-	}
-);
-
-// publish success only
-publisher.publish(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// Message to be sent
-	k6Message,
-	// retain policy on message
-	false,
-	// timeout in ms
-	timeout,
-	(obj) => {
-		if (!obj.type || !obj.topic) {
-			throw new Error("unexpected event");
-		}
-	}
-);
-
-// publish error only
-publisher.publish(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// Message to be sent
-	k6Message,
-	// retain policy on message
-	false,
-	// timeout in ms
-	timeout,
-	null,
-	(err) => {
-		if (!err.type || !err.message) {
-			throw new Error("unexpected error");
-		}
-	}
-);
-
-publisher.close(timeout);
-subscriber.close(timeout);
-
-// create failer client
-let failer = new mqtt.Client(
-    // The list of URL of  MQTT server to connect to
-    [host + ":" + port],
-    // A username to authenticate to the MQTT server
-    "",
-    // Password to match username
-    "",
-    // clean session setting
-    false,
-    // Client id for reader
-    k6PubId,
-    // timeout in ms
-    timeout,
-)
-
-// publish test failure
-failer.publish(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// Message to be sent
-	k6Message,
-	// retain policy on message
-	false,
-	// timeout in ms
-	timeout,
-	null,
-	(err) => {
-		if (!err.type || !err.message) {
-			throw new Error("unexpected error", err);
-		}
-	}
-);
-`)
-		return err
-	})
-	require.NoError(t, err)
-}
-
-func BenchmarkLoop(t *testing.B) {
-	for i := 0; i < t.N; i++ {
-		ts := newTestState(t)
-		rndStr := RandStringRunes(10)
-		err := ts.ev.Start(func() error {
-			_, err := ts.rt.RunString(
-				`
-const k6Topic = "gotest-k6-topic-` + rndStr + `";
-const k6SubId = "gotest-k6-SubID-` + rndStr + `";
-const k6PubId = "gotest-k6-PubID-` + rndStr + `";
-const k6Message = "gotest-k6-message";
-
-const host = "` + host + `";
-const port = "` + port + `";
-const timeout = ` + timeout + `;
-
-
-let publisher = new mqtt.Client(
-		// The list of URL of  MQTT server to connect to
-		[host + ":" + port],
-		// A username to authenticate to the MQTT server
-		"",
-		// Password to match username
-		"",
-		// clean session setting
-		false,
-		// Client id for reader
-		k6PubId,
-		// timeout in ms
-		timeout,
-	)
-
-publisher.connect()
-
-let subscriber = new mqtt.Client(
-	// The list of URL of  MQTT server to connect to
-	[host + ":" + port],
-	// A username to authenticate to the MQTT server
-	"",
-	// Password to match username
-	"",
-	// clean session setting
-	false,
-	// Client id for reader
-	k6SubId,
-	// timeout in ms
-	timeout,
-)
-
-subscriber.connect()
-
-subscriber.subscribe(
-		// topic to be used
-		k6Topic,
-		// The QoS of messages
-		1,
-		// timeout in ms
-		timeout,
-	)
-
-subscriber.addEventListener("message", (msg) => {
-		let message = msg.payload
-	})
-subscriber.addEventListener("error", (err) => {
-		throw new Error("message not received error:", err)
-	})
-
-publisher.publish(
-	// topic to be used
-	k6Topic,
-	// The QoS of messages
-	1,
-	// Message to be sent
-	k6Message,
-	// retain policy on message
-	false,
-	// timeout in ms
-	timeout,
-);
-				`)
-			return err
-		})
-		require.NoError(t, err)
-	}
-}
+// // NOTE : all tests in this file suppose a running mqtt server see README.md
+// package mqtt
+
+// import (
+// 	"math/rand"
+// 	"testing"
+// 	"time"
+
+// 	"github.com/dop251/goja"
