Merge changes from topic "taskbar-layout-transition-prepare" into main

* changes:
  Prepare for LayoutTransition with RTL support.
  Split up hotseat and recents into two methods.
  Filter out unsupported items immediately when updating Taskbar.

quickstep/src/com/android/launcher3/taskbar/TaskbarModelCallbacks.java

@@ -208,7 +208,7 @@ public class TaskbarModelCallbacks implements
 
     private void commitHotseatItemUpdates(
             ItemInfo[] hotseatItemInfos, List<GroupTask> recentTasks) {
-        mContainer.updateHotseatItems(hotseatItemInfos, recentTasks);
+        mContainer.updateItems(hotseatItemInfos, recentTasks);
         mControllers.taskbarViewController.updateIconViewsRunningStates();
     }
 

quickstep/src/com/android/launcher3/taskbar/TaskbarView.java

@@ -20,11 +20,14 @@ import static android.view.accessibility.AccessibilityEvent.TYPE_WINDOW_CONTENT_
 import static com.android.launcher3.BubbleTextView.DISPLAY_TASKBAR;
 import static com.android.launcher3.Flags.enableCursorHoverStates;
 import static com.android.launcher3.Flags.enableRecentsInTaskbar;
+import static com.android.launcher3.Flags.taskbarRecentsLayoutTransition;
 import static com.android.launcher3.LauncherSettings.Favorites.ITEM_TYPE_APP_PAIR;
 import static com.android.launcher3.LauncherSettings.Favorites.ITEM_TYPE_FOLDER;
 import static com.android.launcher3.config.FeatureFlags.enableTaskbarPinning;
 import static com.android.launcher3.icons.IconNormalizer.ICON_VISIBLE_AREA_FACTOR;
 
+import static java.util.function.Predicate.not;
+
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Canvas;
@@ -70,7 +73,9 @@ import com.android.systemui.shared.recents.model.Task;
 import com.android.wm.shell.shared.bubbles.BubbleBarLocation;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.function.Predicate;
 
 /**
@@ -108,6 +113,8 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
     // Only non-null when device supports having a Taskbar Overflow button.
     @Nullable private TaskbarOverflowView mTaskbarOverflowView;
 
+    private int mNextViewIndex;
+
     /**
      * Whether the divider is between Hotseat icons and Recents,
      * instead of between All Apps button and Hotseat.
@@ -125,6 +132,8 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
 
     private final int mAllAppsButtonTranslationOffset;
 
+    private final int mNumStaticViews;
+
     public TaskbarView(@NonNull Context context) {
         this(context, null);
     }
@@ -189,6 +198,8 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
 
         // TODO: Disable touch events on QSB otherwise it can crash.
         mQsb = LayoutInflater.from(context).inflate(R.layout.search_container_hotseat, this, false);
+
+        mNumStaticViews = taskbarRecentsLayoutTransition() ? addStaticViews() : 0;
     }
 
     /**
@@ -249,6 +260,24 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
                 && (mIdealNumIcons > oldMaxNumIcons || mIdealNumIcons > mMaxNumIcons);
     }
 
+    /**
+     * Pre-adds views that are always children of this view for LayoutTransition support.
+     * <p>
+     * Normally these views are removed and re-added when updating hotseat and recents. This
+     * approach does not behave well with LayoutTransition, so we instead need to add them
+     * initially and avoid removing them during updates.
+     */
+    private int addStaticViews() {
+        int numStaticViews = 1;
+        addView(mAllAppsButtonContainer);
+        if (mActivityContext.getDeviceProfile().isQsbInline) {
+            addView(mQsb, mIsRtl ? 1 : 0);
+            mQsb.setVisibility(View.INVISIBLE);
+            numStaticViews++;
+        }
+        return numStaticViews;
+    }
+
     @Override
     public void setVisibility(int visibility) {
         boolean changed = getVisibility() != visibility;
@@ -362,12 +391,26 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
         view.setTag(null);
     }
 
