Unit-testing grpc functions in golang - unit-testing

Question

I have created a function that utilizes the grpc package in golang. I don't know if it is relevant but the purpose is the communication with a GoBGP router over grpc. An example is the following function which prints all the peers (neighbors) of the router:
func (gc *Grpc) Peers(conn *grpc.ClientConn) error {
defer conn.Close()
c := pb.NewGobgpApiClient(conn)
ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
defer cancel()
p := pb.ListPeerRequest{}
peer, err := c.ListPeer(ctx, &p)
if err != nil {
return err
}
for {
res, err := peer.Recv()
if err != nil {
return err
}
fmt.Println(res)
}
return nil
}
Now, I want to create unit tests for the function. To do so, I used google.golang.org/grpc/test/bufconn package, and initialized the following:
type server struct {
pb.UnimplementedGobgpApiServer
}
func (s *server) ListDefinedSet(in *pb.ListDefinedSetRequest, ls pb.GobgpApi_ListDefinedSetServer) error {
return nil
}
var lis *bufconn.Listener
const bufSize = 1024 * 1024
func init() {
lis = bufconn.Listen(bufSize)
s := grpc.NewServer()
pb.RegisterGobgpApiServer(s, &server{})
go func() {
if err := s.Serve(lis); err != nil {
fmt.Println("Server failed!")
}
}()
}
func bufDialer(context.Context, string) (net.Conn, error) {
return lis.Dial()
}
This way, I can run a unit-test creating a connection as follows:
ctx := context.Background()
conn, _ := grpc.DialContext(ctx, "bufnet", grpc.WithContextDialer(bufDialer), grpc.WithInsecure())
Peers(conn)
However, the problem is that the stream seems to be always empty and thus the peer.Recv()
always returns EOF. Is there any way to populate the stream with dummy data? If you have experience, is my methodology correct?