message: include test nullifying numbers with subtraction
diff: @@ -6,7 +6,10 @@ use crate::circuits::{
  };
  use ark_ec::AffineCurve;
  use ark_ff::{One, Zero};
  -use mina_curves::pasta::{pallas, vesta::Vesta};
  +use mina_curves::pasta::{
  + pallas::{self, Pallas},
  + vesta::Vesta,
  +};
  use num_bigint::BigUint;
  use num_traits::FromPrimitive;
  use o1_utils::{
  @@ -269,6 +272,33 @@ fn test_zero_minus_one() {
  assert_eq!(witness[2][17], *right_input.hi());
  }
  +#[test]
  +// test 1 - 1 where (-1) is in the foreign field
  +fn test_one_minus_one() {
  + let cs = create_test_constraint_system();
  +
  + let foreign_modulus = ForeignElement::<PallasField, 3>::new_from_be(FOREIGN_MOD);
  +
  + // big uint of the number 1
  + let big_one = BigUint::from_u32(1).unwrap();
  +
  + let left_input = ForeignElement::<PallasField, 3>::new_from_big(big_one.clone());
  + let right_input = ForeignElement::<PallasField, 3>::new_from_neg(big_one);
  +
  + let witness = create_witness(left_input, right_input, foreign_modulus);
  +
  + for row in 0..=17 {
  + assert_eq!(
  + cs.gates[row].verify::<Vesta>(row, &witness, &cs, &[]),
  + Ok(())
  + );
  + }
  +
  + assert_eq!(witness[0][17], PallasField::zero());
  + assert_eq!(witness[1][17], PallasField::zero());
  + assert_eq!(witness[2][17], PallasField::zero());
  +}
  +
  #[test]
  // test -1-1 where (-1) is in the foreign field
  fn test_minus_minus() {
  