Several months ago, with the release of Android Nougat, Google had showcased the fully revamped notifications system. However, there were many complaints from WhatsApp users stating that the app's notifications feature had not been optimized for the latest version of the Android.
On the other hand, WhatsApp might have been ignoring Google's guidelines for the new redesigned notifications system in Nougat. WhatsApp was in fact not making use of the new system as it should have.
While users were suffering, the messaging app has finally decided to update its app to feature full support for Android Nougat's notifications system. WhatsApp is rolling out a beta version (2.17.13.) of the app.
Apparently with WhatsApp v2.17.13 beta version all the problems within the app have been fixed. And unlike earlier, where the app used to just show the latest messages, the app will now show all unread messages from a single conversation. If you also want to reply from the notifications bar, the messages will not disappear even if a new message is received in the same conversation thread.
And, if you get multiple messages from multiple conversations, these messages will be bundled in one notification. You can unbundle them and reply to each conversation separately, all without ever leaving the notification area and diving into the app. In addition, with the updated WhatsApp complete notifications support is also available from both the lock screen and notification pane. If you try to reply you will be asked to enter your pin, pattern, or fingerprint.
The beta version will be available via the Google Play beta program. So, if you do want to try out the new WhatsApp then you have to become a WhatsApp Android beta tester via Google Play. You just have to go to WhatsApp's listing page on Google Play store and choose the "I'm in" option. Once you have done that you'll become a beta tester and you will be able to update your app to the latest beta build.