public void WithNotGuid()
        {
            // arrange
            var value = "this is a string";
            var attrib = new GuidKeyValidatorAttribute();

            // act
            var result = attrib.IsValid(value);

            // assert
            Assert.That(result, Is.False);
        }
        public void WithEmptyGuid()
        {
            // arrange
            var value = Guid.Empty;
            var attrib = new GuidKeyValidatorAttribute();

            // act
            var result = attrib.IsValid(value);

            // assert
            Assert.That(result, Is.False);
        }
        public void WithNullGuid()
        {
            // arrange
            object value = null;
            var attrib = new GuidKeyValidatorAttribute();

            // act
            var result = attrib.IsValid(value);

            // assert
            Assert.That(result, Is.False);
        }