public void find_by_issuer()
        {
            var issuers = new SamlCertificate[]
            {
                new SamlCertificate{Issuer = "foo:bar1"}, 
                new SamlCertificate{Issuer = "foo:bar2"}, 
                new SamlCertificate{Issuer = "foo:bar3"} 
            };

            var repository = new BasicSamlCertificateRepository(issuers);
            repository.Find(issuers[0].Issuer).ShouldBeTheSameAs(issuers[0]);
            repository.Find(issuers[1].Issuer).ShouldBeTheSameAs(issuers[1]);
            repository.Find(issuers[2].Issuer).ShouldBeTheSameAs(issuers[2]);
        }