测试Go中的Nats订阅

huangapple
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英文:

Testing Nats subscription in Go

问题

我有一个函数设计用来监听 Nats 主题并在接收到消息时路由它们：

  1. func (conn *JetStreamConnection) SubscribeMultiple(ctx context.Context, subject string,
  2. 	subscribers ...*SubscriptionCallback) error {
  4. 	callbacks := make(map[string]func(*pnats.NatsMessage) (func(context.Context), error))
  5. 	for _, subscriber := range subscribers {
  6. 		callbacks[subscriber.Category] = subscriber.Callback
  7. 	}
  9. 	fullSubject := fmt.Sprintf("%s.*", subject)
  10. 	sub, err := conn.context.SubscribeSync(fullSubject, nats.Context(ctx))
  11. 	if err != nil {
  12.         return err
  13. 	}
  15. loop:
  16. 	for {
  18. 		select {
  19. 		case <-ctx.Done():
  20. 			break loop
  21. 		default:
  22. 		}
  24. 		msg, err := sub.NextMsgWithContext(ctx)
  25. 		if err != nil {
  26. 			return err
  27. 		}
  29. 		msg.InProgress()
  31. 		var message pnats.NatsMessage
  32. 		if err := conn.unmarshaller(msg.Data, &message); err != nil {
  33. 			msg.Term()
  34. 			return err
  35. 		}
  37. 		actualSubject := fmt.Sprintf("%s.%s", subject, message.Context.Category)
  38. 		subscriber, ok := callbacks[message.Context.Category]
  39. 		if !ok {
  40. 			msg.Nak()
  41. 			continue
  42. 		}
  44. 		callback, err := subscriber(&message)
  45. 		if err == nil {
  46. 			msg.Ack()
  47. 		} else {
  48. 			msg.Nak()
  49. 			return err
  50. 		}
  52. 		callback(ctx)
  53. 	}
  55. 	if err := sub.Unsubscribe(); err != nil {
  56. 		return err
  57. 	}
  59. 	return nil
  60. }

我的问题是，由于 SubscribeSync 函数生成了一个 *nats.Subscription 对象，我无法对测试进行模拟。我该如何在这个对象周围进行测试？

英文:

I have a function designed to listen to a Nats subject and route the messages as it receives them:

  1. func (conn *JetStreamConnection) SubscribeMultiple(ctx context.Context, subject string,
  2. subscribers ...*SubscriptionCallback) error {
  3. callbacks := make(map[string]func(*pnats.NatsMessage) (func(context.Context), error))
  4. for _, subscriber := range subscribers {
  5. callbacks[subscriber.Category] = subscriber.Callback
  6. }
  7. fullSubject := fmt.Sprintf(&quot;%s.*&quot;, subject)
  8. sub, err := conn.context.SubscribeSync(fullSubject, nats.Context(ctx))
  9. if err != nil {
  10. return err
  11. }
  12. loop:
  13. for {
  14. select {
  15. case &lt;-ctx.Done():
  16. break loop
  17. default:
  18. }
  19. msg, err := sub.NextMsgWithContext(ctx)
  20. if err != nil {
  21. return err
  22. }
  23. msg.InProgress()
  24. var message pnats.NatsMessage
  25. if err := conn.unmarshaller(msg.Data, &amp;message); err != nil {
  26. msg.Term()
  27. return err
  28. }
  29. actualSubject := fmt.Sprintf(&quot;%s.%s&quot;, subject, message.Context.Category)
  30. subscriber, ok := callbacks[message.Context.Category]
  31. if !ok {
  32. msg.Nak()
  33. continue
  34. }
  35. callback, err := subscriber(&amp;message)
  36. if err == nil {
  37. msg.Ack()
  38. } else {
  39. msg.Nak()
  40. return err
  41. }
  42. callback(ctx)
  43. }
  44. if err := sub.Unsubscribe(); err != nil {
  45. return err
  46. }
  47. return nil
  48. }

My problem is that, since the SubscribeSync function produces a *nats.Subscription object, I have no way to mock out the test. How can I test around this object?

