public void ParagraphsAdd_AddsANewTextParagraphAtTheEndOfTheTextBoxAndReturnsAddedParagraph_WhenParagraphIsAddedAfterTextBoxContentChanged() { IPresentation presentation = SCPresentation.Open(Properties.Resources._001, true); IAutoShape autoShape = (IAutoShape)presentation.Slides[0].Shapes.First(sp => sp.Id == 3); ITextBox textBox = autoShape.TextBox; IParagraphCollection paragraphs = textBox.Paragraphs; IParagraph paragraph = textBox.Paragraphs.First(); textBox.Text = "A new text"; // Act IParagraph newParagraph = paragraphs.Add(); // Assert newParagraph.Should().NotBeNull(); }