Testing

When writing tests for your Connect for Go application, invoke your service through a client and a transport, just like production callers. Calling service methods directly may seem convenient, but it skips the setup performed by connect.Server: the context carries no CallInfo, and interceptors don’t run. For most tests, use an in-process server. For tests that must cover the wire protocol, run a full HTTP server.

Testing with an in-process server

To exercise the full RPC path without binding a port, use the in-process transport from connectrpc.com/connect/v2/connectinprocess. It dispatches RPCs directly to a connect.Server without any networking. It sets up the context and runs the same interceptor and error paths as a network transport:

func TestGreetService(t *testing.T) {
  server := connect.NewServer()
  greetv1connect.RegisterGreetServiceHandler(server, &GreetServer{})

  client := greetv1connect.NewGreetServiceClient(
    connect.NewClient(connectinprocess.New(server)),
  )

  res, err := client.Greet(t.Context(), &greetv1.GreetRequest{Name: "Jane"})
  if err != nil {
    t.Fatalf("Greet: %v", err)
  }
  if got, want := res.GetGreeting(), "Hello, Jane!"; got != want {
    t.Errorf("Greeting = %q, want %q", got, want)
  }
}

Streaming RPCs work the same way, using the generated stream types.

By default, messages are deep-copied between the client and the server with connectinprocess.ProtoCopy, so tests behave like a network transport even when a handler mutates its request. Use connectinprocess.WithCopyFunc to override the copy strategy.

The in-process transport isn’t limited to tests. It’s also useful in production for delegating calls between services running in the same process. Learn more in the in-process transport documentation.

Testing with a running server

Running a full HTTP server gives you behavior that is closest to a real deployment. Use this approach for tests that must cover the wire protocol, such as custom codecs, compression, or h2c configuration. Mount the server on an httptest.Server and point a connecthttp transport at it:

func TestGreetServiceHTTP(t *testing.T) {
  server := connect.NewServer()
  greetv1connect.RegisterGreetServiceHandler(server, &GreetServer{})
  mux := http.NewServeMux()
  connecthttp.Mount(mux, server)
  ts := httptest.NewServer(mux)
  defer ts.Close()

  client := greetv1connect.NewGreetServiceClient(
    connect.NewClient(connecthttp.NewTransport(ts.Client(), ts.URL)),
  )

  res, err := client.Greet(t.Context(), &greetv1.GreetRequest{Name: "Jane"})
  if err != nil {
    t.Fatalf("Greet: %v", err)
  }
  if got, want := res.GetGreeting(), "Hello, Jane!"; got != want {
    t.Errorf("Greeting = %q, want %q", got, want)
  }
}