public void InsertSpanTest() { string s = " That is text."; Span span = new Span() { Text = s }; var newText = text.InsertSpan(1, span); Assert.AreEqual(newText[1].Equals(span), true); Assert.AreEqual(newText.Length, text.Length + 1); Assert.AreEqual(text.AnySpanReferenceEquals(newText), false); }