pubsub: docs example for Subscription.Receive is incorect

[dtam-cybozu]

Client

PubSub

Environment

N/A

Go Environment

N/A

Code

According to this example https://github.com/googleapis/google-cloud-go/blob/main/pubsub/example_test.go#L313-L329 we are supposed to assume that something has gone wrong if err != context.Canceled but I had a very quick skim through the Receive source and it seems like it often returns nil (notably, including when ctx is done).

	err = sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) {
		// TODO: Handle message.
		m.Ack()
	})
	if err != context.Canceled {
		// TODO: Handle error.
	}

Expected behavior

I'm not exactly sure if Receive() ever returns context.Canceled so I can't say whether the condition should look like:

if err != nil {
	// TODO: Handle error.
}

but it should at least look like this if I'm not mistaken:

if err != nil && err != context.Canceled {
	// TODO: Handle error.
}

Please let me know if I've made a mistake, thanks :)

[hongalex]

Good catch. You're correct in that a nil error does not need to be handled.