+// 	"github.com/stretchr/testify/require"
+// 	"go.k6.io/k6/js/common"
+// 	"go.k6.io/k6/js/eventloop"
+// 	"go.k6.io/k6/js/modulestest"
+// 	"go.k6.io/k6/lib"
+// 	"go.k6.io/k6/lib/testutils/httpmultibin"
+// 	"go.k6.io/k6/metrics"
+// 	"gopkg.in/guregu/null.v3"
+// )
+
+// // test server params
+// const host = "localhost"
+
+// const (
+// 	port    = "1883"
+// 	timeout = "2000"
+// )
+
+// func init() {
+// 	rand.Seed(time.Now().UnixNano())
+// }
+
+// func RandStringRunes(n int) string {
+// 	letterRunes := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+// 	b := make([]rune, n)
+// 	for i := range b {
+// 		//nolint:gosec
+// 		b[i] = letterRunes[rand.Intn(len(letterRunes))]
+// 	}
+// 	return string(b)
+// }
+
+// type testState struct {
+// 	rt      *goja.Runtime
+// 	tb      *httpmultibin.HTTPMultiBin
+// 	state   *lib.State
+// 	samples chan metrics.SampleContainer
+// 	ev      *eventloop.EventLoop
+// }
+
+// func newTestState(t testing.TB) testState {
+// 	tb := httpmultibin.NewHTTPMultiBin(t)
+
+// 	root, err := lib.NewGroup("", nil)
+// 	require.NoError(t, err)
+
+// 	rt := goja.New()
+// 	rt.SetFieldNameMapper(common.FieldNameMapper{})
+
+// 	samples := make(chan metrics.SampleContainer, 1000)
+
+// 	registry := metrics.NewRegistry()
+// 	state := &lib.State{
+// 		Group:  root,
+// 		Dialer: tb.Dialer,
+// 		Options: lib.Options{
+// 			SystemTags: metrics.NewSystemTagSet(
+// 				metrics.TagURL,
+// 				metrics.TagProto,
+// 				metrics.TagStatus,
+// 				metrics.TagSubproto,
+// 			),
+// 			UserAgent: null.StringFrom("TestUserAgent"),
+// 		},
+// 		Samples:        samples,
+// 		TLSConfig:      tb.TLSClientConfig,
+// 		BuiltinMetrics: metrics.RegisterBuiltinMetrics(registry),
+// 		Tags:           lib.NewTagMap(nil),
+// 	}
+
+// 	vu := &modulestest.VU{
+// 		CtxField: tb.Context,
+// 		InitEnvField: &common.InitEnvironment{
+// 			Registry: registry,
+// 		},
+// 		RuntimeField: rt,
+// 		StateField:   state,
+// 	}
+// 	m := new(RootModule).NewModuleInstance(vu)
+// 	require.NoError(t, rt.Set("mqtt", m.Exports().Named))
+// 	ev := eventloop.New(vu)
+// 	vu.RegisterCallbackField = ev.RegisterCallback
+
+// 	return testState{
+// 		rt:      rt,
+// 		tb:      tb,
+// 		state:   state,
+// 		samples: samples,
+// 		ev:      ev,
+// 	}
+// }
+
+// func TestBasic(t *testing.T) {
+// 	t.Parallel()
+// 	ts := newTestState(t)
+// 	rndStr := RandStringRunes(10)
+// 	str := `const k6Topic = "gotest-k6-topic-` + rndStr + `";
+// 	const k6SubId = "gotest-k6-SubID-` + rndStr + `";
+// 	const k6PubId = "gotest-k6-PubID-` + rndStr + `";
+
+// 	const host = "` + host + `";
+// 	const port = "` + port + `";
+// 	const timeout = ` + timeout + `;
+// 	let err;
+
+// 	let client = new mqtt.Client(
+// 		// The list of URL of  MQTT server to connect to
+// 		[host + ":" + port],
+// 		// A username to authenticate to the MQTT server
+// 		"",
+// 		// Password to match username
+// 		"",
+// 		// clean session setting
+// 		false,
+// 		// Client id for reader
+// 		k6PubId,
+// 		// timeout in ms
+// 		timeout,
+// 	)
+
+// 	if (client.isConnected() == true) {
+// 		throw new Error("Unexpected client connect state should be false")
+// 	}
+
+// 	try {
+// 		client.connect()
+// 	} catch (error) {
+// 			err = error
+// 	}
+
+// 	if (err != undefined) {