答案1

得分: 2

你可以将循环放在一个单独的函数中。这个函数可以接受一个描述nats Subscription的接口，而不是*nats.Subscription。这样你就可以使用gomock或其他工具创建Subscription的模拟对象。然后你可以单独测试内部函数。

类似这样的代码：

  1. func (conn *JetStreamConnection) SubscribeMultiple(ctx context.Context, subject string,
  2.     subscribers ...*SubscriptionCallback) error {
  4.     callbacks := make(map[string]func(*pnats.NatsMessage) (func(context.Context), error))
  5.     for _, subscriber := range subscribers {
  6.         callbacks[subscriber.Category] = subscriber.Callback
  7.     }
  9.     fullSubject := fmt.Sprintf("%s.*", subject)
  10.     sub, err := conn.context.SubscribeSync(fullSubject, nats.Context(ctx))
  11.     if err != nil {
  12.         return err
  13.     }
  15.     return run(ctx, sub)
  16. }
  18. //go:generate mockgen -source conn.go -destination ../mocks/conn.go -package mocks
  19. type ISubscription interface{
  20.     NextMsgWithContext(ctx context.Context) (*nats.Msg, error)
  21.     Unsubscribe() error
  22. }
  24. func (conn *JetStreamConnection) run(ctx context.Context, sub ISubscription) error {
  25. loop:
  26.     for {
  28.         select {
  29.         case <-ctx.Done():
  30.             break loop
  31.         default:
  32.         }
  34.         msg, err := sub.NextMsgWithContext(ctx)
  35.         if err != nil {
  36.             return err
  37.         }
  39.         msg.InProgress()
  41.         var message pnats.NatsMessage
  42.         if err := conn.unmarshaller(msg.Data, &message); err != nil {
  43.             msg.Term()
  44.             return err
  45.         }
  47.         actualSubject := fmt.Sprintf("%s.%s", subject, message.Context.Category)
  48.         subscriber, ok := callbacks[message.Context.Category]
  49.         if !ok {
  50.             msg.Nak()
  51.             continue
  52.         }
  54.         callback, err := subscriber(&message)
  55.         if err == nil {
  56.             msg.Ack()
  57.         } else {
  58.             msg.Nak()
  59.             return err
  60.         }
  62.         callback(ctx)
  63.     }
  65.     if err := sub.Unsubscribe(); err != nil {
  66.         return err
  67.     }
  68. }

更新：如果你仍然想测试SubscribeMultiple函数，你可以创建一个只有一个Run函数的Runner结构体，并将其作为JetStreamConnection的依赖项。同样，你可以为Runner创建一个模拟对象，并使用它进行测试。

英文:

You can put your loop in a separate function. This func can accept an interface that describes nats Subscription instead of *nats.Subscription. This way you will be able to create Subscription mocks with gomock or other tools. After that you can test the inside func separately

Something like this:

  1. func (conn *JetStreamConnection) SubscribeMultiple(ctx context.Context, subject string,
  2.     subscribers ...*SubscriptionCallback) error {
  4.     callbacks := make(map[string]func(*pnats.NatsMessage) (func(context.Context), error))
  5.     for _, subscriber := range subscribers {
  6.         callbacks[subscriber.Category] = subscriber.Callback
  7.     }
  9.     fullSubject := fmt.Sprintf(&quot;%s.*&quot;, subject)
  10.     sub, err := conn.context.SubscribeSync(fullSubject, nats.Context(ctx))
  11.     if err != nil {
  12.         return err
  13.     }
  15.     return run(ctx, sub)
  16. }
  18. //go:generate mockgen -source conn.go -destination ../mocks/conn.go -package mocks
  19. type ISubscription interface{
  20.     NextMsgWithContext(ctx context.Context) (*nats.Msg, error)
  21.     Unsubscribe() error
  22. }
  24. func (conn *JetStreamConnection) run(ctx context.Context, sub ISubscription) error {
  25. loop:
  26.     for {
  28.         select {
  29.         case &lt;-ctx.Done():
  30.             break loop
  31.         default:
  32.         }
  34.         msg, err := sub.NextMsgWithContext(ctx)
  35.         if err != nil {
  36.             return err
  37.         }
  39.         msg.InProgress()
  41.         var message pnats.NatsMessage
  42.         if err := conn.unmarshaller(msg.Data, &amp;message); err != nil {
  43.             msg.Term()
  44.             return err
  45.         }
  47.         actualSubject := fmt.Sprintf(&quot;%s.%s&quot;, subject, message.Context.Category)
  48.         subscriber, ok := callbacks[message.Context.Category]
  49.         if !ok {
  50.             msg.Nak()
  51.             continue
  52.         }
  54.         callback, err := subscriber(&amp;message)
  55.         if err == nil {
  56.             msg.Ack()
  57.         } else {
  58.             msg.Nak()
  59.             return err
  60.         }
  62.         callback(ctx)
  63.     }
  65.     if err := sub.Unsubscribe(); err != nil {
  66.         return err
  67.     }
  68. }

upd: if you still want to test SubscribeMultiple, you can create a Runner that will have only one func Run and take it as dependency for JetStreamConnection. Again, you can create a mock for Runner and test with it

huangapple
  • 本文由 发表于 2022年8月4日 15:06:07
  • 转载请务必保留本文链接：https://go.coder-hub.com/73231636.html
  • go
  • nats.io
  • testing
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