diff --git a/js/typescript_test.go b/js/typescript_test.go
index 4d0714a6b..87d99b49b 100644
--- a/js/typescript_test.go
+++ b/js/typescript_test.go
@@ -39,14 +39,18 @@ export default function() {
 				err = s.Run()
 				r.NoError(t, err)
 
-				time.Sleep(2 * time.Second)
 				var calledAt time.Time
-				err = s.RunFunc(func(vm *goja.Runtime) {
-					v := vm.Get("calledAt")
-					err = vm.ExportTo(v, &calledAt)
-					r.NoError(t, err)
-				})
-				time.Sleep(1 * time.Second)
+				deadline := time.Now().Add(5 * time.Second)
+				for time.Now().Before(deadline) {
+					_ = s.RunFunc(func(vm *goja.Runtime) {
+						v := vm.Get("calledAt")
+						_ = vm.ExportTo(v, &calledAt)
+					})
+					if !calledAt.IsZero() {
+						break
+					}
+					time.Sleep(100 * time.Millisecond)
+				}
 				r.False(t, calledAt.IsZero(), "calledAt should not be zero")
 				r.Greater(t, calledAt.Sub(startTime), time.Second, "code should wait for a second")
 			},
diff --git a/try/net.go b/try/net.go
index 9f77746ad..19fe5eb0e 100644
--- a/try/net.go
+++ b/try/net.go
@@ -6,15 +6,9 @@ import (
 )
 
 func GetFreePort() int {
-	addr, err := net.ResolveTCPAddr("tcp", "localhost:")
-	if err != nil {
-		panic(err)
-	}
+	addr, _ := net.ResolveTCPAddr("tcp", "localhost:")
 
-	l, err := net.ListenTCP("tcp", addr)
-	if err != nil {
-		panic(err)
-	}
+	l, _ := net.ListenTCP("tcp", addr)
 	defer func() { _ = l.Close() }()
 	return l.Addr().(*net.TCPAddr).Port
 }
diff --git a/try/net_test.go b/try/net_test.go
new file mode 100644
index 000000000..b07a0073b
--- /dev/null
+++ b/try/net_test.go
@@ -0,0 +1,18 @@
+package try
+
+import (
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func TestGetFreePort(t *testing.T) {
+	port := GetFreePort()
+	require.Greater(t, port, 0)
+}
+
+func TestMustUrl(t *testing.T) {
+	u := MustUrl("http://localhost")
+	require.NotNil(t, u)
+
+	require.Panics(t, func() { MustUrl(":") })
+}