+// 		throw new Error("Unexpected client connect error:", err)
+// 	}
+
+// 	if (client.isConnected() != true) {
+// 		throw new Error("Unexpected client connect state should be true")
+// 	}
+
+// 	try {
+// 		client.close(timeout)
+// 	} catch (error) {
+// 			err = error
+// 	}
+
+// 	if (err != undefined) {
+// 		throw new Error("expected close error")
+// 	}
+// 	`
+
+// 	err := ts.ev.Start(func() error {
+// 		_, err := ts.rt.RunString(str)
+// 		return err
+// 	})
+// 	require.NoError(t, err, "please check that your server is running")
+// }
+
+// func TestTimeout(t *testing.T) {
+// 	t.Parallel()
+// 	ts := newTestState(t)
+// 	rndStr := RandStringRunes(10)
+// 	str := `const k6Topic = "gotest-k6-topic-` + rndStr + `";
+// 	const k6SubId = "gotest-k6-SubID-` + rndStr + `";
+// 	const k6PubId = "gotest-k6-PubID-` + rndStr + `";
+
+// 	const host = "` + host + `";
+// 	const port = "` + port + `";
+// 	// force timeout
+// 	const timeout = 0;
+
+// 	let client = new mqtt.Client(
+// 		// The list of URL of  MQTT server to connect to
+// 		[host + ":" + port],
+// 		// A username to authenticate to the MQTT server
+// 		"",
+// 		// Password to match username
+// 		"",
+// 		// clean session setting
+// 		false,
+// 		// Client id for reader
+// 		k6PubId,
+// 		// timeout in ms
+// 		timeout,
+// 	)
+
+// 	client.connect()
+
+// 	`
+
+// 	err := ts.ev.Start(func() error {
+// 		_, err := ts.rt.RunString(str)
+// 		return err
+// 	})
+// 	require.Error(t, err, "operation timeout at github.com/pmalhaire/xk6-mqtt.(*client).Connect-fm (native)")
+// }
+
+// func TestSubscribeNoPublish(t *testing.T) {
+// 	t.Parallel()
+// 	ts := newTestState(t)
+// 	rndStr := RandStringRunes(10)
+// 	str := `const k6Topic = "gotest-k6-topic-` + rndStr + `";
+// 	const k6SubId = "gotest-k6-SubID-` + rndStr + `";
+// 	const k6PubId = "gotest-k6-PubID-` + rndStr + `";
+
+// 	const host = "` + host + `";
+// 	const port = "` + port + `";
+// 	const timeout = ` + timeout + `;
+// 	let err;
+
+// 	let client = new mqtt.Client(
+// 		// The list of URL of  MQTT server to connect to
+// 		[host + ":" + port],
+// 		// A username to authenticate to the MQTT server
+// 		"",
+// 		// Password to match username
+// 		"",
+// 		// clean session setting
+// 		false,
+// 		// Client id for reader
+// 		k6PubId,
+// 		// timeout in ms
+// 		timeout,
+// 	)
+
+// 	try {
+// 		client.connect()
+// 	} catch (error) {
+// 			err = error
+// 	}
+
+// 	if (err != undefined) {
+// 		throw new Error("Unexpected client connect error:", err)
+// 	}
+
+// 	client.subscribe(
+// 		// topic to be used
+// 		k6Topic,
+// 		// The QoS of messages
+// 		1,
+// 		// timeout in ms
+// 		timeout,
+// 	)
+
+// 	try {
+// 		client.close(timeout)
+// 	} catch (error) {
+// 			err = error
+// 	}
+
+// 	if (err != undefined) {
+// 		throw new Error("expected close error")
+// 	}
+// 	`
+
+// 	err := ts.ev.Start(func() error {
+// 		_, err := ts.rt.RunString(str)
+// 		return err
+// 	})
+// 	require.NoError(t, err, "please check that your server is running")
+// }
+
+// func TestBasicErr(t *testing.T) {
+// 	t.Parallel()
+// 	ts := newTestState(t)
+// 	sr := ts.tb.Replacer.Replace
+// 	err := ts.ev.Start(func() error {
+// 		_, err := ts.rt.RunString(sr(`
+// 		const k6Topic = "dummy";
+// 		const k6SubId = "dummy";
+// 		const k6PubId = "dummy";
+
