public void ConvertToExcelTest()
{
var converter = new TimeSpanConverter();
var typeConverterOptions = new TypeConverterOptions {
CultureInfo = CultureInfo.CurrentCulture
};
var dateTime = DateTime.Now;
var timeSpan = new TimeSpan(dateTime.Hour, dateTime.Minute, dateTime.Second, dateTime.Millisecond);
// Valid conversions.
Assert.AreEqual(timeSpan.ToString(), converter.ConvertToExcel(typeConverterOptions, timeSpan));
// Invalid conversions.
Assert.AreEqual("1", converter.ConvertToExcel(typeConverterOptions, 1));
Assert.AreEqual(null, converter.ConvertToExcel(typeConverterOptions, null));
}