Exit from processConnResults after all tries (#2621)

* Exit from processConnResults after all tries

If all server is unavailable then the server picker never return
because we never close the result channel.
Count the number of the results and exit when we reached the
expected size

relay/client/picker_test.go

@@ -0,0 +1,31 @@
+package client
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+)
+
+func TestServerPicker_UnavailableServers(t *testing.T) {
+	sp := ServerPicker{
+		TokenStore: nil,
+		PeerID:     "test",
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	go func() {
+		_, err := sp.PickServer(ctx, []string{"rel://dummy1", "rel://dummy2"})
+		if err == nil {
+			t.Error(err)
+		}
+		cancel()
+	}()
+
+	<-ctx.Done()
+	if errors.Is(ctx.Err(), context.DeadlineExceeded) {
+		t.Errorf("PickServer() took too long to complete")
+	}
+}