public void EgnShouldBeInvalid(string egn)
        {
            var attribute = new EgnValidationAttribute();

            var result = attribute.IsValid(egn);

            Assert.False(result);
        }
        public void Egn1234567890ShouldBeValid()
        {
            // Arrange
            var validationAttribute = new EgnValidationAttribute();

            // Act
            var isValid = validationAttribute.IsValid("1234567890");

            // Assert
            Assert.True(isValid);
        }