UI test for multi selection in media gallery

This was originally meant to find the cause of crashes caused by
non-unique IDs in the ViewHolder (#15918 and #16194). But the UI test
still succeeded because it didn't carefully craft the fileIds to cause
the issue. Once the actual reason, a collision of an improper hash
function, was found, a unit test for that scenario was added
instead - see prior commit.

Committing this UI test anyways, as it might be able to catch other,
future regressions.

Signed-off-by: Philipp Hasper <vcs@hasper.info>

Author: PhilLab

app/src/androidTest/java/com/owncloud/android/ui/fragment/GalleryFragmentIT.kt

@@ -1,6 +1,7 @@
 /*
  * Nextcloud - Android Client
  *
+ * SPDX-FileCopyrightText: 2026 Philipp Hasper <vcs@hasper.info>
  * SPDX-FileCopyrightText: 2025 Alper Ozturk <alper.ozturk@nextcloud.com>
  * SPDX-FileCopyrightText: 2022 Tobias Kaminsky <tobias@kaminsky.me>
  * SPDX-FileCopyrightText: 2022 Nextcloud GmbH
@@ -12,20 +13,34 @@ import android.graphics.Bitmap
 import android.graphics.Canvas
 import android.graphics.Color
 import android.graphics.Paint
+import android.view.View
+import android.view.ViewGroup
+import android.widget.FrameLayout
+import androidx.recyclerview.widget.RecyclerView
 import androidx.test.core.app.launchActivity
 import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.UiController
+import androidx.test.espresso.ViewAction
 import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.contrib.RecyclerViewActions
+import androidx.test.espresso.contrib.RecyclerViewActions.actionOnItemAtPosition
+import androidx.test.espresso.matcher.ViewMatchers.isAssignableFrom
 import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
 import androidx.test.espresso.matcher.ViewMatchers.isRoot
+import androidx.test.espresso.matcher.ViewMatchers.withId
 import com.nextcloud.test.TestActivity
 import com.owncloud.android.AbstractIT
+import com.owncloud.android.R
 import com.owncloud.android.datamodel.OCFile
 import com.owncloud.android.datamodel.ThumbnailsCacheManager
 import com.owncloud.android.datamodel.ThumbnailsCacheManager.PREFIX_RESIZED_IMAGE
 import com.owncloud.android.lib.common.utils.Log_OC
 import com.owncloud.android.lib.resources.files.model.ImageDimension
+import com.owncloud.android.ui.adapter.GalleryRowHolder
 import com.owncloud.android.utils.ScreenshotTest
+import org.hamcrest.Matchers.allOf
 import org.junit.After
+import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNotNull
 import org.junit.Before
 import org.junit.Test
@@ -85,14 +100,102 @@ class GalleryFragmentIT : AbstractIT() {
         }
     }
 
-    private fun createImage(id: Int, width: Int? = null, height: Int? = null) {
+    @Test
+    fun multiSelect() {
+        val imageCount = 100
+        for (num in 1..imageCount) {
+            // Spread the files over multiple days to also get multiple sections
+            val secondsPerDay = 1L * 24 * 60 * 60
+            createImage(10000000 + num * 7 * secondsPerDay, 700, 300)
+        }
+
+        // Test that scrolling through the whole list is possible without a crash
+        launchActivity<TestActivity>().use { scenario ->
+            lateinit var galleryFragment: GalleryFragment
+            scenario.onActivity { testActivity ->
+                galleryFragment = GalleryFragment()
+                testActivity.addFragment(galleryFragment)
+            }
+            onView(isRoot()).check(matches(isDisplayed()))
+
+            onView(withId(R.id.list_root))
+                .perform(RecyclerViewActions.scrollToLastPosition<GalleryRowHolder>())
+                .perform(RecyclerViewActions.scrollToPosition<GalleryRowHolder>(0))
+        }
+
+        // Test selection of all entries
+        launchActivity<TestActivity>().use { scenario ->
+            lateinit var galleryFragment: GalleryFragment
+            scenario.onActivity { testActivity ->
+                galleryFragment = GalleryFragment()
+                testActivity.addFragment(galleryFragment)
+            }
+            onView(isRoot()).check(matches(isDisplayed()))
+
+            // get the RecyclerView and itemCount on the UI thread
+            val recyclerView = findRecyclerViewRecursively(galleryFragment.view)
+                ?: throw AssertionError("RecyclerView not found")
+            val adapterCount = recyclerView.adapter?.itemCount ?: 0
+
+            // Perform the view action on each adapter position (row)
+            // Match the visible RecyclerView: if there is only one displayed RecyclerView we can match it by class+displayed
+            val recyclerMatcher = allOf(isAssignableFrom(RecyclerView::class.java), isDisplayed())
+
+            for (pos in 0 until adapterCount) {
+                onView(recyclerMatcher)
+                    .perform(actionOnItemAtPosition<RecyclerView.ViewHolder>(pos, longClickAllThumbnailsInRow()))
+            }
+
+            val checked = galleryFragment.commonAdapter.getCheckedItems()
+            assertEquals(imageCount, checked.size)
+        }
+    }
+
+    /** Recursively walk view tree to find the first RecyclerView. Runs on the same thread that calls it. */
+    private fun findRecyclerViewRecursively(root: View?): RecyclerView? {
+        if (root == null) return null
+        if (root is RecyclerView) return root
+        if (root !is ViewGroup) return null
+        for (i in 0 until root.childCount) {
+            val child = root.getChildAt(i)
+            val found = findRecyclerViewRecursively(child)
+            if (found != null) return found
+        }
+        return null
+    }
+
+    /**
+     * For the given row view, long-click each thumbnail inside its FrameLayouts
+     */
+    fun longClickAllThumbnailsInRow(): ViewAction = object : ViewAction {
+        override fun getConstraints() = isDisplayed()
+
+        override fun getDescription() = "Long-click all thumbnail ImageViews inside a GalleryRowHolder"
+
+        override fun perform(uiController: UiController, view: View) {
+            if (view is ViewGroup) {
+                // each child of the row is a FrameLayout representing one gallery cell
+                for (i in 0 until view.childCount) {
+                    val cell = view.getChildAt(i)
+                    if (cell is FrameLayout) {
+                        // GalleryRowHolder builds FrameLayout with children:
+                        // 0 = shimmer, 1 = thumbnail ImageView, 2 = checkbox
+                        val thumbnail = if (cell.childCount > 1) cell.getChildAt(1) else cell
+                        thumbnail.performLongClick()
+                    }
+                }
+            }
+        }
+    }
+
+    private fun createImage(id: Long, width: Int? = null, height: Int? = null) {
         val defaultSize = ThumbnailsCacheManager.getThumbnailDimension().toFloat()
         val file = OCFile("/$id.png").apply {
-            fileId = id.toLong()
+            fileId = id
             remoteId = "$id"
             mimeType = "image/png"
             isPreviewAvailable = true
-            modificationTimestamp = (1658475504 + id.toLong()) * 1000
+            modificationTimestamp = (1658475504 + id) * 1000
             imageDimension = ImageDimension(width?.toFloat() ?: defaultSize, height?.toFloat() ?: defaultSize)
             storageManager.saveFile(this)
         }