public void Ctor_Xtext_CorrectData()
        {
            //arrange, act
            ExternalLine sut = new Xtext("blahblah");

            //assert
            sut.Should().BeOfType <Xtext>();
            sut.Type.Should().Be(ExternalLineType.Xtext);
            sut.Excerpt.Should().Be("blahblah");
            sut.ClstrNo.Should().Be(0);
            sut.Text.Should().Be("blahblah");
            sut.Items.Should().BeNull();
        }