public void Save(IEnumerable <Slide> slides)
        {
            var slideWriter = new SlideWriter();
            var outputLines = slideWriter.Format(slides);

            File.WriteAllLines(this._outputFilePath, outputLines);
        }
        public void Write()
        {
            var writer = new SlideWriter();

            var slides = new List <Slide>
            {
                new Slide
                {
                    Photos = new List <Photo> {
                        new Photo {
                            Id = 0
                        }
                    }
                },
                new Slide
                {
                    Photos = new List <Photo> {
                        new Photo {
                            Id = 3
                        }
                    }
                },
                new Slide
                {
                    Photos = new List <Photo> {
                        new Photo {
                            Id = 1
                        }, new Photo {
                            Id = 2
                        }
                    }
                }
            };

            var lines = writer.Format(slides).ToList();

            Assert.Equal(4, lines.Count());

            Assert.Equal("3", lines[0]);
            Assert.Equal("0", lines[1]);
            Assert.Equal("3", lines[2]);
            Assert.Equal("1 2", lines[3]);
        }