Testing

Tests run the application with coretest. The grpcclienttest package serves a *grpc.Server in memory, and points a named connection at it, without listening on a port and whatever the configured target.

Fake server

grpcclienttest.Serve serves a test server on the connection:

type fakeUsers struct {
  pb.UnimplementedUsersServer
}

func (fakeUsers) GetUser(_ context.Context, req *pb.GetUserRequest) (*pb.User, error) {
  return &pb.User{Id: req.GetId(), Name: "test_name"}, nil
}

func TestService(t *testing.T) {
  t.Parallel()

  server := grpc.NewServer()
  pb.RegisterUsersServer(server, fakeUsers{})

  var (
    service *app.Service
    spans   *tracetest.InMemoryExporter
    logs    *logtest.InMemoryExporter
  )

  coretest.Start(t, app.New(), grpcclienttest.Serve("users", server), fx.Populate(&service, &spans, &logs))

  name, err := service.UserName(t.Context(), "42")
  require.NoError(t, err)
  assert.Equal(t, "test_name", name)

  spantest.HasSpan(t, spans,
    spantest.WithName("users.v1.Users/GetUser"),
    spantest.WithKind(trace.SpanKindClient),
  )
  logtest.HasRecord(t, logs, logtest.WithBody("grpc client request"), logtest.WithAttributeValue("method", "GetUser"))
}

The connection is plaintext, its target is passthrough:///users. The server is started with the application, and stopped with it.

Application server

grpcclienttest.ServeApp serves the *grpc.Server of the application, provided by the grpcserver module, on the connection. Use it to test a client against the real services, or the trace propagation:

coretest.Start(t,
  core.New(
    grpcserver.Module,
    grpcserver.AsService(&pb.Users_ServiceDesc, NewUsersService),
    grpcclient.Module,
    grpcclient.AsClient("users", pb.NewUsersClient),
  ),
  grpcclienttest.ServeApp("users"),
  fx.Populate(&client, &spans),
)

_, err := client.GetUser(t.Context(), &pb.GetUserRequest{Id: "42"})
require.NoError(t, err)

clientSpans := spantest.Find(spans, spantest.WithName("users.v1.Users/GetUser"), spantest.WithKind(trace.SpanKindClient))
require.Len(t, clientSpans, 1)
spantest.HasSpan(t, spans,
  spantest.WithKind(trace.SpanKindServer),
  spantest.WithParent(clientSpans[0].SpanContext.SpanID()),
)