Fix #1873: Fix OnboardingFragmentTest test cases on Robolectric (#2482)

* fixed one test

* fix 4 remaining tests

* try fixing tests bu introducing scrollview

* tried adding scrollview

* fix AndroidManifest.xml

* fix nit

* fix basic set of tests

* fixed 3 failing tests

* removed extra changes

* removed extra changes

* try fixing tests with testCoroutineDispatchers

* try advancedUntilIdle()

* tried migrating to viewpager2

* tried implementing new methods

* Replace ViewPager with ViewPager2

* Add ignore annotations

* fix lint

* add dependencies to BUILD.bazel

* remove unnecessary ignore annotations

* fix lint

* fix lint

* fix lint

* fix lint error

* remove redundant lines

* Fix Viewpager2 regressions

* Fix lint errors.

* Remove comments

* Fix all test cases on Robolectric

* Try fixing flakiness in espresso

* Revert "Try fixing flakiness in espresso"

This reverts commit 2151c45

* Replace isDisplayed() with isCompletelyDisplayed()

* Fix suggested changes

* Try fixing test cases by using isADescendantOf()

* Revert changes

* Try stabilizing ttion est cases by changing configuration

* Revert last commit to remove unwanted configuration changes

* Fix ktlint error

* Try adding custom ViewMatcher

* Add custom ViewMatcher

* Add custom ViewAction for scrolling ViewPager pages

* Disable smooth scrolling to fix test cases

* Remove holder.setIsRecycleable(false) and optimise perform()

* Remove unnecessary id of constraintLayout in onboarding_slide.xml

* Replace advancedUntilIdle bu runCurrent wherever applicable

* Remove unnecessary delay

* Add argument comment for smoothScroll

* Add a space after argument comment

* Fix suggested changes.

app/src/main/java/org/oppia/android/app/onboarding/OnboardingFragmentPresenter.kt

@@ -6,18 +6,14 @@ import android.view.ViewGroup
 import android.widget.ImageView
 import android.widget.LinearLayout
 import androidx.appcompat.app.AppCompatActivity
-import androidx.core.text.TextUtilsCompat
-import androidx.core.view.ViewCompat
 import androidx.fragment.app.Fragment
-import androidx.viewpager.widget.ViewPager
+import androidx.viewpager2.widget.ViewPager2
 import org.oppia.android.R
 import org.oppia.android.app.fragment.FragmentScope
 import org.oppia.android.app.viewmodel.ViewModelProvider
 import org.oppia.android.databinding.OnboardingFragmentBinding
 import org.oppia.android.util.statusbar.StatusBarColor
-import java.util.Locale
 import javax.inject.Inject
-import kotlin.collections.ArrayList
 
 /** The presenter for [OnboardingFragment]. */
 @FragmentScope
@@ -28,7 +24,6 @@ class OnboardingFragmentPresenter @Inject constructor(
   private val viewModelProviderFinalSlide: ViewModelProvider<OnboardingSlideFinalViewModel>
 ) : OnboardingNavigationListener {
   private val dotsList = ArrayList<ImageView>()
-  private lateinit var onboardingPagerAdapter: OnboardingPagerAdapter
   private lateinit var binding: OnboardingFragmentBinding
 
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
@@ -50,18 +45,11 @@ class OnboardingFragmentPresenter @Inject constructor(
   }
 
   private fun setUpViewPager() {
-    onboardingPagerAdapter =
+    val adapter =
       OnboardingPagerAdapter(fragment.requireContext(), getOnboardingSlideFinalViewModel())
-    binding.onboardingSlideViewPager.adapter = onboardingPagerAdapter
-    // TODO (#2194 ): Remove this once the implementation is updated to ViewPager2
-    val isRTL = TextUtilsCompat
-      .getLayoutDirectionFromLocale(Locale.getDefault()) == ViewCompat.LAYOUT_DIRECTION_RTL
-    if (isRTL) {
-      binding.onboardingSlideViewPager.rotationY = 180f
-    }
-    binding.onboardingSlideViewPager.addOnPageChangeListener(
-      object :
-        ViewPager.OnPageChangeListener {
+    binding.onboardingSlideViewPager.adapter = adapter
+    binding.onboardingSlideViewPager.registerOnPageChangeCallback(
+      object : ViewPager2.OnPageChangeCallback() {
         override fun onPageScrollStateChanged(state: Int) {
         }
 

app/src/main/java/org/oppia/android/app/onboarding/OnboardingPagerAdapter.kt

@@ -2,65 +2,81 @@ package org.oppia.android.app.onboarding
 
 import android.content.Context
 import android.view.LayoutInflater
-import android.view.View
 import android.view.ViewGroup
-import android.widget.ScrollView
-import androidx.core.text.TextUtilsCompat
-import androidx.core.view.ViewCompat
-import androidx.viewpager.widget.PagerAdapter
+import androidx.recyclerview.widget.RecyclerView
 import org.oppia.android.databinding.OnboardingSlideBinding
 import org.oppia.android.databinding.OnboardingSlideFinalBinding
-import java.util.Locale
 
