Use custom error for object overflow warning

Resolves #130 (comment)

Author: Ivan Mirić

common/frame_session.go

@@ -23,6 +23,7 @@ package common
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strings"
 	"sync"
@@ -479,8 +480,13 @@ func (fs *FrameSession) onConsoleAPICalled(event *runtime.EventConsoleAPICalled)
 	for _, robj := range event.Args {
 		i, err := parseRemoteObject(robj, l)
 		if err != nil {
-			// If this throws it's a bug :)
-			k6Throw(fs.ctx, "unable to parse remote object value: %w", err)
+			var oe *objectOverflowError
+			if errors.As(err, &oe) {
+				l.Warn(err)
+			} else {
+				// If this throws it's a bug :)
+				k6Throw(fs.ctx, "unable to parse remote object value: %w", err)
+			}
 		}
 		parsedObjects = append(parsedObjects, i)
 	}

common/remote_object.go

@@ -33,10 +33,18 @@ import (
 	k6common "go.k6.io/k6/js/common"
 )
 
+type objectOverflowError struct{}
+
+// Error returns the description of the overflow error.
+func (*objectOverflowError) Error() string {
+	return "object is too large and will be parsed partially"
+}
+
 func parseRemoteObjectPreview(op *cdpruntime.ObjectPreview, logger *logrus.Entry) (map[string]interface{}, error) {
 	obj := make(map[string]interface{})
+	var err error
 	if op.Overflow {
-		logger.Warn("object will be parsed partially")
+		err = &objectOverflowError{}
 	}
 
 	for _, p := range op.Properties {
@@ -48,7 +56,7 @@ func parseRemoteObjectPreview(op *cdpruntime.ObjectPreview, logger *logrus.Entry
 		obj[p.Name] = val
 	}
 
-	return obj, nil
+	return obj, err
 }
 
 func parseRemoteObjectValue(

common/remote_object_test.go

@@ -28,7 +28,6 @@ import (
 
 	"github.com/chromedp/cdproto/runtime"
 	"github.com/dop251/goja"
-	"github.com/grafana/xk6-browser/testutils"
 	"github.com/mailru/easyjson"
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
@@ -192,6 +191,7 @@ func TestParseRemoteObject(t *testing.T) {
 		preview  *runtime.ObjectPreview
 		value    string
 		expected map[string]interface{}
+		expErr   error
 	}{
 		{
 			name: "most_types",
@@ -236,6 +236,7 @@ func TestParseRemoteObject(t *testing.T) {
 			name:     "overflow",
 			preview:  &runtime.ObjectPreview{Overflow: true},
 			expected: map[string]interface{}{},
+			expErr:   &objectOverflowError{},
 		},
 	}
 
@@ -249,14 +250,13 @@ func TestParseRemoteObject(t *testing.T) {
 				Value:    easyjson.RawMessage(tc.value),
 			}
 			lg := logrus.New()
-			logHook := testutils.LogHook(lg)
 			logger := NewLogger(ctx, lg, false, nil)
 			val, err := parseRemoteObject(remoteObject, logger.log.WithContext(ctx))
-			require.NoError(t, err)
 			assert.Equal(t, tc.expected, val)
-
-			if tc.name == "overflow" {
-				assert.True(t, logHook.Contains("object will be parsed partially"))
+			if tc.expErr != nil {
+				assert.ErrorAs(t, err, &tc.expErr)
+			} else {
+				assert.NoError(t, err)
 			}
 		})
 	}