feat(banner): 배너 preview 회귀 테스트를 추가한다

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/banner/BannerAdapter.kt

@@ -16,6 +16,7 @@ class BannerAdapter(
 
     private val items = mutableListOf<BannerItem>()
     private var itemSizePx: Int = ViewGroup.LayoutParams.MATCH_PARENT
+    private var previewImageResId: Int = 0
 
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BannerViewHolder {
         val view = LayoutInflater.from(parent.context).inflate(R.layout.item_banner, parent, false)
@@ -32,14 +33,24 @@ class BannerAdapter(
     }
 
     fun submitItems(items: List<BannerItem>) {
+        val previousItemCount = itemCount
         this.items.clear()
         this.items.addAll(items)
-        notifyDataSetChanged()
+        val newItemCount = itemCount
+        when {
+            previousItemCount == 0 && newItemCount > 0 -> notifyItemRangeInserted(0, newItemCount)
+            previousItemCount > 0 && newItemCount == 0 -> notifyItemRangeRemoved(0, previousItemCount)
+            previousItemCount == newItemCount -> notifyItemRangeChanged(0, newItemCount)
+            else -> {
+                notifyItemRangeRemoved(0, previousItemCount)
+                notifyItemRangeInserted(0, newItemCount)
+            }
+        }
     }
 
     fun setItemSizePx(itemSizePx: Int) {
         this.itemSizePx = itemSizePx
-        notifyDataSetChanged()
+        notifyItemsChanged()
     }
 
     fun setOnClickItem(listener: ((BannerItem) -> Unit)?) {
@@ -50,6 +61,11 @@ class BannerAdapter(
         onBindImage = listener
     }
 
+    fun setPreviewImageResource(resId: Int) {
+        previewImageResId = resId
+        notifyItemsChanged()
+    }
+
     fun toRealIndex(position: Int): Int = if (items.isEmpty()) 0 else position % items.size
 
     fun startPosition(realIndex: Int): Int {
@@ -74,6 +90,7 @@ class BannerAdapter(
                 height = ViewGroup.LayoutParams.MATCH_PARENT
             }
             setRadiusClipping(imageView)
+            if (previewImageResId != 0) imageView.setImageResource(previewImageResId)
             onBindImage?.invoke(imageView, item)
             itemView.setOnClickListener { onClickItem?.invoke(item) }
         }
@@ -88,6 +105,11 @@ class BannerAdapter(
         }
     }
 
+    private fun notifyItemsChanged() {
+        val count = itemCount
+        if (count > 0) notifyItemRangeChanged(0, count)
+    }
+
     private companion object {
         const val VIRTUAL_ITEM_COUNT = Int.MAX_VALUE
     }

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/banner/BannerView.kt

@@ -59,6 +59,7 @@ class BannerView @JvmOverloads constructor(
         separatorText = findViewById(R.id.tv_banner_counter_separator)
         totalCountText = findViewById(R.id.tv_banner_total_count)
         setUpRecyclerView()
+        applyPreviewAttributes(attrs)
         updateCounter()
     }
 
@@ -114,6 +115,29 @@ class BannerView @JvmOverloads constructor(
         adapter.setOnBindImage(listener)
     }
 
+    private fun applyPreviewAttributes(attrs: AttributeSet?) {
+        if (attrs == null) return
+
+        val typedArray = context.obtainStyledAttributes(attrs, R.styleable.BannerView)
+        try {
+            val previewItemCount = typedArray.getInt(R.styleable.BannerView_bannerPreviewItemCount, 0)
+            val previewCurrentIndex = typedArray.getInt(R.styleable.BannerView_bannerPreviewCurrentIndex, 0)
+            val previewImageResId = typedArray.getResourceId(R.styleable.BannerView_bannerPreviewImage, 0)
+            if (previewImageResId != 0) adapter.setPreviewImageResource(previewImageResId)
+            if (previewItemCount > 0) {
+                items = List(previewItemCount) { index ->
+                    BannerItem(bannerId = "preview-$index", imageUrl = "")
+                }
+                currentIndex = BannerState.from(previewItemCount, previewCurrentIndex).currentIndex
+                visibility = VISIBLE
+                adapter.submitItems(items)
+                scrollToCurrentBanner()
+            }
+        } finally {
+            typedArray.recycle()
+        }
+    }
+
     private fun setUpRecyclerView() {
         requireNotNull(recyclerView).apply {
             layoutManager = LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false)

