Add regression test for relay state lock

shared/relay/client/manager_relaystates_test.go

@@ -0,0 +1,62 @@
+package client
+
+import (
+	"testing"
+	"time"
+)
+
+// TestRelayStates_DoesNotBlockWhileForeignRelayConnecting is a regression test for
+// status calls hanging behind an in-progress relay dial.
+//
+// openConnVia establishes a new foreign relay like this:
+//
+//	rt = NewRelayTrack()
+//	rt.Lock()                          // track write-lock
+//	m.relayClients[serverAddress] = rt
+//	m.relayClientsMutex.Unlock()
+//	...
+//	err := relayClient.Connect(m.ctx)  // network dial, held UNDER rt.Lock()
+//	...
+//	rt.Unlock()                        // released only after Connect returns/times out
+//
+// So while a relay is being dialed, its RelayTrack write-lock is held for the whole
+// dial (up to serverResponseTimeout per transport attempt, times the transport
+// fallback chain, times however many relays are being dialed at once).
+//
+// RelayStates() — reached from the daemon status path via
+// peer.Status.GetFullStatus() -> GetRelayStates() -> Manager.RelayStates() — takes
+// rt.RLock() on every tracked relay. A reader lock blocks while a writer holds the
+// lock, so a single foreign relay mid-Connect stalls RelayStates(), and therefore
+// `netbird status -d`, for the full dial timeout. #6547 moved this off the shared
+// map lock but the per-track RLock still blocks the status path.
+//
+// This test recreates the exact in-progress-dial state (track present in the map
+// with its write-lock held) and asserts RelayStates() does not wait on it.
+func TestRelayStates_DoesNotBlockWhileForeignRelayConnecting(t *testing.T) {
+	m := &Manager{
+		relayClients: make(map[string]*RelayTrack),
+	}
+
+	// Mirror openConnVia's state during a live dial: a track in the map whose
+	// write-lock is held for the duration of relayClient.Connect().
+	rt := NewRelayTrack()
+	rt.Lock()
+	m.relayClients["relay.example.com:443"] = rt
+	// Release at the end so a (buggy) blocked RelayStates goroutine can unwind
+	// instead of leaking past the test.
+	t.Cleanup(rt.Unlock)
+
+	done := make(chan []RelayConnState, 1)
+	go func() {
+		done <- m.RelayStates()
+	}()
+
+	select {
+	case <-done:
+		// RelayStates returned without waiting for the in-progress dial. Good.
+	case <-time.After(2 * time.Second):
+		t.Fatal("RelayStates() blocked on a relay track whose Connect() is in progress " +
+			"(rt.Lock held across the dial in openConnVia); `netbird status -d` hangs for " +
+			"the relay dial timeout")
+	}
+}