Test: cover scroll-to-first-unread VM action and wired pill snapshot

Two coverage additions for the new unread-pill surface:

- MessageListViewModelTest gains a case for disableUnreadLabelButton on a
  fixture with no active unread label, asserting state stays untouched. This
  exercises the VM's delegating method and the controller's early-return
  guard end-to-end.

- MessageListTest gains a snapshot variant rendering MessageList with an
  active UnreadLabel and an inline UnreadSeparatorItemState. The snapshot
  exercises the wired pill through the public state-only MessageList,
  Messages.DefaultMessagesHelperContent, and the
  ChatComponentFactory.ScrollToFirstUnreadButton slot in inspection mode.

Author: andremion

stream-chat-android-compose/src/test/kotlin/io/getstream/chat/android/compose/ui/messages/MessageListTest.kt

@@ -32,11 +32,13 @@ import io.getstream.chat.android.models.ChannelCapabilities
 import io.getstream.chat.android.previewdata.PreviewChannelUserRead
 import io.getstream.chat.android.previewdata.PreviewMessageData
 import io.getstream.chat.android.previewdata.PreviewUserData
+import io.getstream.chat.android.ui.common.feature.messages.list.MessageListController
 import io.getstream.chat.android.ui.common.state.messages.list.DateSeparatorItemState
 import io.getstream.chat.android.ui.common.state.messages.list.MessageItemState
 import io.getstream.chat.android.ui.common.state.messages.list.MessageListState
 import io.getstream.chat.android.ui.common.state.messages.list.MessagePosition
 import io.getstream.chat.android.ui.common.state.messages.list.SystemMessageItemState
+import io.getstream.chat.android.ui.common.state.messages.list.UnreadSeparatorItemState
 import org.junit.Rule
 import org.junit.Test
 import java.util.Calendar
@@ -150,6 +152,13 @@ internal class MessageListTest : PaparazziComposeTest {
             )
         }
     }
+
+    @Test
+    fun `scroll to first unread pill`() {
+        snapshotWithDarkMode {
+            MessageList(messageListState = UnreadLabelMessageListState)
+        }
+    }
 }
 
 private val Date1 = Calendar.getInstance().apply { set(2022, 1, 1, 1, 1) }.time
@@ -250,6 +259,15 @@ private val TwoMessagesListState = MessageListState(
     ),
 )
 
+private val UnreadLabelMessageListState = LoadedMessageListState.copy(
+    messageItems = listOf(UnreadSeparatorItemState(unreadCount = 9)) + LoadedMessageListState.messageItems,
+    unreadLabel = MessageListController.UnreadLabel(
+        unreadCount = 9,
+        lastReadMessageId = PreviewMessageData.message1.id,
+        buttonVisibility = true,
+    ),
+)
+
 @Composable
 private fun MessageList(
     messagesLazyListState: MessagesLazyListState = rememberMessagesLazyListState(),

stream-chat-android-compose/src/test/kotlin/io/getstream/chat/android/compose/viewmodel/messages/MessageListViewModelTest.kt

@@ -147,6 +147,22 @@ internal class MessageListViewModelTest {
         verify(audioPlayer).pause()
     }
 
+    @Test
+    fun `When disableUnreadLabelButton is called without active unread label, state stays empty`() = runTest {
+        val viewModel = Fixture()
+            .givenCurrentUser()
+            .givenChannelQuery()
+            .givenChannelState()
+            .get()
+
+        // No lastReadMessageId is configured by the fixture, so the calculator never produces an
+        // unread label. Calling disableUnreadLabelButton must early-return on the controller side
+        // and leave the unread state untouched.
+        viewModel.disableUnreadLabelButton()
+
+        viewModel.currentMessagesState.value.unreadLabel `should be equal to` null
+    }
+
     private class Fixture(
         private val chatClient: ChatClient = mock(),
         private val channelId: String = CID,