mock grpc client request and response using testify - unit-testing

Question

I have been trying to mock my grpc client/server to control the response.
what I'm trying to achieve is the flex testify give us with mocks, and using the once(),times() idea.
so I will explain further lets say I have a go program that run the following:
I want to control each response of the iteration of client.getUser()
type DB struct {
api serviceAPI
}
type service struct {
}
type serviceAPI interface {
getClient() (pb.UserServiceClient, *grpc.ClientConn, error)
}
func (db *DB) getNextUser()(*UserAcc,error){
client := db.api.getClient()
var index uint64 = 0
for {
user = client.getUser(context.Background(), &pb.GetUserRequest{Index: index})
if(user == nil){
return nil,nil
}
if user(!=nil){
fmt.Printl(user)
}
}
}
func (s service) getClient() (pb.UserServiceClient, *grpc.ClientConn, error) {
addr := GetAgentAddress()
conn, _ := grpc.Dial(addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
client := pb.NewUserServiceClient(conn)
return client, conn, nil
}
proto.go
message GetUserRequest{
uint64 index = 1;
}
message GetUserResponse{
bytes user = 1;
}
service userService {
rpc GetUser (GetUserRequest) returns (GetUserResponse);
}
user_grpc.pb.go
type UserServiceClient interface {
GetUser(ctx context.Context, in *GetUserRequest, opts ...grpc.CallOption) (*GetUserResponse, error)
UpdateUser(ctx context.Context, in *UpdateUserRequest, opts ...grpc.CallOption) (*UpdateUserResponse, error)
main_test.go
type MainTestSuite struct {
suite.Suite
}
type serviceMock struct {
mock.Mock
}
type clientMock struct {
mock.Mock
}
func (c *clientMock) UpdateUser(ctx context.Context, in *pb.UpdateUserRequest, opts ...grpc.CallOption) (*pb.UpdateUserResponse, error) {
//TODO implement me
panic("implement me")
}
func (c *clientMock) GetUser(ctx context.Context, in *pb.GetUserRequest, opts ...grpc.CallOption) (*pb.GetUserResponse, error) {
args := c.Called(ctx, in, opts)
return args.Get(0).(*pb.GetUserResponse), args.Error(1)
}
func (service *serviceMock) getClient() (pb.UserServiceClient, *grpc.ClientConn, error) {
args := service.Called()
return args.Get(0).(clientMock), args.Get(1).(*grpc.ClientConn), args.Error(2)
}
func (suite *MainTestSuite) TestGetNextUser() {
t := suite.T()
t.Run("Should successfully get the next User", func(t *testing.T) {
mServiceApi := serviceMock{}
ClientMock := clientMock{}
mServiceApi.On("getClient").Return(ClientMock, nil, nil)
ClientMock.On("GetUser", mock.Anything, mock.Anything, mock.Anything).Return(&pb.GetUserResponse{
User: []bytes("something"),
}, nil).once()
ClientMock.On("GetUser", mock.Anything, mock.Anything, mock.Anything).Return(&pb.GetUserResponse{
User: []bytes("some other user"),
}, nil).once()
ClientMock.On("GetUser", mock.Anything, mock.Anything, mock.Anything).Return(&pb.GetUserResponse{
User: []bytes("something"),
}, nil).once()
db := DB{
api: &mServiceApi,
}
nextUser ,_ := db.getNextUser(true)
assert.Nil(t, nextUser)
})
}
I would like for each iteration of the GetUser command of the client grpc to get different answers using the once() or times() of testify
am I'm mocking the grpc client the right way?
right now i get the following issues:
Cannot use 'args.Get(0).(clientMock)' (type clientMock) as the type pb.UserServiceClient Type does not implement 'pb.UserServiceClient' as the 'UpdateUser' method has a pointer receiver.
any idea why?

Answer 1

I managed to do it with the mockery package and install it by brew
mockery --name=UserServiceClient --unroll-variadic=False