public void IsLongDigitalStringDigigtsOnly()
        {
            var numberService = new NumberService();

            var res = numberService.IsDigitsOnly("12342342342343242342334234324234312");

            Assert.IsTrue(res);
        }
        public void IsZeroLengthStringDigigtsOnly()
        {
            var numberService = new NumberService();

            var res = numberService.IsDigitsOnly("");

            Assert.IsFalse(res);
        }
        public void IsLongNonDigitalStringDigigtsOnly()
        {
            var numberService = new NumberService();

            var res = numberService.IsDigitsOnly("123324324234234234234234123basdasdas12312312312312312312");

            Assert.IsFalse(res);
        }
        public void IsNullDigigtsOnly()
        {
            var numberService = new NumberService();

            var res = numberService.IsDigitsOnly(null);

            Assert.IsFalse(res);
        }
        public void IsShortNonDigitalStringDigigtsOnly()
        {
            var numberService = new NumberService();

            var res = numberService.IsDigitsOnly("123a123");

            Assert.IsFalse(res);
        }