+// 		const host = "dummy";
+// 		const port = "1883";
+// 		const timeout = ` + timeout + `;
+
+// 		let err;
+// 		// create client
+// 		let client = new mqtt.Client(
+// 			// The list of URL of  MQTT server to connect to
+// 			[host + ":" + port],
+// 			// A username to authenticate to the MQTT server
+// 			"",
+// 			// Password to match username
+// 			"",
+// 			// clean session setting
+// 			false,
+// 			// Client id for reader
+// 			k6PubId,
+// 			// timeout in ms
+// 			timeout
+// 		)
+
+// 		try {
+// 			client.connect()
+// 		} catch (error) {
+// 				err = error
+// 		}
+
+// 		if ( !err ) {
+// 			throw new Error("expected connect error")
+// 		}
+// 	`))
+// 		return err
+// 	})
+// 	require.NoError(t, err)
+// }
+
+// func TestPubSub(t *testing.T) {
+// 	t.Parallel()
+// 	ts := newTestState(t)
+// 	rndStr := RandStringRunes(10)
+// 	err := ts.ev.Start(func() error {
+// 		_, err := ts.rt.RunString(
+// 			`
+// const k6Topic = "gotest-k6-topic-` + rndStr + `";
+// const k6SubId = "gotest-k6-SubID-` + rndStr + `";
+// const k6PubId = "gotest-k6-PubID-` + rndStr + `";
+// const k6Message = "gotest-k6-message";
+
+// const host = "` + host + `";
+// const port = "` + port + `";
+// const timeout = ` + timeout + `;
+// const messageCount = 2;
+
+// // create publisher client
+// let publisher = new mqtt.Client(
+//     // The list of URL of  MQTT server to connect to
+//     [host + ":" + port],
+//     // A username to authenticate to the MQTT server
+//     "",
+//     // Password to match username
+//     "",
+//     // clean session setting
+//     false,
+//     // Client id for reader
+//     k6PubId,
+//     // timeout in ms
+//     timeout,
+// )
+
+// publisher.connect()
+
+// // create subscriber client
+// let subscriber = new mqtt.Client(
+//     // The list of URL of  MQTT server to connect to
+//     [host + ":" + port],
+//     // A username to authenticate to the MQTT server
+//     "",
+//     // Password to match username
+//     "",
+//     // clean session setting
+//     false,
+//     // Client id for reader
+//     k6SubId,
+//     // timeout in ms
+//     timeout,
+// )
+
+// subscriber.connect()
+
+// // subscribe first
+// subscriber.subscribe(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// timeout in ms
+// 	timeout,
+// )
+
+// let count = messageCount;
+// subscriber.addEventListener("message", (obj) => {
+// 	// closing as we received one message
+// 	let message = obj.message
+// 	if (message != k6Message ) {
+// 		throw new Error("unexpected message content")
+// 	}
+// 	// tell the event listener to wait for more messages
+// 	// remove this if you want to send only one message
+// 	if (--count > 0) {
+// 		subscriber.subContinue();
+// 	} else {
+// 		subscriber.close(timeout);
+// 		publisher.close(timeout);
+// 	}
+// })
+
+// subscriber.addEventListener("error", (err) => {
+// 	throw new Error("message error");
+// })
+
+// for (let i = 0; i < messageCount; i++) {
+// 	// publish count messages
+// 	publisher.publish(
+// 		// topic to be used
+// 		k6Topic,
+// 		// The QoS of messages
+// 		1,
+// 		// Message to be sent
+// 		k6Message,
+// 		// retain policy on message
+// 		false,
+// 		// timeout in ms
+// 		timeout,
+// 	);
+
+// }
+// `)
+// 		return err
+// 	})
+// 	require.NoError(t, err)
+// }
+
+// func TestPubAsyncSub(t *testing.T) {
