public void IsValid_InvalidCharacter_ShouldBeFalse()
        {
            var result = new NorwegianSsnValidator().IsValid("x0123456789");

            result.Should().BeFalse();
        }
        public void IsValid_NullValue_ShouldBeFalse()
        {
            var result = new NorwegianSsnValidator().IsValid(null);

            result.Should().BeFalse();
        }
        public void IsValid_InvalidLength_ShouldBeFalse()
        {
            var result = new NorwegianSsnValidator().IsValid("9");

            result.Should().BeFalse();
        }