tests: add openmetrics encoding test

Author: Frando

iroh/src/endpoint.rs

@@ -2092,6 +2092,7 @@ mod tests {
 
     use std::time::Instant;
 
+    use iroh_metrics::{service::MetricsSource, MetricsGroupSet};
     use iroh_relay::http::Protocol;
     use n0_future::StreamExt;
     use rand::SeedableRng;
@@ -2849,11 +2850,15 @@ mod tests {
     #[tokio::test]
     #[traced_test]
     async fn metrics_smoke() -> testresult::TestResult {
+        let secret_key = SecretKey::from_bytes(&[0u8; 32]);
         let client = Endpoint::builder()
+            .secret_key(secret_key)
             .relay_mode(RelayMode::Disabled)
             .bind()
             .await?;
+        let secret_key = SecretKey::from_bytes(&[1u8; 32]);
         let server = Endpoint::builder()
+            .secret_key(secret_key)
             .relay_mode(RelayMode::Disabled)
             .alpns(vec![TEST_ALPN.to_vec()])
             .bind()
@@ -2893,6 +2898,18 @@ mod tests {
         assert_eq!(m.magicsock.connection_handshake_success.get(), 1);
         assert!(m.magicsock.recv_datagrams.get() > 0);
 
+        // test openmetrics encoding with labeled subregistries per endpoint
+        let mut registry = iroh_metrics::Registry::default();
+        client.metrics().register(
+            registry.sub_registry_with_label(("id".into(), client.node_id().fmt_short().into())),
+        );
+        server.metrics().register(
+            registry.sub_registry_with_label(("id".into(), server.node_id().fmt_short().into())),
+        );
+        let s = registry.encode_openmetrics()?;
+        assert!(s.contains(r#"magicsock_nodes_contacted_directly_total{id="3b6a27bcce"} 1"#));
+        assert!(s.contains(r#"magicsock_nodes_contacted_directly_total{id="8a88e3dd74"} 1"#));
+
         Ok(())
     }
 }