Use mockPersister

Use a mock persister when there's no need for either a local or remote
persister in a test. These tests do not need to validate that a
screenshot was saved.

tests/element_handle_test.go

@@ -2,13 +2,14 @@ package tests
 
 import (
 	"bytes"
+	"context"
 	_ "embed"
 	"fmt"
 	"image/png"
+	"io"
 	"testing"
 
 	"github.com/grafana/xk6-browser/common"
-	"github.com/grafana/xk6-browser/storage"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -344,6 +345,12 @@ func TestElementHandleQueryAll(t *testing.T) {
 	})
 }
 
+type mockPersister struct{}
+
+func (m *mockPersister) Persist(ctx context.Context, path string, data io.Reader) (err error) {
+	return nil
+}
+
 func TestElementHandleScreenshot(t *testing.T) {
 	t.Parallel()
 
@@ -375,11 +382,9 @@ func TestElementHandleScreenshot(t *testing.T) {
 	elem, err := p.Query("div")
 	require.NoError(t, err)
 
-	// TODO: Use a mock instead of a LocalFilePersister when there's no need to
-	//       persist files.
 	buf, err := elem.Screenshot(
 		common.NewElementHandleScreenshotOptions(elem.Timeout()),
-		&storage.LocalFilePersister{},
+		&mockPersister{},
 	)
 	require.NoError(t, err)
 

tests/page_test.go

@@ -19,7 +19,6 @@ import (
 	"github.com/grafana/xk6-browser/browser"
 	"github.com/grafana/xk6-browser/common"
 	"github.com/grafana/xk6-browser/k6ext/k6test"
-	"github.com/grafana/xk6-browser/storage"
 )
 
 type emulateMediaOpts struct {
@@ -476,9 +475,7 @@ func TestPageScreenshotFullpage(t *testing.T) {
 
 	opts := common.NewPageScreenshotOptions()
 	opts.FullPage = true
-	// TODO: Use a mock instead of a LocalFilePersister when there's no need to
-	//       persist files.
-	buf, err := p.Screenshot(opts, &storage.LocalFilePersister{})
+	buf, err := p.Screenshot(opts, &mockPersister{})
 	require.NoError(t, err)
 
 	reader := bytes.NewReader(buf)