public void AddCenteredParagraph_Valid()
{
List <int[]> list = new List <int[]>();
list.Add(new int[] { 1, 2 });
list.Add(new int[] { 3, 4 });
list.Add(new int[] { 5, 6 });
Shape polygon = PowerpointHelper.CreatePolygon(list);
int oldNbParagraph = polygon.Descendants <D.Paragraph>().Count();
PowerpointHelper.AddCenteredParagraph(polygon, "text");
var errors = validator.Validate(polygon);
Assert.IsTrue(errors.Count() == 0);
Assert.IsTrue(polygon.Descendants <D.Paragraph>().Count() - oldNbParagraph == 1);
}