public void TestAdd()
        {
            // Arrange
            var entity = new FakeModel {
                FirstProperty = "fake4", SecondProperty = 4
            };

            var index = 0;

            ReaderMock.Setup(reader => reader.ReadLine())
            .Returns(() => file[index++]);
            ReaderMock.SetupGet(reader => reader.EndOfStream)
            .Returns(() => index >= file.Length ? true : false);

            var expectedEntityToCsv = EntityToCSV(file.Count() + 1, entity.FirstProperty, entity.SecondProperty);

            // Act
            TestedDataLayer.Add(entity);

            // Assert
            WriterMock.Verify(writer => writer.WriteLine(expectedEntityToCsv), Times.Once);
        }