fix(content): 전체 탭 pagination 스크롤을 안정화한다

app/src/main/java/kr/co/vividnext/sodalive/v2/main/content/ContentMainFragment.kt

@@ -411,11 +411,11 @@ class ContentMainFragment : BaseFragment<FragmentV2MainContentBinding>(
         hideAllTabEmptyError()
         updateAllTabGridItemWidth()
         if (state.selectedType.usesSeriesItems()) {
-            binding.rvContentAllItems.adapter = contentAllSeriesCardAdapter
+            setAllTabAdapterIfNeeded(contentAllSeriesCardAdapter)
             contentAllAudioCardAdapter.submitItems(emptyList())
             contentAllSeriesCardAdapter.submitItems(state.seriesItems)
         } else {
-            binding.rvContentAllItems.adapter = contentAllAudioCardAdapter
+            setAllTabAdapterIfNeeded(contentAllAudioCardAdapter)
             contentAllSeriesCardAdapter.submitItems(emptyList())
             contentAllAudioCardAdapter.submitItems(state.audioItems)
         }
@@ -439,6 +439,11 @@ class ContentMainFragment : BaseFragment<FragmentV2MainContentBinding>(
         contentAllSeriesCardAdapter.setGridItemWidthPx(widthPx)
     }
 
+    private fun setAllTabAdapterIfNeeded(adapter: RecyclerView.Adapter<*>) {
+        if (binding.rvContentAllItems.adapter == adapter) return
+        binding.rvContentAllItems.adapter = adapter
+    }
+
     private fun bindAllTabEmpty(state: MainContentAllTabUiState.Empty) {
         bindAllTabControls(state)
         binding.layoutContentAllSurface.visibility = View.VISIBLE
@@ -485,7 +490,6 @@ class ContentMainFragment : BaseFragment<FragmentV2MainContentBinding>(
     }
 
     private fun clearAllTabItems() {
-        binding.rvContentAllItems.adapter = null
         contentAllAudioCardAdapter.submitItems(emptyList())
         contentAllSeriesCardAdapter.submitItems(emptyList())
     }

app/src/main/java/kr/co/vividnext/sodalive/v2/main/content/ui/ContentAllAudioCardAdapter.kt

@@ -2,6 +2,7 @@ package kr.co.vividnext.sodalive.v2.main.content.ui
 
 import android.view.LayoutInflater
 import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
 import kr.co.vividnext.sodalive.databinding.ItemContentAudioCardBinding
 import kr.co.vividnext.sodalive.extensions.loadUrl
@@ -17,12 +18,13 @@ class ContentAllAudioCardAdapter(
     fun setGridItemWidthPx(widthPx: Int) {
         if (widthPx <= 0 || gridItemWidthPx == widthPx) return
         gridItemWidthPx = widthPx
-        notifyDataSetChanged()
+        if (items.isNotEmpty()) notifyItemRangeChanged(0, items.size)
     }
 
-    fun submitItems(items: List<MainContentAllAudioUiModel>) {
+    fun submitItems(newItems: List<MainContentAllAudioUiModel>) {
-        this.items = items
+        val diffResult = DiffUtil.calculateDiff(ContentAllAudioDiffCallback(items, newItems))
-        notifyDataSetChanged()
+        items = newItems
+        diffResult.dispatchUpdatesTo(this)
     }
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
@@ -41,6 +43,20 @@ class ContentAllAudioCardAdapter(
 
     override fun getItemCount(): Int = items.size
 
+    private class ContentAllAudioDiffCallback(
+        private val oldList: List<MainContentAllAudioUiModel>,
+        private val newList: List<MainContentAllAudioUiModel>
+    ) : DiffUtil.Callback() {
+        override fun getOldListSize(): Int = oldList.size
+        override fun getNewListSize(): Int = newList.size
+
+        override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean =
+            oldList[oldItemPosition].audioContentId == newList[newItemPosition].audioContentId
+
+        override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean =
+            oldList[oldItemPosition] == newList[newItemPosition]
+    }
+
     class ViewHolder(
         private val binding: ItemContentAudioCardBinding,
         private val onAudioClick: (Long) -> Unit

app/src/main/java/kr/co/vividnext/sodalive/v2/main/content/ui/ContentAllSeriesCardAdapter.kt

@@ -2,6 +2,7 @@ package kr.co.vividnext.sodalive.v2.main.content.ui
 
 import android.view.LayoutInflater
 import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
 import kr.co.vividnext.sodalive.databinding.ItemContentAllSeriesCardBinding
 import kr.co.vividnext.sodalive.extensions.loadUrl
@@ -17,12 +18,13 @@ class ContentAllSeriesCardAdapter(
     fun setGridItemWidthPx(widthPx: Int) {
         if (widthPx <= 0 || gridItemWidthPx == widthPx) return
         gridItemWidthPx = widthPx
-        notifyDataSetChanged()
+        if (items.isNotEmpty()) notifyItemRangeChanged(0, items.size)
     }
 
