public void EnsureBasicLayout()
{
widget.Arrange(new Rectangle(10, 20, 200, 100));
measureCalled.Called.Should().BeTrue();
measureCalled.Argument.Should().Be(new Size(200, 100));
arrangeCalled.Called.Should().BeTrue();
arrangeCalled.Argument.Should().Be(new Rectangle(10, 20, 200, 100));
widget.DesiredSize.Should().Be(new Size(200, 100));
widget.LayoutRect.Should().Be(new Rectangle(10, 20, 200, 100));
}