Allow setting own gRPC server when calling NewService (#400)

* Add `NewServiceWithGrpcServer` to gRPC service

Signed-off-by: pimmerks <[email protected]>

* Apply suggestion of not creating new variable

Signed-off-by: pimmerks <[email protected]>

---------

Signed-off-by: pimmerks <[email protected]>

Author: pimmerks

service/grpc/service.go

@@ -39,16 +39,21 @@ func NewService(address string) (s common.Service, err error) {
 		err = fmt.Errorf("failed to TCP listen on %s: %w", address, err)
 		return
 	}
-	s = newService(lis)
+	s = newService(lis, nil)
 	return
 }
 
 // NewServiceWithListener creates new Service with specific listener.
 func NewServiceWithListener(lis net.Listener, opts ...grpc.ServerOption) common.Service {
-	return newService(lis, opts...)
+	return newService(lis, nil, opts...)
 }
 
-func newService(lis net.Listener, opts ...grpc.ServerOption) *Server {
+// NewServiceWithGrpcServer creates a new Service with specific listener and grpcServer
+func NewServiceWithGrpcServer(lis net.Listener, server *grpc.Server) common.Service {
+	return newService(lis, server)
+}
+
+func newService(lis net.Listener, grpcServer *grpc.Server, opts ...grpc.ServerOption) *Server {
 	s := &Server{
 		listener:        lis,
 		invokeHandlers:  make(map[string]common.ServiceInvocationHandler),
@@ -57,10 +62,13 @@ func newService(lis net.Listener, opts ...grpc.ServerOption) *Server {
 		authToken:       os.Getenv(common.AppAPITokenEnvVar),
 	}
 
-	gs := grpc.NewServer(opts...)
-	pb.RegisterAppCallbackServer(gs, s)
-	pb.RegisterAppCallbackHealthCheckServer(gs, s)
-	s.grpcServer = gs
+	if grpcServer == nil {
+		grpcServer = grpc.NewServer(opts...)
+	}
+
+	pb.RegisterAppCallbackServer(grpcServer, s)
+	pb.RegisterAppCallbackHealthCheckServer(grpcServer, s)
+	s.grpcServer = grpcServer
 
 	return s
 }

service/grpc/service_test.go

@@ -17,6 +17,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc"
 	"google.golang.org/grpc/test/bufconn"
 )
 
@@ -31,13 +32,19 @@ func TestServerWithListener(t *testing.T) {
 	assert.NotNil(t, server)
 }
 
+func TestServerWithGrpcServer(t *testing.T) {
+	grpcServer := grpc.NewServer()
+	server := NewServiceWithGrpcServer(bufconn.Listen(1024*1024), grpcServer)
+	assert.NotNil(t, server)
+}
+
 func TestService(t *testing.T) {
 	_, err := NewService("")
 	assert.Errorf(t, err, "expected error from lack of address")
 }
 
 func getTestServer() *Server {
-	return newService(bufconn.Listen(1024 * 1024))
+	return newService(bufconn.Listen(1024*1024), nil)
 }
 
 func startTestServer(server *Server) {