-    /**
-     * Inflates/binds the Hotseat views to show in the Taskbar given their ItemInfos.
-     */
-    protected void updateHotseatItems(ItemInfo[] hotseatItemInfos, List<GroupTask> recentTasks) {
-        int nextViewIndex = 0;
-        int numViewsAnimated = 0;
+    /** Inflates/binds the hotseat items and recent tasks to the view. */
+    protected void updateItems(ItemInfo[] hotseatItemInfos, List<GroupTask> recentTasks) {
+        // Filter out unsupported items.
+        hotseatItemInfos = Arrays.stream(hotseatItemInfos)
+                .filter(Objects::nonNull)
+                .toArray(ItemInfo[]::new);
+        // TODO(b/343289567 and b/316004172): support app pairs and desktop mode.
+        recentTasks = recentTasks.stream().filter(not(GroupTask::supportsMultipleTasks)).toList();
+
+        if (taskbarRecentsLayoutTransition()) {
+            updateItemsWithLayoutTransition(hotseatItemInfos, recentTasks);
+        } else {
+            updateItemsWithoutLayoutTransition(hotseatItemInfos, recentTasks);
+        }
+    }
+
+    private void updateItemsWithoutLayoutTransition(
+            ItemInfo[] hotseatItemInfos, List<GroupTask> recentTasks) {
+
+        mNextViewIndex = 0;
         mAddedDividerForRecents = false;
 
         removeView(mAllAppsButtonContainer);
@@ -380,12 +423,101 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
         }
         removeView(mQsb);
 
-        // Add Hotseat icons.
-        for (ItemInfo hotseatItemInfo : hotseatItemInfos) {
-            if (hotseatItemInfo == null) {
-                continue;
-            }
+        updateHotseatItems(hotseatItemInfos);
 
+        if (mTaskbarDividerContainer != null && !recentTasks.isEmpty()) {
+            addView(mTaskbarDividerContainer, mNextViewIndex++);
+            mAddedDividerForRecents = true;
+        }
+
+        updateRecents(recentTasks);
+
+        addView(mAllAppsButtonContainer, mIsRtl ? hotseatItemInfos.length : 0);
+
+        // If there are no recent tasks, add divider after All Apps (unless it's the only view).
+        if (!mAddedDividerForRecents
+                && mTaskbarDividerContainer != null
+                && getChildCount() > 1) {
+            addView(mTaskbarDividerContainer, mIsRtl ? (getChildCount() - 1) : 1);
+        }
+
+        if (mActivityContext.getDeviceProfile().isQsbInline) {
+            addView(mQsb, mIsRtl ? getChildCount() : 0);
+            // Always set QSB to invisible after re-adding.
+            mQsb.setVisibility(View.INVISIBLE);
+        }
+    }
+
+    private void updateItemsWithLayoutTransition(
+            ItemInfo[] hotseatItemInfos, List<GroupTask> recentTasks) {
+
+        // Skip static views and potential All Apps divider, if they are on the left.
+        mNextViewIndex = mIsRtl ? 0 : mNumStaticViews;
+        if (getChildAt(mNextViewIndex) == mTaskbarDividerContainer) {
+            mNextViewIndex++;
+        }
+
+        // Update left section.
+        if (mIsRtl) {
+            updateRecents(recentTasks.reversed());
+        } else {
+            updateHotseatItems(hotseatItemInfos);
+        }
+
+        // Now at theoretical position for recent apps divider.
+        updateRecentsDivider(!recentTasks.isEmpty());
+        if (getChildAt(mNextViewIndex) == mTaskbarDividerContainer) {
+            mNextViewIndex++;
+        }
+
+        // Update right section.
+        if (mIsRtl) {
+            updateHotseatItems(hotseatItemInfos);
+        } else {
+            updateRecents(recentTasks);
+        }
+
+        // Recents divider takes priority.
+        if (!mAddedDividerForRecents) {
+            updateAllAppsDivider();
+        }
+    }
+
+    private void updateRecentsDivider(boolean hasRecents) {
+        if (hasRecents && !mAddedDividerForRecents) {
+            mAddedDividerForRecents = true;
+
+            // Remove possible All Apps divider.
+            if (getChildAt(mNumStaticViews) == mTaskbarDividerContainer) {
+                mNextViewIndex--; // All Apps divider on the left. Need to account for removing it.
+            }
+            removeView(mTaskbarDividerContainer);
+
+            addView(mTaskbarDividerContainer, mNextViewIndex);
+        } else if (!hasRecents && mAddedDividerForRecents) {
+            mAddedDividerForRecents = false;
+            removeViewAt(mNextViewIndex);
+        }
+    }
+
+    private void updateAllAppsDivider() {
+        final int allAppsDividerIndex =
+                mIsRtl ? getChildCount() - mNumStaticViews : mNumStaticViews;
+        if (getChildAt(allAppsDividerIndex) == mTaskbarDividerContainer
+                && getChildCount() == mNumStaticViews + 1) {
+            // Only static views with divider so remove divider.
+            removeView(mTaskbarDividerContainer);
+        } else if (getChildAt(allAppsDividerIndex) != mTaskbarDividerContainer
+                && getChildCount() >= mNumStaticViews + 1) {
+            // Static views with at least one app icon so add divider.
+            addView(mTaskbarDividerContainer, allAppsDividerIndex);
+        }
+    }
+
+    private void updateHotseatItems(ItemInfo[] hotseatItemInfos) {
+        int numViewsAnimated = 0;
+
+        for (ItemInfo hotseatItemInfo : hotseatItemInfos) {
             // Replace any Hotseat views with the appropriate type if it's not already that type.
             final int expectedLayoutResId;
             boolean isCollection = false;
@@ -401,8 +533,8 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
             }
 
