Maintain Running Tasks order in Desktop mode

Fixes: 345034545
Test: TaskbarRecentAppsControllerTest
Flag: com.android.launcher3.enable_recents_in_taskbar
Change-Id: I4ab856c5293625c5279d4713450e5ea2d3b0ed85

quickstep/src/com/android/launcher3/taskbar/TaskbarRecentAppsController.kt

@@ -156,9 +156,16 @@ class TaskbarRecentAppsController(
         }
         val tasks = desktopTask?.tasks ?: emptyList()
         // Kind of hacky, we wrap each single task in the Desktop as a GroupTask.
-        val desktopTaskAsList = tasks.map { GroupTask(it) }
+        var desktopTaskAsList = tasks.map { GroupTask(it) }
         // TODO(b/315344726 Multi-instance support): dedupe Tasks of the same package too.
-        return dedupeHotseatTasks(desktopTaskAsList, shownHotseatItems)
+        desktopTaskAsList = dedupeHotseatTasks(desktopTaskAsList, shownHotseatItems)
+        val desktopPackages = desktopTaskAsList.map { it.packageNames }
+        // Remove any missing Tasks.
+        val newShownTasks = shownTasks.filter { it.packageNames in desktopPackages }.toMutableList()
+        val newShownPackages = newShownTasks.map { it.packageNames }
+        // Add any new Tasks, maintaining the order from previous shownTasks.
+        newShownTasks.addAll(desktopTaskAsList.filter { it.packageNames !in newShownPackages })
+        return newShownTasks.toList()
     }
 
     private fun computeShownRecentTasks(): List<GroupTask> {

quickstep/tests/src/com/android/launcher3/taskbar/TaskbarRecentAppsControllerTest.kt

@@ -230,6 +230,78 @@ class TaskbarRecentAppsControllerTest : TaskbarBaseTestCase() {
         assertThat(recentAppsController.minimizedAppPackages).isEmpty()
     }
 
+    @Test
+    fun onRecentTasksChanged_inDesktopMode_shownTasks_maintainsOrder() {
+        setInDesktopMode(true)
+        val originalOrder = listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2)
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages = originalOrder,
+            recentTaskPackages = emptyList()
+        )
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages = listOf(RUNNING_APP_PACKAGE_2, RUNNING_APP_PACKAGE_1),
+            recentTaskPackages = emptyList()
+        )
+        val shownPackages = recentAppsController.shownTasks.flatMap { it.packageNames }
+        assertThat(shownPackages).isEqualTo(originalOrder)
+    }
+
+    @Test
+    fun onRecentTasksChanged_inDesktopMode_addTask_shownTasks_maintainsOrder() {
+        setInDesktopMode(true)
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages = listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2),
+            recentTaskPackages = emptyList()
+        )
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages =
+                listOf(RUNNING_APP_PACKAGE_2, RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_3),
+            recentTaskPackages = emptyList()
+        )
+        val shownPackages = recentAppsController.shownTasks.flatMap { it.packageNames }
+        val expectedOrder =
+            listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2, RUNNING_APP_PACKAGE_3)
+        assertThat(shownPackages).isEqualTo(expectedOrder)
+    }
+
+    @Test
+    fun onRecentTasksChanged_inDesktopMode_removeTask_shownTasks_maintainsOrder() {
+        setInDesktopMode(true)
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages =
+                listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2, RUNNING_APP_PACKAGE_3),
+            recentTaskPackages = emptyList()
+        )
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages = listOf(RUNNING_APP_PACKAGE_2, RUNNING_APP_PACKAGE_1),
+            recentTaskPackages = emptyList()
+        )
+        val shownPackages = recentAppsController.shownTasks.flatMap { it.packageNames }
+        assertThat(shownPackages).isEqualTo(listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2))
+    }
+
+    @Test
+    fun onRecentTasksChanged_enterDesktopMode_shownTasks_onlyIncludesRunningTasks() {
+        setInDesktopMode(false)
+        val runningTaskPackages = listOf(RUNNING_APP_PACKAGE_1, RUNNING_APP_PACKAGE_2)
+        val recentTaskPackages = listOf(RECENT_PACKAGE_1, RECENT_PACKAGE_2)
+        prepareHotseatAndRunningAndRecentApps(
+            hotseatPackages = emptyList(),
+            runningTaskPackages = runningTaskPackages,
+            recentTaskPackages = recentTaskPackages
+        )
+        setInDesktopMode(true)
+        recentTasksChangedListener.onRecentTasksChanged()
+        val shownPackages = recentAppsController.shownTasks.flatMap { it.packageNames }
+        assertThat(shownPackages).containsExactlyElementsIn(runningTaskPackages)
+    }
+
     private fun prepareHotseatAndRunningAndRecentApps(
         hotseatPackages: List<String>,
         runningTaskPackages: List<String>,