IssueTracker

Component used: navigation
Version used: 1.0.0-alpha1, using SDK 27/28
Devices/Android versions reproduced on: Emulators from API 21 to 26

When a Fragment is set as a "pop" destination for a action, it is "resumed" even though it is not shown on the screen.

I attached a sample projet to show the problem.

Here is the setup:

Very simple MainActivity, with one NavHostFragment and 3 Fragments: FragmentOne, FragmentTwo, FragmentThree.
The nav graph is simple:
* FragmentOne can go to FragmentTwo
* FragmentTwo can go to FragmentThree
  * The "pop" destination of the action is FragmentOne
FragmentOne contains a Log.v() in its onResume() method.

How to reproduce:

* Start the app
  * In Logcat, see "onResume", as the FragmentOne is shown
* Navigate to FragmentTwo
* Navigate to FragmentThree
  * In Logcat, see "onResume", as the FragmentOne is resumed for some reason => BUG ?
* Press back
  * In Logcat, see "onResume", as the FragmentOne is shown

As you see, the FragmentOne is shown only twice on screen, but Logcat shows "onResume" three times.

Now as a counter example:

* Open the Nav Graph and remove the "pop" destination (line 24, app:popUpTo="@+id/fragmentOne")
* Start the app
  * In Logcat, see "onResume", as the FragmentOne is shown
* Navigate to FragmentTwo
* Navigate to FragmentThree
  * In Logcat, you don't see anything
* Press back
  * FragmentTwo is shown, nothing in Logcat
* Press back
  * In Logcat, see "onResume", as the FragmentOne is shown

=> FragmentOne is shown twice, Logcat shows "onResume" twice.

To me it's clearly a bug as the whole lifecycle of FragmentOne is triggered even though the Fragment is never shown on screen.
It cause me a problem: I wanted to refresh my view (doing an HTTP fetch) when the Fragment is resumed. Because of this bug, the fragment fetches from the network even though it is never shown.
I tried to play with isVisible()
(https://developer.android.com/reference/android/support/v4/app/Fragment.html#isVisible() ) but the method returns true even tough the Fragment is not shown.

Any thoughts about this? Thanks!