public void Returns_true_when_the_guids_can_be_valid()
        {
            var retriever = new GuidValueRetriever();

            retriever.IsAValidGuid("0").ShouldBeTrue();
            retriever.IsAValidGuid("{47B864A3-DEB9-4222-B7F8-F176F2E2CEFF}").ShouldBeTrue();
        }
        public void Returns_false_when_the_guids_contain_invalid_characters()
        {
            var retriever = new GuidValueRetriever();

            retriever.IsAValidGuid("z").ShouldBeFalse();
            retriever.IsAValidGuid("{9537F8CA-EB2B-4B8A-97D5-705778AAD1G5}").ShouldBeFalse();
        }
        public void Returns_false_when_the_guid_is_empty()
        {
            var retriever = new GuidValueRetriever();

            retriever.IsAValidGuid(string.Empty).ShouldBeFalse();
        }
        public void Returns_false_when_the_guid_is_null()
        {
            var retriever = new GuidValueRetriever();

            retriever.IsAValidGuid(null).ShouldBeFalse();
        }