public int GetNumbersCountRecursive_ParametersAreValid_ReturnsCharsCount(string str)
 {
     // Act
     return(DoWhileMethods.GetDigitCountRecursive(str));
 }
 public void GetNumbersCountRecursive_StrIsNull_ThrowsException()
 {
     // Act
     Assert.Throws <ArgumentNullException>(() => DoWhileMethods.GetDigitCountRecursive(null));
 }