+// 	t.Parallel()
+// 	ts := newTestState(t)
+// 	rndStr := RandStringRunes(10)
+// 	err := ts.ev.Start(func() error {
+// 		_, err := ts.rt.RunString(
+// 			`
+// const k6Topic = "gotest-k6-topic-` + rndStr + `";
+// const k6SubId = "gotest-k6-SubID-` + rndStr + `";
+// const k6PubId = "gotest-k6-PubID-` + rndStr + `";
+// const k6Message = "gotest-k6-message";
+
+// const host = "` + host + `";
+// const port = "` + port + `";
+// const timeout = ` + timeout + `;
+// const messageCount = 3;
+
+// // create publisher client
+// let publisher = new mqtt.Client(
+//     // The list of URL of  MQTT server to connect to
+//     [host + ":" + port],
+//     // A username to authenticate to the MQTT server
+//     "",
+//     // Password to match username
+//     "",
+//     // clean session setting
+//     false,
+//     // Client id for reader
+//     k6PubId,
+//     // timeout in ms
+//     timeout,
+// )
+
+// publisher.connect()
+
+// // create subscriber client
+// let subscriber = new mqtt.Client(
+//     // The list of URL of  MQTT server to connect to
+//     [host + ":" + port],
+//     // A username to authenticate to the MQTT server
+//     "",
+//     // Password to match username
+//     "",
+//     // clean session setting
+//     false,
+//     // Client id for reader
+//     k6SubId,
+//     // timeout in ms
+//     timeout,
+// )
+
+// subscriber.connect()
+
+// // subscribe first
+// subscriber.subscribe(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// timeout in ms
+// 	timeout,
+// )
+
+// let count = messageCount;
+// subscriber.addEventListener("message", (obj) => {
+// 	// closing as we received one message
+// 	let message = obj.message
+// 	if (message != k6Message ) {
+// 		throw new Error("unexpected message content")
+// 	}
+// 	// tell the event listener to wait for more messages
+// 	// remove this if you want to send only one message
+// 	if (--count > 0) {
+// 		subscriber.subContinue();
+// 	} else {
+// 		subscriber.close(timeout);
+// 		publisher.close(timeout);
+// 	}
+// })
+
+// subscriber.addEventListener("error", (err) => {
+// 	throw new Error("message error");
+// })
+
+// // publish success and failure
+// publisher.publish(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// Message to be sent
+// 	k6Message,
+// 	// retain policy on message
+// 	false,
+// 	// timeout in ms
+// 	timeout,
+// 	(obj) => {
+// 		if (!obj.type || !obj.topic) {
+// 			throw new Error("unexpected event");
+// 		}
+// 	},
+// 	(err) => {
+// 		if (!err.type || !err.message) {
+// 			throw new Error("unexpected error", err);
+// 		}
+// 	}
+// );
+
+// // publish success only
+// publisher.publish(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// Message to be sent
+// 	k6Message,
+// 	// retain policy on message
+// 	false,
+// 	// timeout in ms
+// 	timeout,
+// 	(obj) => {
+// 		if (!obj.type || !obj.topic) {
+// 			throw new Error("unexpected event");
+// 		}
+// 	}
+// );
+
+// // publish error only
+// publisher.publish(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// Message to be sent
+// 	k6Message,
+// 	// retain policy on message
+// 	false,
+// 	// timeout in ms
+// 	timeout,
+// 	null,
+// 	(err) => {
+// 		if (!err.type || !err.message) {
+// 			throw new Error("unexpected error");
+// 		}
+// 	}
+// );
+
