public void Cols_to_string_should_end_with_tab()
{
//arrange
var sut = new CSVReaderWriter();
string[] cols = { "col1", "col2" };
//act
sut.Open(TestInputFile, CSVReaderWriter.Mode.Read);
var result = sut.ColToString(cols);
//assert
Assert.That(result, Is.EqualTo("col1\tcol2"));
//clean up
sut.Close();
}