Fix ws.Set(Timeout/Interval) panicking on float values (#1608)

The issue is connected to dop251/goja#190 in the
sense that instead of the float to int conversation to result in either
error or a clamped float value, it results in a 0 int value which panics
the stdlib time package.

Changing the parameter for the timeout/interval to float both makes it
possible to take values such as 0.5, meaning half a ms, and also checks
if the value is positive so we can be certain that it won't panic k6.
If not this results in an exception in the script.

Co-authored-by: Ivan Mirić <ivan@loadimpact.com>

js/modules/k6/ws/ws.go

@@ -24,6 +24,7 @@ import (
 	"context"
 	"crypto/tls"
 	"errors"
+	"fmt"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -380,12 +381,18 @@ func (s *Socket) trackPong(pingID string) {
 	})
 }
 
-func (s *Socket) SetTimeout(fn goja.Callable, timeoutMs int) {
+// SetTimeout executes the provided function inside the socket's event loop after at least the provided
+// timeout, which is in ms, has elapsed
+func (s *Socket) SetTimeout(fn goja.Callable, timeoutMs float64) error {
 	// Starts a goroutine, blocks once on the timeout and pushes the callable
 	// back to the main loop through the scheduled channel
+	d := time.Duration(timeoutMs * float64(time.Millisecond))
+	if d <= 0 {
+		return fmt.Errorf("setTimeout requires a >0 timeout parameter, received %.2f", timeoutMs)
+	}
 	go func() {
 		select {
-		case <-time.After(time.Duration(timeoutMs) * time.Millisecond):
+		case <-time.After(d):
 			select {
 			case s.scheduled <- fn:
 			case <-s.done:
@@ -396,11 +403,19 @@ func (s *Socket) SetTimeout(fn goja.Callable, timeoutMs int) {
 			return
 		}
 	}()
+
+	return nil
 }
 
-func (s *Socket) SetInterval(fn goja.Callable, intervalMs int) {
+// SetInterval executes the provided function inside the socket's event loop each interval time, which is
+// in ms
+func (s *Socket) SetInterval(fn goja.Callable, intervalMs float64) error {
 	// Starts a goroutine, blocks forever on the ticker and pushes the callable
 	// back to the main loop through the scheduled channel
+	d := time.Duration(intervalMs * float64(time.Millisecond))
+	if d <= 0 {
+		return fmt.Errorf("setInterval requires a >0 timeout parameter, received %.2f", intervalMs)
+	}
 	go func() {
 		ticker := time.NewTicker(time.Duration(intervalMs) * time.Millisecond)
 		defer ticker.Stop()
@@ -419,6 +434,8 @@ func (s *Socket) SetInterval(fn goja.Callable, intervalMs int) {
 			}
 		}
 	}()
+
+	return nil
 }
 
 func (s *Socket) Close(args ...goja.Value) {

js/modules/k6/ws/ws_test.go

@@ -32,6 +32,7 @@ import (
 	"github.com/dop251/goja"
 	"github.com/gorilla/websocket"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/loadimpact/k6/js/common"
 	"github.com/loadimpact/k6/lib"
@@ -87,7 +88,7 @@ func assertMetricEmitted(t *testing.T, metric *stats.Metric, sampleContainers []
 }
 
 func TestSession(t *testing.T) {
-	//TODO: split and paralelize tests
+	// TODO: split and paralelize tests
 	t.Parallel()
 	tb := httpmultibin.NewHTTPMultiBin(t)
 	defer tb.Cleanup()
@@ -193,6 +194,19 @@ func TestSession(t *testing.T) {
 		assert.NoError(t, err)
 	})
 	assertSessionMetricsEmitted(t, stats.GetBufferedSamples(samples), "", sr("WSBIN_URL/ws-echo"), 101, "")
+	t.Run("bad interval", func(t *testing.T) {
+		_, err := common.RunString(rt, sr(`
+		var counter = 0;
+		var res = ws.connect("WSBIN_URL/ws-echo", function(socket){
+			socket.setInterval(function () {
+				counter += 1;
+				if (counter > 2) { socket.close(); }
+			}, -1.23);
+		});
+		`))
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "setInterval requires a >0 timeout parameter, received -1.23 ")
+	})
 
 	t.Run("timeout", func(t *testing.T) {
 		_, err := common.RunString(rt, sr(`
@@ -210,6 +224,21 @@ func TestSession(t *testing.T) {
 		`))
 		assert.NoError(t, err)
 	})
+
+	t.Run("bad timeout", func(t *testing.T) {
+		_, err := common.RunString(rt, sr(`
+		var start = new Date().getTime();
+		var ellapsed = new Date().getTime() - start;
+		var res = ws.connect("WSBIN_URL/ws-echo", function(socket){
+			socket.setTimeout(function () {
+				ellapsed = new Date().getTime() - start;
+				socket.close();
+			}, 0);
+		});
+		`))
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "setTimeout requires a >0 timeout parameter, received 0.00 ")
+	})
 	assertSessionMetricsEmitted(t, stats.GetBufferedSamples(samples), "", sr("WSBIN_URL/ws-echo"), 101, "")
 
 	t.Run("ping", func(t *testing.T) {
@@ -438,7 +467,7 @@ func TestSystemTags(t *testing.T) {
 	rt := goja.New()
 	rt.SetFieldNameMapper(common.FieldNameMapper{})
 
-	//TODO: test for actual tag values after removing the dependency on the
+	// TODO: test for actual tag values after removing the dependency on the
 	// external service demos.kaazing.com (https://github.com/loadimpact/k6/issues/537)
 	testedSystemTags := []string{"group", "status", "subproto", "url", "ip"}