Add a flag to control re-subscribe functionality.

[redboltz]

This pull request implements a option resubscribe for controlling re-subscribe.
The default value of resubscribe is true. It doesn't break current behavior.
It will fix #664 partially. Partially means, if suback has error payload, then re-subscribe topics should be removed. It is a different issue.

[codecov]

Codecov Report

Merging #665 into master will increase coverage by <.01%.
The diff coverage is 95%.

@@            Coverage Diff             @@
##           master     #665      +/-   ##
==========================================
+ Coverage   92.66%   92.66%   +<.01%     
==========================================
  Files           8        8              
  Lines         668      682      +14     
  Branches      161      167       +6     
==========================================
+ Hits          619      632      +13     
- Misses         49       50       +1

Impacted Files	Coverage Δ
lib/client.js	96.17% <95%> (-0.11%)	⬇️

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[mcollina]

Can you also add a fix for the other issue? There seem to be some new lines that are not covered by unit tests, would you mind adding those too?

Thanks!

[redboltz]

Can you also add a fix for the other issue? There seem to be some new lines that are not covered by unit tests, would you mind adding those too?

Does the other issue mean treat well with suback error? It's OK. I'm not sure the coverage will be satisfied if I add the fix. Anyway I will do.

In order to add the fix, I need to know how do I know suback error code.
http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718068
suback's payload has two information. One is QoS, the other is success/fail bit.

And I found packet.granted[0] is the raw payload. Can I use this?
(packet.payload is null)

[mcollina]

Yes it's the information you are looking for is in the granted property.

[redboltz]

@mcollina , thanks. I implemented the library code. Now I start writing tests. I think that the test server needs to return suback with failure bit 1. How can I do this? I'm studying other tests implementation. But if you give me some advice, it is very helpful.

[mcollina]

You should instantiate a new server and replace the 'subscribe' event. See https://github.com/mqttjs/MQTT.js/blob/master/test/client.js#L128-L149 as an example.

[redboltz]

@mcollina , thank you! I will write tests.

[redboltz]

I implemented the fix for suback error case. I also implemented the test.
It seems that codecov is satisfied.

I implemented the test in abstract_client.js. I'm not sure either abstract_client.js or client.js is an appropriate location to implement the test.
I introduced port variable and I set server2 listening port to port + 49 just like the test you mentioned.

If there is a room to improve, please let me know.

[mcollina]

Thanks, released as v2.12.0.