public static void Format_ThrowsFormatException()
{
IFormatProvider fp = new CustomerFormatProvider();
Assert.Throws <FormatException>(() => string.Format(fp, "{0:w}", customer));
}
public static string Format_PositiveTest(Customer customer, string format)
{
IFormatProvider fp = new CustomerFormatProvider();
return(string.Format(fp, format, customer));
}