diff --git a/nssa/src/public_transaction/encoding.rs b/nssa/src/public_transaction/encoding.rs
index 7f1ab62..3c004a0 100644
--- a/nssa/src/public_transaction/encoding.rs
+++ b/nssa/src/public_transaction/encoding.rs
@@ -92,9 +92,9 @@ impl Message {
 impl WitnessSet {
     pub(crate) fn to_bytes(&self) -> Vec<u8> {
         let mut bytes = Vec::new();
-        let size = self.signatures_and_public_keys.len() as u32;
+        let size = self.signatures_and_public_keys().len() as u32;
         bytes.extend_from_slice(&size.to_le_bytes());
-        for (signature, public_key) in &self.signatures_and_public_keys {
+        for (signature, public_key) in self.signatures_and_public_keys() {
             bytes.extend_from_slice(signature.to_bytes());
             bytes.extend_from_slice(public_key.to_bytes());
         }
diff --git a/nssa/src/public_transaction/transaction.rs b/nssa/src/public_transaction/transaction.rs
index 9315ba8..bd16644 100644
--- a/nssa/src/public_transaction/transaction.rs
+++ b/nssa/src/public_transaction/transaction.rs
@@ -37,7 +37,8 @@ impl PublicTransaction {
 
     pub(crate) fn signer_addresses(&self) -> Vec<Address> {
         self.witness_set
-            .iter_signatures()
+            .signatures_and_public_keys()
+            .iter()
             .map(|(_, public_key)| Address::from_public_key(public_key))
             .collect()
     }
@@ -115,7 +116,7 @@ impl PublicTransaction {
 }
 
 #[cfg(test)]
-mod tests {
+pub mod tests {
     use sha2::{Digest, digest::FixedOutput};
 
     use crate::{
diff --git a/nssa/src/public_transaction/witness_set.rs b/nssa/src/public_transaction/witness_set.rs
index 064887a..ae87080 100644
--- a/nssa/src/public_transaction/witness_set.rs
+++ b/nssa/src/public_transaction/witness_set.rs
@@ -2,7 +2,7 @@ use crate::{PrivateKey, PublicKey, Signature, public_transaction::Message};
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct WitnessSet {
-    pub(crate) signatures_and_public_keys: Vec<(Signature, PublicKey)>,
+    pub(super) signatures_and_public_keys: Vec<(Signature, PublicKey)>,
 }
 
 impl WitnessSet {
@@ -24,7 +24,7 @@ impl WitnessSet {
 
     pub fn is_valid_for(&self, message: &Message) -> bool {
         let message_bytes = message.to_bytes();
-        for (signature, public_key) in self.iter_signatures() {
+        for (signature, public_key) in self.signatures_and_public_keys() {
             if !signature.is_valid_for(&message_bytes, public_key) {
                 return false;
             }
@@ -32,7 +32,41 @@ impl WitnessSet {
         true
     }
 
-    pub fn iter_signatures(&self) -> impl Iterator<Item = &(Signature, PublicKey)> {
-        self.signatures_and_public_keys.iter()
+    pub fn signatures_and_public_keys(&self) -> &[(Signature, PublicKey)] {
+        &self.signatures_and_public_keys
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Address;
+
+    use super::*;
+
+    #[test]
+    fn test_for_message_constructor() {
+        let key1 = PrivateKey::try_new([1; 32]).unwrap();
+        let key2 = PrivateKey::try_new([2; 32]).unwrap();
+        let pubkey1 = PublicKey::new_from_private_key(&key1);
+        let pubkey2 = PublicKey::new_from_private_key(&key2);
+        let addr1 = Address::from_public_key(&pubkey1);
+        let addr2 = Address::from_public_key(&pubkey2);
+        let nonces = vec![1, 2];
+        let instruction = vec![1, 2, 3, 4];
+        let message = Message::try_new([0; 8], vec![addr1, addr2], nonces, instruction).unwrap();
+
+        let witness_set = WitnessSet::for_message(&message, &[&key1, &key2]);
+
+        assert_eq!(witness_set.signatures_and_public_keys.len(), 2);
+
+        let message_bytes = message.to_bytes();
+        for ((signature, public_key), expected_public_key) in witness_set
+            .signatures_and_public_keys
+            .into_iter()
+            .zip([pubkey1, pubkey2])
+        {
+            assert_eq!(public_key, expected_public_key);
+            assert!(signature.is_valid_for(&message_bytes, &expected_public_key));
+        }
     }
 }
diff --git a/sequencer_core/src/lib.rs b/sequencer_core/src/lib.rs
index 0f66b4a..b56b34cc 100644
--- a/sequencer_core/src/lib.rs
+++ b/sequencer_core/src/lib.rs
@@ -232,9 +232,15 @@ mod tests {
 
     #[test]
     fn test_start_different_intial_accounts_balances() {
-        let acc1_addr = vec![27, 132, 197, 86, 123, 18, 100, 64, 153, 93, 62, 213, 170, 186, 5, 101, 215, 30, 24, 52, 96, 72, 25, 255, 156, 23, 245, 233, 213, 221, 7, 143];
+        let acc1_addr = vec![
+            27, 132, 197, 86, 123, 18, 100, 64, 153, 93, 62, 213, 170, 186, 5, 101, 215, 30, 24,
+            52, 96, 72, 25, 255, 156, 23, 245, 233, 213, 221, 7, 143,
+        ];
 
-        let acc2_addr = vec![77, 75, 108, 209, 54, 16, 50, 202, 155, 210, 174, 185, 217, 0, 170, 77, 69, 217, 234, 216, 10, 201, 66, 51, 116, 196, 81, 167, 37, 77, 7, 102];
+        let acc2_addr = vec![
+            77, 75, 108, 209, 54, 16, 50, 202, 155, 210, 174, 185, 217, 0, 170, 77, 69, 217, 234,
+            216, 10, 201, 66, 51, 116, 196, 81, 167, 37, 77, 7, 102,
+        ];
 
         let initial_acc1 = AccountInitialData {
             addr: hex::encode(acc1_addr),