public void IsAcceptableSigningCertificate_WhenPackageRegistrationIsNull_Throws()
            {
                var exception = Assert.Throws <ArgumentNullException>(
                    () => PackageRegistrationExtensions.IsAcceptableSigningCertificate(packageRegistration: null, thumbprint: "a"));

                Assert.Equal("packageRegistration", exception.ParamName);
            }
            public void IsSigningAllowed_WhenPackageRegistrationIsNull_Throws()
            {
                var exception = Assert.Throws <ArgumentNullException>(
                    () => PackageRegistrationExtensions.IsSigningRequired(packageRegistration: null));

                Assert.Equal("packageRegistration", exception.ParamName);
            }