SDL does not send SubscribeButton request if HMI responds to UnsubscribeButton request once default timeout expires

[VjKlepikov]

Bug Report

SDL does not send SubscribeButton request if HMI responds to UnsubscribeButton request once default timeout expires

Occurrences:

Rare ~1%

Reproduction Steps

1. Mobile app is subscribed for "button"
2. Mobile app requests UnsubscribeButton("button")
3. SDL sends Buttons.UnsubscribeButton("button", appId) to HMI
4. HMI does not respond during default timeout
5. SDL responds UnsubscribeButton(GENERIC_ERROR) to mobile app
6. HMI sends Buttons.UnsubscribeButton(SUCCESS) to SDL

Expected Behavior

SDL sends Buttons.SubscribeButton("button", appId) to HMI receive response Buttons.SubscribeButton(SUCCESS) and keep actual subscribed state for SDL does not send SubscribeButton response to mobile app

Observed Behavior

SDL does not send Buttons.SubscribeButton ("button", appId) to HMI

OS & Version Information

• OS/Version: Ubuntu 18.04
• SDL Core Version: https://github.com/smartdevicelink/sdl_core/tree/develop (b74c738)

Test Case, Sample Code, and / or Example App

Test scripts: ./test_scripts/API/ButtonSubscription/SubscribeButton_UnsubscribeButton/004_UnsubscribeButton_SDL_send_SubscribeButton_after_Unsubscribe_SUCCESS_timeout.lua

Logs: Logs.tar.gz

[VjKlepikov]

Please notice this is a non-regression issue. It's also reproduced on 8.0