refactor: find_free_port has preferred port

crates/pop-cli/src/commands/up/contract.rs

@@ -435,7 +435,7 @@ mod tests {
 	}
 
 	async fn start_test_environment() -> anyhow::Result<(Child, u16, TempDir)> {
-		let random_port = find_free_port();
+		let random_port = find_free_port(None);
 		let temp_dir = new_environment("testing")?;
 		let current_dir = env::current_dir().expect("Failed to get current directory");
 		mock_build_process(

crates/pop-cli/src/common/wallet.rs

@@ -20,8 +20,8 @@ pub async fn request_signature(call_data: Vec<u8>, rpc: String) -> anyhow::Resul
 	let ui = FrontendFromString::new(include_str!("../assets/index.html").to_string());
 
 	let transaction_data = TransactionData::new(rpc, call_data);
-	// Starts server with random port.
-	let mut wallet = WalletIntegrationManager::new(ui, transaction_data, None);
+	// Starts server with port 9090.
+	let mut wallet = WalletIntegrationManager::new(ui, transaction_data, Some(9090));
 	let url = wallet.server_url.clone();
 	log::step(format!("Wallet signing portal started at http://{url}."))?;
 

crates/pop-cli/src/wallet_integration.rs

@@ -73,9 +73,9 @@ impl WalletIntegrationManager {
 	pub fn new<F: Frontend>(
 		frontend: F,
 		payload: TransactionData,
-		maybe_port: Option<String>,
+		maybe_port: Option<u16>,
 	) -> Self {
-		let port = if let Some(port) = maybe_port { port } else { find_free_port().to_string() };
+		let port = if let Some(port) = maybe_port { port } else { find_free_port(maybe_port) };
 		Self::new_with_address(frontend, payload, format!("127.0.0.1:{}", port))
 	}
 
@@ -284,10 +284,9 @@ mod tests {
 	#[tokio::test]
 	async fn new_works() {
 		let frontend = FrontendFromString::new(TEST_HTML.to_string());
-		let mut wim =
-			WalletIntegrationManager::new(frontend, default_payload(), Some("9090".to_string()));
+		let mut wim = WalletIntegrationManager::new(frontend, default_payload(), Some(9190));
 
-		assert_eq!(wim.server_url, "127.0.0.1:9090");
+		assert_eq!(wim.server_url, "127.0.0.1:9190");
 		assert_eq!(wim.is_running(), true);
 		assert!(wim.state.lock().await.shutdown_tx.is_some());
 		assert!(wim.state.lock().await.signed_payload.is_none());

crates/pop-cli/tests/contract.rs

@@ -51,7 +51,7 @@ impl TransactionData {
 async fn contract_lifecycle() -> Result<()> {
 	const WALLET_INT_URI: &str = "http://127.0.0.1:9090";
 	const WAIT_SECS: u64 = 240;
-	let endpoint_port = find_free_port();
+	let endpoint_port = find_free_port(None);
 	let default_endpoint: &str = &format!("ws://127.0.0.1:{}", endpoint_port);
 	let temp = tempfile::tempdir().unwrap();
 	let temp_dir = temp.path();

crates/pop-cli/tests/parachain.rs

@@ -95,7 +95,7 @@ async fn parachain_lifecycle() -> Result<()> {
 	// Overwrite the config file to manually set the port to test pop call parachain.
 	let network_toml_path = temp_parachain_dir.join("network.toml");
 	fs::create_dir_all(&temp_parachain_dir)?;
-	let random_port = find_free_port();
+	let random_port = find_free_port(None);
 	let localhost_url = format!("ws://127.0.0.1:{}", random_port);
 	fs::write(
 		&network_toml_path,

crates/pop-common/src/lib.rs

@@ -64,12 +64,20 @@ pub fn target() -> Result<&'static str, Error> {
 	Err(Error::UnsupportedPlatform { arch: ARCH, os: OS })
 }
 
-/// Finds an available port by binding to port 0 and retrieving the assigned port.
-pub fn find_free_port() -> u16 {
+/// Checks if preferred port is available, otherwise returns a random available port.
+pub fn find_free_port(preferred_port: Option<u16>) -> u16 {
+	// Try to bind to preferred port if provided.
+	if let Some(port) = preferred_port {
+		if TcpListener::bind(format!("127.0.0.1:{}", port)).is_ok() {
+			return port;
+		}
+	}
+
+	// Else, fallback to a random available port
 	TcpListener::bind("127.0.0.1:0")
 		.expect("Failed to bind to an available port")
 		.local_addr()
-		.expect("Failed to retrieve local address")
+		.expect("Failed to retrieve local address. This should never occur.")
 		.port()
 }
 
@@ -105,7 +113,7 @@ mod test {
 
 	#[test]
 	fn find_free_port_works() -> Result<()> {
-		let port = find_free_port();
+		let port = find_free_port(None);
 		let addr = format!("127.0.0.1:{}", port);
 		// Constructs the TcpListener from the above port
 		let listener = TcpListener::bind(&addr);

crates/pop-contracts/src/call.rs

@@ -385,7 +385,7 @@ mod tests {
 
 	#[tokio::test]
 	async fn call_works() -> Result<()> {
-		let random_port = find_free_port();
+		let random_port = find_free_port(None);
 		let localhost_url = format!("ws://127.0.0.1:{}", random_port);
 		let temp_dir = new_environment("testing")?;
 		let current_dir = env::current_dir().expect("Failed to get current directory");

crates/pop-contracts/src/node/mod.rs

@@ -239,7 +239,7 @@ mod tests {
 	#[ignore = "Works fine locally but is causing issues when running tests in parallel in the CI environment."]
 	#[tokio::test]
 	async fn run_contracts_node_works() -> Result<(), Error> {
-		let random_port = find_free_port();
+		let random_port = find_free_port(None);
 		let localhost_url = format!("ws://127.0.0.1:{}", random_port);
 		let local_url = url::Url::parse(&localhost_url)?;
 

crates/pop-contracts/src/up.rs

@@ -596,7 +596,7 @@ mod tests {
 
 	#[tokio::test]
 	async fn instantiate_and_upload() -> Result<()> {
-		let random_port = find_free_port();
+		let random_port = find_free_port(None);
 		let localhost_url = format!("ws://127.0.0.1:{}", random_port);
 		let temp_dir = new_environment("testing")?;
 		let current_dir = env::current_dir().expect("Failed to get current directory");