-/** Adapter to control the slide details in onboarding flow. */
+private const val VIEW_TYPE_TITLE_TEXT = 1
+private const val VIEW_TYPE_STORY_ITEM = 2
+
 class OnboardingPagerAdapter(
   val context: Context,
   val onboardingSlideFinalViewModel: OnboardingSlideFinalViewModel
-) : PagerAdapter() {
-  // TODO (#2194 ): Remove this once the implementation is updated to ViewPager2
-  val isRTL = TextUtilsCompat
-    .getLayoutDirectionFromLocale(Locale.getDefault()) == ViewCompat.LAYOUT_DIRECTION_RTL
-  override fun instantiateItem(container: ViewGroup, position: Int): Any {
-    if (position == TOTAL_NUMBER_OF_SLIDES - 1) {
-      val binding =
-        OnboardingSlideFinalBinding.inflate(
+) :
+  RecyclerView.Adapter<RecyclerView.ViewHolder>() {
+
+  override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
+    return when (viewType) {
+      VIEW_TYPE_TITLE_TEXT -> {
+        val binding = OnboardingSlideBinding.inflate(
           LayoutInflater.from(context),
-          container,
+          parent,
           false
         )
-      binding.viewModel = onboardingSlideFinalViewModel
-      if (isRTL) {
-        binding.finalLayout!!.rotationY = 180f
+        OnboardingSlideViewHolder(binding)
       }
-
-      container.addView(binding.root)
-      return binding.root
+      VIEW_TYPE_STORY_ITEM -> {
+        val binding =
+          OnboardingSlideFinalBinding.inflate(
+            LayoutInflater.from(context),
+            parent,
+            false
+          )
+        OnboardingSlideFinalViewHolder(binding)
+      }
+      else -> throw IllegalArgumentException("Invalid view type: $viewType")
     }
+  }
 
-    val binding = OnboardingSlideBinding.inflate(
-      LayoutInflater.from(context),
-      container,
-      false
-    )
-    if (isRTL) {
-      binding.root.rotationY = 180f
+  override fun getItemViewType(position: Int): Int {
+    return if (position == TOTAL_NUMBER_OF_SLIDES - 1) {
+      VIEW_TYPE_STORY_ITEM
+    } else {
+      VIEW_TYPE_TITLE_TEXT
     }
-    val onboardingSlideViewModel =
-      OnboardingSlideViewModel(context, ViewPagerSlide.getSlideForPosition(position))
-    binding.viewModel = onboardingSlideViewModel
-    container.addView(binding.root)
-    return binding.root
   }
 
-  override fun getCount(): Int {
+  override fun getItemCount(): Int {
     return TOTAL_NUMBER_OF_SLIDES
   }
 
-  override fun isViewFromObject(view: View, `object`: Any): Boolean {
-    return view == `object`
+  override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
+    when (holder.itemViewType) {
+      VIEW_TYPE_TITLE_TEXT -> {
+        val onboardingSlideViewModel =
+          OnboardingSlideViewModel(context, ViewPagerSlide.getSlideForPosition(position))
+        (holder as OnboardingSlideViewHolder).bind(onboardingSlideViewModel)
+      }
+      VIEW_TYPE_STORY_ITEM -> {
+        (holder as OnboardingSlideFinalViewHolder).bind(onboardingSlideFinalViewModel)
+      }
+    }
+  }
+
+  inner class OnboardingSlideViewHolder(
+    private val binding: OnboardingSlideBinding
+  ) : RecyclerView.ViewHolder(binding.root) {
+    fun bind(onboardingSlideViewModel: OnboardingSlideViewModel) {
+      binding.viewModel = onboardingSlideViewModel
+    }
   }
 
-  override fun destroyItem(container: ViewGroup, position: Int, `object`: Any) {
-    container.removeView(`object` as ScrollView)
+  inner class OnboardingSlideFinalViewHolder(
+    private val binding: OnboardingSlideFinalBinding
+  ) : RecyclerView.ViewHolder(binding.root) {
+    fun bind(onboardingSlideFinalViewModel: OnboardingSlideFinalViewModel) {
+      binding.viewModel = onboardingSlideFinalViewModel
+    }
   }
 }

app/src/main/res/layout-land/onboarding_fragment.xml

@@ -20,10 +20,10 @@
     android:layout_height="match_parent"
     android:background="@color/oppiaBackgroundYellowIvory">
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
       android:id="@+id/onboarding_slide_view_pager"
       android:layout_width="match_parent"
-      android:layout_height="0dp"
+      android:layout_height="match_parent"
       android:layout_marginBottom="0dp"
       android:overScrollMode="never"
       android:scrollbars="none"

app/src/main/res/layout-sw600dp-land/onboarding_fragment.xml

@@ -20,10 +20,10 @@
     android:layout_height="match_parent"
     android:background="@color/oppiaBackgroundYellowIvory">
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
       android:id="@+id/onboarding_slide_view_pager"
       android:layout_width="match_parent"
-      android:layout_height="0dp"
+      android:layout_height="match_parent"
       android:overScrollMode="never"
       android:scrollbars="none"
       app:layout_constraintBottom_toTopOf="@id/get_started_container"

app/src/main/res/layout-sw600dp-land/onboarding_slide.xml

@@ -26,8 +26,8 @@
         android:layout_width="0dp"
         android:layout_height="0dp"
         android:adjustViewBounds="true"
-        android:src="@{viewModel.slideImage}"
         android:importantForAccessibility="no"
+        android:src="@{viewModel.slideImage}"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintDimensionRatio="40:39"
         app:layout_constraintStart_toStartOf="parent"

app/src/main/res/layout-sw600dp-port/onboarding_fragment.xml

@@ -20,7 +20,7 @@
     android:layout_height="match_parent"
     android:background="@color/oppiaBackgroundYellowIvory">
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
       android:id="@+id/onboarding_slide_view_pager"
       android:layout_width="match_parent"
       android:layout_height="0dp"

app/src/main/res/layout/onboarding_fragment.xml

@@ -20,7 +20,7 @@
     android:layout_height="match_parent"
     android:background="@color/oppiaBackgroundYellowIvory">
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
       android:id="@+id/onboarding_slide_view_pager"
       android:layout_width="match_parent"
       android:layout_height="0dp"