public void Sign_Should_Throw_Exception_When_PrivateKey_Is_Null()
{
var publicKey = ECDsa.Create();
var alg = new ES256Algorithm(publicKey);
var bytesToSign = Array.Empty <byte>();
Action action =
() => alg.Sign(null, bytesToSign);
action.Should()
.Throw <InvalidOperationException>("because asymmetric algorithm cannot sign data without private key");
}
