Espresso: Not able to launch inner fragment

Issue

I am using launchFragmentInContainer<FragmentOne>() to launch fragment and able to perform actions using EspressoMatchers, it's all working fine.

But the issue comes when I want to launch another fragment onClick Of button(this code is inside FragmentOne) but while launching getting an error for FragmentTwo

Example:

onClick {
        val fragment = FragmentTwo.newInstance()
        val transaction = requireActivity().supportFragmentManager.beginTransaction()
        transaction.add(fragmentContainerID, fragment)
        transaction.commit()    
       }

Above code giving error java.lang.IllegalArgumentException: No view found for id 0x4d2 (unknown) for fragment FragmentTwo{bc39d06} (6f4636b5-f441-4e38-956a-47ac91d261bc) id=0x4d2}

How to resolve this inside fragment? or I have to do something in espresso test.

Solution

This issue is coming due to fragmentContainerID which should be unique and used under the hood of launchFragmentInContainer().

So, inside the espresso framework android.R.id.content is used as a fragment Id. This same id should be used while the fragment transaction.

Code Snippet:

var fragmentContainerID = android.R.id.content // It will do the trick and fragment will be added on top of stack

Answered By - Jitesh Mohite