The document discusses the speaker's experience transitioning from Ruby to Go by creating a microservice with over 5,000 commits. It covers comparisons between the languages, difficulties encountered, testing strategies using mocks, dependency management, and design patterns in Go. The speaker emphasizes starting simply, testing rigorously, establishing clear contracts, and sharing experiences.

1. package main
func main() {
ola()
defer obrigado()
start()
}

2. André Leoni
golang & ruby
enjoei.com.br

3. do ruby ao golang
o que aprendi criando um microserviço depois de 5000 commits

6. comparativo

7. propósito

8. agile
previsibilidade
testes automatizados

9. dificuldades

10. “não é possível visualizar o suficiente
do design de um grande software para
entender todas as suas implicações
antes de construir qualquer coisa"
A Philosophy of Software Design, 2nd Edition - John K. Ousterhout

11. comece simples

12. dúvidas

13. suporte ao aws
lambda

14. compartilhamento
de codebase

15. testes unitários

16. bibliotecas

18. import (
"github.com/DATA-DOG/go-sqlmock"
"github.com/jinzhu/gorm"
…
func TestCreateMyTable
() {
// Inicializa repo com a biblioteca sqlMock
mytable = mytable{ID: 1}
sqlmock.ExpectBegin()
sqlmock.ExpectExec(
regexp.QuoteMeta(`INSERT INTO "mytable" ("id") VALUES ($1)`)).
WithArgs(mytable.ID).
WillReturnResult
(sqlmock.NewResult(1))
sqlmock.ExpectCommit()
result, err := repo.Create(result)
assert.NoError(rs.T(), err)
assert.Equal(rs.T(), mytable, result)

20. // myFunc uses an SDK service client to make a
request to Amazon DynamoDB.
func getFromDB(svc dynamodbiface.DynamoDBAPI) bool {
// Make svc.BatchExecuteStatement request
}
func main() {
sess := session.New()
svc := dynamodb.New(sess)
getFromDB(svc)
}

21. type mockDynamoDBClient struct {
dynamodbiface.DynamoDBAPI
}
func (m *mockDynamoDBClient) BatchExecuteStatement (
input *dynamodb.BatchExecuteStatementInput)
(*dynamodb.BatchExecuteStatementOutput, error) {
// mock response/functionality
}
func TestgetFromDB(t *testing.T) {
mockSvc := &mockDynamoDBClient{}
getFromDB(mockSvc)
// Verify myFunc's functionality
}

22. mockery

23. link para github
https://github.com/vektra/mockery
comando para gerar os mocks
docker run -v "$PWD":/src -w /src vektra/mockery --all

24. package geometry
// Geometry is the geometry interface
for the geometrical forms
type Geometry interface {
Area() float64
Perim() float64
}

25. package geometry
// Measure receives a Geometry format and
returns the area and perim of them
func Measure(g Geometry) (float64, float64) {
return g.Area(), g.Perim()
}

26. // Code generated by mockery v2.13.1. DO NOT EDIT.
package mocks
import mock "github.com/stretchr/testify/mock"
// Geometry is an autogenerated mock type for the Geometry type
type Geometry struct {
mock.Mock
}
…
…
// Area provides a mock function with given fields:
func (_m *Geometry) Area() float64 {
ret := _m.Called()
var r0 float64
if rf, ok := ret.Get(0).(func() float64); ok {
r0 = rf()
} else {

27. package geometry
…
func TestMeasure(t *testing.T) {
geometryMock := mocks.Geometry{}
geometryMock.On("Area").Return(2.5)
geometryMock.On("Perim").Return(4.8)
givenArea, givenPerim := Measure(&geometryMock)
assert.Equal(t, givenArea, 2.5)
assert.Equal(t, givenPerim, 4.8)
}

28. é muito importante que os
modulos tenham contratos
bem estabelecidos

29. staging

30. time

31. package apptime
import "time"
// Now() returns a mocked value of time
var Now = func() time.Time {
return time.Now()
}

32. package apptime
import "time"
func MockTestsTime(customtime time.Time) {
Now = func() time.Time { return customtime }
}

33. padrão de
projeto

34. dependência cíclica

35. problema soluções

36. DDD

38. context

39. controle de paralelismo

40. monitoramento

42. func apiAction(ctx context.Context, ...) {
...
span, ctx := opentracing.StartSpanFromContext(ctx, "/api/action")
defer span.Finish()
getFromDatabase(ctx)
...
func getFromDatabase(ctx context.Context, ...) {
...
span, ctx := opentracing.StartSpanFromContext(ctx,
"getFromDatabase")
defer span.Finish()
...

43. func My(ctx context.Context)

44. comentários

45. godoc -http=:6060

51. convenções

52. package persistence
...
type productPersistence struct {
db *pg.DB
}
func NewProductPersistence (db *pg.DB) productPersistence {
return productPersistence{db: db}
}
func (pp productPersistence) Get(ctx context.Context) []entity.Product
{
// pp.doSomething
}

53. package persistence
...
type UpdateInput {
Query string
}
type UpdateOutput {
Products []entity.Product
}
...
func (pp productPersistence) Update(ctx context.Context, ui UpdateInput)
(UpdateOutput, error) {
// pp.doSomething
}

54. https://go.dev/doc/effective_go

55. crie suas próprias
experiências…
e para finalizar….

56. …e compartilhe!

57. alguns links
● https://ri.enjoei.com/pt-br/informacoes-aos-investidores/central-de-resu
ltados/
http://dddsample.sourceforge.net/architecture.html
● https://docs.aws.amazon.com/sdk-for-go/api/service/dynamodb/dynam
odbiface/
● https://pg.uptrace.dev/faq/#how-to-test-mock-database
● https://github.com/go-pg/pg