diff --git a/src/dns.rs b/src/dns.rs
index c2c14e0..3fbcd0b 100644
--- a/src/dns.rs
+++ b/src/dns.rs
@@ -246,14 +246,9 @@ impl RequestHandler for IronDnsHandler {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use iroh::SecretKey;
+    use crate::test_utils::test_endpoint_id;
     use std::str::FromStr;
 
-    fn test_endpoint_id(seed: u8) -> EndpointId {
-        let secret = SecretKey::from_bytes(&[seed; 32]);
-        secret.public()
-    }
-
     #[test]
     fn test_dns_resolver_new() {
         let registry = Arc::new(Registry::new());
diff --git a/src/lib.rs b/src/lib.rs
index 3833f6d..5340c1f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,7 @@ pub mod keys;
 pub mod mapping;
 pub mod node;
 pub mod packet;
+pub mod test_utils;
 pub mod protocol;
 pub mod tun;
 
diff --git a/src/mapping.rs b/src/mapping.rs
index c51cad2..bf1113c 100644
--- a/src/mapping.rs
+++ b/src/mapping.rs
@@ -274,13 +274,7 @@ impl Default for Registry {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use iroh::SecretKey;
-
-    /// Helper to create a test EndpointId from a seed value
-    fn test_endpoint_id(seed: u8) -> EndpointId {
-        let secret = SecretKey::from_bytes(&[seed; 32]);
-        secret.public()
-    }
+    use crate::test_utils::test_endpoint_id;
 
     #[test]
     fn test_registry_new() {
diff --git a/src/protocol.rs b/src/protocol.rs
index ed48587..c2b0ae9 100644
--- a/src/protocol.rs
+++ b/src/protocol.rs
@@ -383,11 +383,7 @@ mod tests {
     use iroh::endpoint::presets::N0;
     use std::net::Ipv6Addr;
 
-    /// Helper to create test EndpointIds
-    fn test_endpoint_id(seed: u8) -> EndpointId {
-        let secret = SecretKey::from_bytes(&[seed; 32]);
-        secret.public()
-    }
+    use crate::test_utils::test_endpoint_id;
 
     /// Helper to create a minimal valid IPv6 packet
     fn create_ipv6_packet(src: Ipv6Addr, dst: Ipv6Addr, payload_size: usize) -> Vec<u8> {
diff --git a/src/test_utils.rs b/src/test_utils.rs
new file mode 100644
index 0000000..345b0e3
--- /dev/null
+++ b/src/test_utils.rs
@@ -0,0 +1,9 @@
+use iroh::{EndpointId, SecretKey};
+
+/// Create a test `EndpointId` from a seed byte.
+/// The same seed always produces the same `EndpointId`,
+/// making tests deterministic and reproducible.
+pub fn test_endpoint_id(seed: u8) -> EndpointId {
+    let secret = SecretKey::from_bytes(&[seed; 32]);
+    secret.public()
+}
diff --git a/src/tun.rs b/src/tun.rs
index fa342a4..3195dbf 100644
--- a/src/tun.rs
+++ b/src/tun.rs
@@ -484,12 +484,7 @@ impl TunInterface {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use iroh::SecretKey;
-
-    fn test_endpoint_id(seed: u8) -> iroh::EndpointId {
-        let secret = SecretKey::from_bytes(&[seed; 32]);
-        secret.public()
-    }
+    use crate::test_utils::test_endpoint_id;
 
     #[test]
     fn test_tun_interface_new() {
diff --git a/tests/integration.rs b/tests/integration.rs
index c743e42..a1d9e8e 100644
--- a/tests/integration.rs
+++ b/tests/integration.rs
@@ -16,11 +16,7 @@ use std::sync::Arc;
 use tempfile::TempDir;
 use tokio::sync::mpsc;
 
-/// Helper to create test EndpointIds
-fn test_endpoint_id(seed: u8) -> EndpointId {
-    let secret = SecretKey::from_bytes(&[seed; 32]);
-    secret.public()
-}
+use iron::test_utils::test_endpoint_id;
 
 /// Test that Registry provides consistent mappings across all components
 #[tokio::test]