[Fixes Bug]: After moving between tabs on Bookmark fragment, Bookmarks never loads (#4951)

* Fixed the issue added tests

* Added requested changes

app/src/main/java/fr/free/nrw/commons/bookmarks/pictures/BookmarkPicturesFragment.java

@@ -188,6 +188,10 @@ public class BookmarkPicturesFragment extends DaggerFragment {
             setAdapter(collection);
         } else {
             if (gridAdapter.containsAll(collection)) {
+                progressBar.setVisibility(GONE);
+                statusTextView.setVisibility(GONE);
+                gridView.setVisibility(VISIBLE);
+                gridView.setAdapter(gridAdapter);
                 return;
             }
             gridAdapter.addItems(collection);

app/src/test/kotlin/fr/free/nrw/commons/bookmarks/pictures/BookmarkPicturesFragmentUnitTests.kt

@@ -6,12 +6,17 @@ import android.os.Bundle
 import android.os.Looper.getMainLooper
 import android.view.LayoutInflater
 import android.view.View
+import android.view.View.GONE
+import android.view.View.VISIBLE
 import android.widget.GridView
 import android.widget.ProgressBar
 import android.widget.RelativeLayout
 import android.widget.TextView
 import androidx.fragment.app.FragmentManager
 import androidx.fragment.app.FragmentTransaction
+import com.nhaarman.mockitokotlin2.any
+import com.nhaarman.mockitokotlin2.times
+import com.nhaarman.mockitokotlin2.verify
 import fr.free.nrw.commons.Media
 import fr.free.nrw.commons.R
 import fr.free.nrw.commons.TestAppAdapter
@@ -19,6 +24,7 @@ import fr.free.nrw.commons.TestCommonsApplication
 import fr.free.nrw.commons.category.GridViewAdapter
 import fr.free.nrw.commons.media.MediaClient
 import fr.free.nrw.commons.profile.ProfileActivity
+import media
 import org.junit.Assert
 import org.junit.Before
 import org.junit.Test
@@ -46,9 +52,15 @@ class BookmarkPicturesFragmentUnitTests {
     private lateinit var context: Context
 
     private lateinit var view: View
-    private lateinit var statusTextView: TextView
+
-    private lateinit var progressBar: ProgressBar
+    @Mock
-    private lateinit var gridView: GridView
+    lateinit var statusTextView: TextView
+
+    @Mock
+    lateinit var progressBar: ProgressBar
+
+    @Mock
+    lateinit var gridView: GridView
 
     @Mock
     private lateinit var parentLayout: RelativeLayout
@@ -87,9 +99,6 @@ class BookmarkPicturesFragmentUnitTests {
 
         view = LayoutInflater.from(activity)
             .inflate(R.layout.fragment_bookmarks_pictures, null) as View
-        statusTextView = view.findViewById(R.id.statusMessage)
-        progressBar = view.findViewById(R.id.loadingImagesProgressBar)
-        gridView = view.findViewById(R.id.bookmarkedPicturesList)
 
         fragment.statusTextView = statusTextView
         fragment.progressBar = progressBar
@@ -102,7 +111,11 @@ class BookmarkPicturesFragmentUnitTests {
 
         fragment.controller = controller
 
-        Whitebox.setInternalState(fragment, "gridAdapter", gridAdapter)
+        Whitebox.setInternalState(fragment, "gridAdapter", GridViewAdapter(
+            context,
+            0,
+            listOf(media())
+        ))
     }
 
     @Test
@@ -171,6 +184,22 @@ class BookmarkPicturesFragmentUnitTests {
         method.invoke(fragment, throwable)
     }
 
+    @Test
+    @Throws(Exception::class)
+    fun testHandleSuccess() {
+        gridAdapter.addItems(listOf(media()))
+        val method: Method = BookmarkPicturesFragment::class.java.getDeclaredMethod(
+            "handleSuccess",
+            List::class.java
+        )
+        method.isAccessible = true
+        method.invoke(fragment, listOf(media()))
+        verify(progressBar, times(1)).setVisibility(GONE)
+        verify(statusTextView, times(1)).setVisibility(GONE)
+        verify(gridView, times(1)).setVisibility(VISIBLE)
+        verify(gridView, times(1)).setAdapter(any())
+    }
+
     @Test
     @Throws(Exception::class)
     fun testInitErrorView() {