Test RPC service developed in using TWIRP

Question

I'd like to test a sample Twirp RPC service. The sample service is from Twirp official website.

Protobuf definition is as follows:

syntax = "proto3";

package helloservice;
option go_package = "helloservice";

service HelloWorld {
  rpc Hello(HelloReq) returns (HelloResp);
}

message HelloReq {
  string subject = 1;
}

message HelloResp {
  string text = 1;
}

Server implementation:

type HelloWorldServer struct{}

func (s *HelloWorldServer) Hello(ctx context.Context, req *pb.HelloReq) (*pb.HelloResp, error) {
    return &pb.HelloResp{Text: "Hello " + req.Subject}, nil
}

I tried the solution suggested here, but there's some confusion in ClientConn vs HTTPClient. So far, I have this

var Once sync.Once
const bufSize = 1024 * 1024
var listener *bufconn.Listener

func InitTestServer(t *testing.T) *gomock.Controller {
    Once.Do(func(){
        listener = bufconn.Listen(bufSize)
        server := &server.HelloWorldServer{}
        twirpHandler := pb.NewHelloWorldServer(server, nil)
        mux := http.NewServeMux()
        mux.Handle(twirpHandler.PathPrefix(), twirpHandler)
        httpServer := http.Server{
            Handler: mux,
        }
        go func() {
            if err := httpServer.Serve(listener); err != nil {
                if err != http.ErrServerClosed {
                    log.Fatalln("Failed to start http listener", "error", err)
                }
            }
        }()
    })
    ctrl := gomock.NewController(t)
    return ctrl
}

func bufDialer(context.Context, string) (net.Conn, error) {
    return listener.Dial()
}

func TestCreate(t *testing.T) {
    //ctrl := InitTestServer(t)
    InitTestServer(t)
    ctx := context.Background()
    conn, err := grpc.DialContext(ctx, "", grpc.WithInsecure(), grpc.WithContextDialer(bufDialer))
    // conn is of type *ClientConn
    if err != nil {
        t.Fatalf("Failed to dial bufnet: %v", err)
    }
    defer conn.Close()
    //NewHelloWorldJSONClient accepts only HTTPClient
    client := pb.NewHelloWorldJSONClient(conn)
    response, err := client.Hello(ctx, &pb.HelloReq{
        Subject: "sample",
    })
    t.Log(response, err)
}

Any way to convert one into the other, or any other way to test out a Twirp RPC?

Answer 1

You can use net/http/httptest to accomplish a test of this kind.

1. Create the handler using pb.NewHelloWorldServer and giving it the server implementation struct.
2. Create httptest.NewServer using the handler.
3. Use the httptest server's .URL in pb.NewHelloWorldJSONClient (or protobuf, or both).

As a quick example:

package main

import (
    "context"
    "net/http"
    "net/http/httptest"
    "testing"

    pb "github.com/3ventic/twirphelloworld/rpc"
)

// InitTestServer initializes a test server for HelloWorld and returns its address
func InitTestServer() string {
    handler := pb.NewHelloWorldServer(&HelloWorldServer{})
    server := httptest.NewServer(handler)
    return server.URL
}

func TestHello(t *testing.T) {
    url := InitTestServer()
    clients := map[string]pb.HelloWorld{
        "json": pb.NewHelloWorldJSONClient(url, http.DefaultClient),
        "pb":   pb.NewHelloWorldProtobufClient(url, http.DefaultClient),
    }

    for typ, client := range clients {
        t.Run(typ, func(t *testing.T) {
            ctx := context.Background()
            result, err := client.Hello(ctx, &pb.HelloReq{
                Subject: "test",
            })
            if err != nil {
                t.Error(err)
                t.FailNow()
            }
            if result.Text != "Hello test" {
                t.Errorf("result didn't match 'Hello test', was '%s'", result.Text)
            }
        })
    }
}

Full example available here