cmz/tests/two_groups.rs

//! The basepoints map is keyed by group type, so two groups must be able
//! to coexist in one process.
//!
//! Before the key was `G`, `StaticTypeMap::call_once` was handed
//! `Box<dyn CMZbp>` — the same `TypeId` for every group — so the map held a
//! single shared slot. The second group's `cmz_group_init` was silently
//! ignored and the following `cmz_basepoints` read back the *first* group's
//! basepoints, failing the downcast and panicking.

use cmz::{cmz_basepoints, cmz_group_init};
use curve25519_dalek::ristretto::RistrettoPoint;
use group::Group;
use sha2::Sha512;

#[test]
fn two_groups_coexist() {
    let ristretto_a = RistrettoPoint::hash_from_bytes::<Sha512>(b"CMZ Generator A");
    let p256_a = p256::ProjectivePoint::generator() * p256::Scalar::from(42u64);

    cmz_group_init::<RistrettoPoint>(ristretto_a);
    cmz_group_init::<p256::ProjectivePoint>(p256_a);

    // Each group must read back its own basepoints, not the other's.
    assert_eq!(cmz_basepoints::<RistrettoPoint>().A(), ristretto_a);
    assert_eq!(cmz_basepoints::<RistrettoPoint>().B(), RistrettoPoint::generator());
    assert_eq!(cmz_basepoints::<p256::ProjectivePoint>().A(), p256_a);
    assert_eq!(
        cmz_basepoints::<p256::ProjectivePoint>().B(),
        p256::ProjectivePoint::generator()
    );

    // Re-initializing keeps the first value, per cmz_group_init's contract.
    cmz_group_init::<RistrettoPoint>(RistrettoPoint::generator());
    assert_eq!(cmz_basepoints::<RistrettoPoint>().A(), ristretto_a);
}