app/src/test/java/kr/co/vividnext/sodalive/v2/widget/banner/BannerViewTest.kt

@@ -17,6 +17,7 @@ import org.junit.Assert.assertSame
 import org.junit.Assert.assertTrue
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.robolectric.Robolectric
 import org.robolectric.RobolectricTestRunner
 import org.robolectric.Shadows.shadowOf
 import org.robolectric.annotation.Config
@@ -100,6 +101,41 @@ class BannerViewTest {
         assertEquals("02", view.findViewById<TextView>(R.id.tv_banner_total_count).text.toString())
     }
 
+    @Test
+    fun `배너 view는 preview 속성의 count와 current index를 counter에 반영한다`() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        val attrs = Robolectric.buildAttributeSet()
+            .addAttribute(R.attr.bannerPreviewItemCount, "5")
+            .addAttribute(R.attr.bannerPreviewCurrentIndex, "2")
+            .build()
+
+        val view = BannerView(context, attrs)
+
+        assertEquals(View.VISIBLE, view.visibility)
+        assertEquals(View.VISIBLE, view.findViewById<View>(R.id.layout_banner_counter).visibility)
+        assertEquals("03", view.findViewById<TextView>(R.id.tv_banner_current_index).text.toString())
+        assertEquals("05", view.findViewById<TextView>(R.id.tv_banner_total_count).text.toString())
+    }
+
+    @Test
+    fun `배너 view는 preview image 속성을 image view에 적용한다`() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        val attrs = Robolectric.buildAttributeSet()
+            .addAttribute(R.attr.bannerPreviewItemCount, "1")
+            .addAttribute(R.attr.bannerPreviewImage, "@drawable/bg_banner_preview_placeholder")
+            .build()
+
+        val view = BannerView(context, attrs)
+        view.measure(exactly(402.dpToPx()), exactly(402.dpToPx()))
+        view.layout(0, 0, 402.dpToPx(), 402.dpToPx())
+        val recyclerView = view.findViewById<RecyclerView>(R.id.rv_banner)
+        val holder = recyclerView.findViewHolderForAdapterPosition(0)
+            ?: recyclerView.adapter!!.onCreateViewHolder(recyclerView, 0).also { recyclerView.adapter!!.onBindViewHolder(it, 0) }
+        val imageView = holder.itemView.findViewById<ImageView>(R.id.iv_banner)
+
+        assertNotNull(imageView.drawable)
+    }
+
     @Test
     fun `배너 view는 정사각형 item 크기와 좌우 padding 및 간격을 적용한다`() {
         val view = inflateBannerView()
@@ -166,6 +202,34 @@ class BannerViewTest {
         assertEquals(0, itemOffset.right)
     }
 
+    @Test
+    fun `배너 item은 click listener가 null이어도 클릭으로 crash가 발생하지 않는다`() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        val adapter = BannerAdapter()
+        adapter.submitItems(listOf(sampleItem("1")))
+        adapter.setOnClickItem(null)
+        val holder = adapter.onCreateViewHolder(FrameLayout(context), 0)
+        adapter.onBindViewHolder(holder, 0)
+
+        assertTrue(holder.itemView.performClick())
+    }
+
+    @Test
+    fun `배너 view는 첫 번째 배너 클릭 시 첫 번째 item을 callback으로 전달한다`() {
+        val view = inflateBannerView()
+        val firstItem = sampleItem("1")
+        var clickedItem: BannerItem? = null
+
+        view.setOnBannerClickListener { clickedItem = it }
+        view.setItems(listOf(firstItem))
+        val recyclerView = view.findViewById<RecyclerView>(R.id.rv_banner)
+        val holder = recyclerView.adapter!!.onCreateViewHolder(recyclerView, 0)
+        recyclerView.adapter!!.onBindViewHolder(holder, 0)
+        holder.itemView.performClick()
+
+        assertEquals(firstItem, clickedItem)
+    }
+
     @Test
     fun `배너 item image는 radius clipping 대상으로 설정된다`() {
         val context = ApplicationProvider.getApplicationContext<Context>()