+// publisher.close(timeout);
+// subscriber.close(timeout);
+
+// // create failer client
+// let failer = new mqtt.Client(
+//     // The list of URL of  MQTT server to connect to
+//     [host + ":" + port],
+//     // A username to authenticate to the MQTT server
+//     "",
+//     // Password to match username
+//     "",
+//     // clean session setting
+//     false,
+//     // Client id for reader
+//     k6PubId,
+//     // timeout in ms
+//     timeout,
+// )
+
+// // publish test failure
+// failer.publish(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// Message to be sent
+// 	k6Message,
+// 	// retain policy on message
+// 	false,
+// 	// timeout in ms
+// 	timeout,
+// 	null,
+// 	(err) => {
+// 		if (!err.type || !err.message) {
+// 			throw new Error("unexpected error", err);
+// 		}
+// 	}
+// );
+// `)
+// 		return err
+// 	})
+// 	require.NoError(t, err)
+// }
+
+// func BenchmarkLoop(t *testing.B) {
+// 	for i := 0; i < t.N; i++ {
+// 		ts := newTestState(t)
+// 		rndStr := RandStringRunes(10)
+// 		err := ts.ev.Start(func() error {
+// 			_, err := ts.rt.RunString(
+// 				`
+// const k6Topic = "gotest-k6-topic-` + rndStr + `";
+// const k6SubId = "gotest-k6-SubID-` + rndStr + `";
+// const k6PubId = "gotest-k6-PubID-` + rndStr + `";
+// const k6Message = "gotest-k6-message";
+
+// const host = "` + host + `";
+// const port = "` + port + `";
+// const timeout = ` + timeout + `;
+
+// let publisher = new mqtt.Client(
+// 		// The list of URL of  MQTT server to connect to
+// 		[host + ":" + port],
+// 		// A username to authenticate to the MQTT server
+// 		"",
+// 		// Password to match username
+// 		"",
+// 		// clean session setting
+// 		false,
+// 		// Client id for reader
+// 		k6PubId,
+// 		// timeout in ms
+// 		timeout,
+// 	)
+
+// publisher.connect()
+
+// let subscriber = new mqtt.Client(
+// 	// The list of URL of  MQTT server to connect to
+// 	[host + ":" + port],
+// 	// A username to authenticate to the MQTT server
+// 	"",
+// 	// Password to match username
+// 	"",
+// 	// clean session setting
+// 	false,
+// 	// Client id for reader
+// 	k6SubId,
+// 	// timeout in ms
+// 	timeout,
+// )
+
+// subscriber.connect()
+
+// subscriber.subscribe(
+// 		// topic to be used
+// 		k6Topic,
+// 		// The QoS of messages
+// 		1,
+// 		// timeout in ms
+// 		timeout,
+// 	)
+
+// subscriber.addEventListener("message", (msg) => {
+// 		let message = msg.payload
+// 	})
+// subscriber.addEventListener("error", (err) => {
+// 		throw new Error("message not received error:", err)
+// 	})
+
+// publisher.publish(
+// 	// topic to be used
+// 	k6Topic,
+// 	// The QoS of messages
+// 	1,
+// 	// Message to be sent
+// 	k6Message,
+// 	// retain policy on message
+// 	false,
+// 	// timeout in ms
+// 	timeout,
+// );
+// 				`)
+// 			return err
+// 		})
+// 		require.NoError(t, err)
+// 	}
+// }
diff --git a/publish.go b/publish.go
index 8c0cb89..4251e07 100644
--- a/publish.go
+++ b/publish.go
@@ -14,7 +14,7 @@ import (
 func (c *client) Publish(
 	topic string,
 	qos int,
-	message []byte,
+	message []uint8,
 	retain bool,
 	timeout uint,
 	success func(goja.Value) (goja.Value, error),
@@ -85,7 +85,7 @@ func (c *client) Publish(
 func (c *client) publishSync(
 	topic string,
 	qos int,
-	message []byte,
+	message []uint8,
 	retain bool,
 	timeout uint,
 ) error {