You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: util_test.go
    path of file: ./repos/fyne/internal/driver
    
    the code of the file until where you have to start completion: package driver_test

import (
	"image/color"
	"testing"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/canvas"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/internal/driver"
	internal_widget "f
    
func TestReverseWalkVisibleObjectTree_Clip(t *testing.T) {
	rect := canvas.NewRectangle(color.White)
	rect.SetMinSize(fyne.NewSize(100, 100))
	child := canvas.NewRectangle(color.Black)
	base := container.NewGridWithColumns(1,
		rect,
		internal_widget.NewScroll(child),
		container.NewGridWithColumns(2,
			canvas.NewCircle(color.White),
			canvas.NewCircle(color.White),
			canvas.NewCircle(color.White),
			&scrollable{},
		),
	)

	// We are not in a window. Resize the container to a default size.
	base.Resize(base.MinSize())

	var scClipPos, scrollableClipPos fyne.Position
	var scClipSize, scrollableClipSize fyne.Size

	driver.ReverseWalkVisibleObjectTree(base, func(object fyne.CanvasObject, position fyne.Position, clippingPos fyne.Position, clippingSize fyne.Size) bool {
		if _, ok := object.(*internal_widget.Scroll); ok {
			scClipPos = clippingPos
			scClipSize = clippingSize
		} else if _, ok = object.(fyne.Scrollable); ok {
			scrollableClipPos = clippingPos
			scrollableClipSize = clippingSize
		}
		return false
	}, nil)

	// layout:
	// +-------------------------------+
	// | 0,0: rect 100x100             |
	// +-------------------------------+
	// |            padding            |
	// +-------------------------------+
	// | 0,104: scroller 100x100       |
	// +-------------------------------+
	// |            padding            |
	// +--------------+-+--------------+
	// | circle 48x48 |p| circle 48x48 |
	// +--------------+-+--------------+
	// |            padding            |
	// +--------------+-+--------------+
	// | circle 48x48 |p| scrollable   |
	// +--------------+-+--------------+
	assert.Equal(t, fyne.NewPos(0, 104), scClipPos)
	assert.Equal(t, fyne.NewSize(100, 100), scClipSize)
	assert.Equal(t, fyne.NewPos(52, 260), scrollableClipPos)
	assert.Equal(t, fyne.NewSize(48, 48), scrollableClipSize)
}