chore(net): improve network service launch error diagnostic (#2068)

crates/net/network/tests/it/main.rs

@@ -1,5 +1,6 @@
 mod connect;
 mod requests;
 mod session;
+mod startup;
 
 fn main() {}

crates/net/network/tests/it/startup.rs

@@ -0,0 +1,42 @@
+use reth_discv4::{Discv4Config, DEFAULT_DISCOVERY_PORT};
+use reth_network::{
+    error::{NetworkError, ServiceKind},
+    Discovery, NetworkConfigBuilder, NetworkManager,
+};
+use reth_provider::test_utils::NoopProvider;
+use secp256k1::SecretKey;
+use std::{
+    io,
+    net::{Ipv4Addr, SocketAddr, SocketAddrV4},
+};
+
+fn is_addr_in_use_kind(err: NetworkError, kind: ServiceKind) -> bool {
+    match err {
+        NetworkError::AddressAlreadyInUse { kind: k, error } => {
+            k == kind && error.kind() == io::ErrorKind::AddrInUse
+        }
+        _ => false,
+    }
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn test_listener_addr_in_use() {
+    let secret_key = SecretKey::new(&mut rand::thread_rng());
+    let config = NetworkConfigBuilder::new(secret_key).build(NoopProvider::default());
+    let _network = NetworkManager::new(config).await.unwrap();
+    let config = NetworkConfigBuilder::new(secret_key).build(NoopProvider::default());
+    let addr = config.discovery_addr;
+    let result = NetworkManager::new(config).await;
+    assert!(is_addr_in_use_kind(result.err().unwrap(), ServiceKind::Listener(addr)));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn test_discovery_addr_in_use() {
+    let secret_key = SecretKey::new(&mut rand::thread_rng());
+    let disc_config = Discv4Config::default();
+    let addr = SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, DEFAULT_DISCOVERY_PORT));
+    let _discovery = Discovery::new(addr, secret_key, Some(disc_config), None).await.unwrap();
+    let disc_config = Discv4Config::default();
+    let result = Discovery::new(addr, secret_key, Some(disc_config), None).await;
+    assert!(is_addr_in_use_kind(result.err().unwrap(), ServiceKind::Discovery(addr)));
+}