-    fun submitItems(items: List<MainContentAllSeriesUiModel>) {
+    fun submitItems(newItems: List<MainContentAllSeriesUiModel>) {
-        this.items = items
+        val diffResult = DiffUtil.calculateDiff(ContentAllSeriesDiffCallback(items, newItems))
-        notifyDataSetChanged()
+        items = newItems
+        diffResult.dispatchUpdatesTo(this)
     }
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
@@ -41,6 +43,20 @@ class ContentAllSeriesCardAdapter(
 
     override fun getItemCount(): Int = items.size
 
+    private class ContentAllSeriesDiffCallback(
+        private val oldList: List<MainContentAllSeriesUiModel>,
+        private val newList: List<MainContentAllSeriesUiModel>
+    ) : DiffUtil.Callback() {
+        override fun getOldListSize(): Int = oldList.size
+        override fun getNewListSize(): Int = newList.size
+
+        override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean =
+            oldList[oldItemPosition].seriesId == newList[newItemPosition].seriesId
+
+        override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean =
+            oldList[oldItemPosition] == newList[newItemPosition]
+    }
+
     class ViewHolder(
         private val binding: ItemContentAllSeriesCardBinding,
         private val onSeriesClick: (Long) -> Unit

app/src/test/java/kr/co/vividnext/sodalive/v2/main/content/ContentMainFragmentSourceTest.kt

@@ -572,6 +572,59 @@ class ContentMainFragmentSourceTest {
         assertSourceContains(seriesCard, "172f / 122f")
     }
 
+    @Test
+    fun `content 전체 탭 pagination 렌더링은 RecyclerView adapter를 보존한다`() {
+        val source = projectFile(
+            "app/src/main/java/kr/co/vividnext/sodalive/v2/main/content/ContentMainFragment.kt"
+        ).readText()
+        val bindContentSource = source.substringFrom("private fun bindAllTabContent")
+        val clearItemsSource = source.substringFrom("private fun clearAllTabItems")
+        val destroyViewSource = source.substringFrom("override fun onDestroyView")
+
+        assertSourceContains(source, "private fun setAllTabAdapterIfNeeded(adapter: RecyclerView.Adapter<*>)")
+        assertSourceContains(source, "if (binding.rvContentAllItems.adapter == adapter) return")
+        assertSourceContains(bindContentSource, "setAllTabAdapterIfNeeded(contentAllSeriesCardAdapter)")
+        assertSourceContains(bindContentSource, "setAllTabAdapterIfNeeded(contentAllAudioCardAdapter)")
+        assertFalse(
+            "페이지 추가 상태 재렌더링은 같은 adapter를 직접 재대입하면 스크롤 위치가 흔들릴 수 있다.",
+            bindContentSource.contains("binding.rvContentAllItems.adapter = contentAll")
+        )
+        assertFalse(
+            "Loading/Empty/Error 렌더링의 item clear는 adapter를 분리하지 않아야 한다.",
+            clearItemsSource.contains("binding.rvContentAllItems.adapter = null")
+        )
+        assertSourceContains(destroyViewSource, "binding.rvContentAllItems.adapter = null")
+    }
+
+    @Test
+    fun `content 전체 탭 adapter는 DiffUtil로 변경분만 반영한다`() {
+        val audioAdapter = projectFile(
+            "app/src/main/java/kr/co/vividnext/sodalive/v2/main/content/ui/ContentAllAudioCardAdapter.kt"
+        ).readText()
+        val seriesAdapter = projectFile(
+            "app/src/main/java/kr/co/vividnext/sodalive/v2/main/content/ui/ContentAllSeriesCardAdapter.kt"
+        ).readText()
+        val audioSubmitSource = audioAdapter.substringFrom("fun submitItems")
+        val seriesSubmitSource = seriesAdapter.substringFrom("fun submitItems")
+
+        assertSourceContains(audioAdapter, "import androidx.recyclerview.widget.DiffUtil")
+        assertSourceContains(seriesAdapter, "import androidx.recyclerview.widget.DiffUtil")
+        assertSourceContains(audioSubmitSource, "DiffUtil.calculateDiff")
+        assertSourceContains(seriesSubmitSource, "DiffUtil.calculateDiff")
+        assertSourceContains(audioSubmitSource, "diffResult.dispatchUpdatesTo(this)")
+        assertSourceContains(seriesSubmitSource, "diffResult.dispatchUpdatesTo(this)")
+        assertSourceContains(audioAdapter, "oldList[oldItemPosition].audioContentId ==")
+        assertSourceContains(seriesAdapter, "oldList[oldItemPosition].seriesId ==")
+        assertSourceContains(audioAdapter, "oldList[oldItemPosition] == newList[newItemPosition]")
+        assertSourceContains(seriesAdapter, "oldList[oldItemPosition] == newList[newItemPosition]")
+        assertFalse(audioSubmitSource.contains("notifyDataSetChanged()"))
+        assertFalse(seriesSubmitSource.contains("notifyDataSetChanged()"))
+        assertFalse(audioAdapter.contains("notifyDataSetChanged()"))
+        assertFalse(seriesAdapter.contains("notifyDataSetChanged()"))
+        assertSourceContains(audioAdapter, "notifyItemRangeChanged(0, items.size)")
+        assertSourceContains(seriesAdapter, "notifyItemRangeChanged(0, items.size)")
+    }
+
     private fun banner(
         eventItem: EventItem? = null,
         creatorId: Long? = null,