move the poseidon_config function outside from tests

move the poseidon_config function outside from tests, since when
externally using this lib usually the user will also use the
poseidon_config helper to generate the poseidon config to be used in the
signature

src/constraints.rs

@@ -51,18 +51,17 @@ where
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use crate::ed_on_bn254_twist::{
-        constraints::EdwardsVar as GVar, BaseField as Fq, EdwardsConfig, EdwardsProjective as G,
-        ScalarField as Fr,
-    };
     use ark_ff::PrimeField;
     use ark_r1cs_std::{alloc::AllocVar, eq::EqGadget, fields::nonnative::NonNativeFieldVar};
     use ark_relations::r1cs::ConstraintSystem;
     use rand_core::OsRng;
 
-    use crate::test::poseidon_config;
-    use crate::SigningKey;
+    use super::*;
+    use crate::ed_on_bn254_twist::{
+        constraints::EdwardsVar as GVar, BaseField as Fq, EdwardsConfig, EdwardsProjective as G,
+        ScalarField as Fr,
+    };
+    use crate::{poseidon_config, SigningKey};
 
     #[test]
     fn gadget_verify() {

src/lib.rs

@@ -1,3 +1,8 @@
+use ark_ff::PrimeField;
+use digest::Digest;
+impl ark_std::error::Error for Error {}
+use ark_crypto_primitives::sponge::poseidon::{find_poseidon_ark_and_mds, PoseidonConfig};
+
 pub mod ed_on_bn254_twist;
 pub mod eddsa;
 pub mod signature;
@@ -5,8 +10,6 @@ pub mod signature;
 #[cfg(feature = "r1cs")]
 pub mod constraints;
 
-use ark_ff::PrimeField;
-use digest::Digest;
 pub use eddsa::*;
 
 pub(crate) fn from_digest<F: PrimeField, D: Digest>(digest: D) -> F {
@@ -29,35 +32,33 @@ impl core::fmt::Display for Error {
     }
 }
 
-impl ark_std::error::Error for Error {}
+/// Generates poseidon constants and returns the config
+pub fn poseidon_config<F: PrimeField>(
+    rate: usize,
+    full_rounds: usize,
+    partial_rounds: usize,
+) -> PoseidonConfig<F> {
+    let prime_bits = F::MODULUS_BIT_SIZE as u64;
+    let (ark, mds) = find_poseidon_ark_and_mds(
+        prime_bits,
+        rate,
+        full_rounds as u64,
+        partial_rounds as u64,
+        0,
+    );
+    PoseidonConfig::new(full_rounds, partial_rounds, 5, mds, ark, rate, 1)
+}
 
 #[cfg(test)]
 mod test {
-
-    use crate::SigningKey;
-    use ark_crypto_primitives::sponge::poseidon::{find_poseidon_ark_and_mds, PoseidonConfig};
     use ark_crypto_primitives::sponge::Absorb;
     use ark_ec::twisted_edwards::TECurveConfig;
     use ark_ff::PrimeField;
     use digest::Digest;
     use rand_core::OsRng;
 
-    /// Generates poseidon constants and returns the config
-    pub fn poseidon_config<F: PrimeField>(
-        rate: usize,
-        full_rounds: usize,
-        partial_rounds: usize,
-    ) -> PoseidonConfig<F> {
-        let prime_bits = F::MODULUS_BIT_SIZE as u64;
-        let (ark, mds) = find_poseidon_ark_and_mds(
-            prime_bits,
-            rate,
-            full_rounds as u64,
-            partial_rounds as u64,
-            0,
-        );
-        PoseidonConfig::new(full_rounds, partial_rounds, 5, mds, ark, rate, 1)
-    }
+    use super::poseidon_config;
+    use crate::SigningKey;
 
     fn run_test<TE: TECurveConfig + Clone, D: Digest>()
     where