             View hotseatView = null;
-            while (nextViewIndex < getChildCount()) {
-                hotseatView = getChildAt(nextViewIndex);
+            while (isNextViewInSection(ItemInfo.class)) {
+                hotseatView = getChildAt(mNextViewIndex);
 
                 // see if the view can be reused
                 if ((hotseatView.getSourceLayoutResId() != expectedLayoutResId)
@@ -443,7 +575,7 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
                 }
                 LayoutParams lp = new LayoutParams(mIconTouchSize, mIconTouchSize);
                 hotseatView.setPadding(mItemPadding, mItemPadding, mItemPadding, mItemPadding);
-                addView(hotseatView, nextViewIndex, lp);
+                addView(hotseatView, mNextViewIndex, lp);
             }
 
             // Apply the Hotseat ItemInfos, or hide the view if there is none for a given index.
@@ -459,34 +591,27 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
             if (enableCursorHoverStates()) {
                 setHoverListenerForIcon(hotseatView);
             }
-            nextViewIndex++;
+            mNextViewIndex++;
         }
 
-        if (mTaskbarDividerContainer != null && !recentTasks.isEmpty()) {
-            addView(mTaskbarDividerContainer, nextViewIndex++);
-            mAddedDividerForRecents = true;
+        while (isNextViewInSection(ItemInfo.class)) {
+            removeAndRecycle(getChildAt(mNextViewIndex));
         }
+    }
 
+    private void updateRecents(List<GroupTask> recentTasks) {
         // At this point, the all apps button has not been added as a child view, but needs to be
         // accounted for when comparing current icon count to max number of icons.
         int nonTaskIconsToBeAdded = 1;
 
         boolean supportsOverflow = Flags.taskbarOverflow();
         int overflowSize = 0;
-        int numberOfSupportedRecents = 0;
         if (supportsOverflow) {
-            for (GroupTask task : recentTasks) {
-                // TODO(b/343289567 and b/316004172): support app pairs and desktop mode.
-                if (!task.supportsMultipleTasks()) {
-                    ++numberOfSupportedRecents;
-                }
-            }
-
-            mIdealNumIcons = nextViewIndex + numberOfSupportedRecents + nonTaskIconsToBeAdded;
+            mIdealNumIcons = mNextViewIndex + recentTasks.size() + nonTaskIconsToBeAdded;
             overflowSize = mIdealNumIcons - mMaxNumIcons;
 
             if (overflowSize > 0 && mTaskbarOverflowView != null) {
-                addView(mTaskbarOverflowView, nextViewIndex++);
+                addView(mTaskbarOverflowView, mNextViewIndex++);
             } else if (mTaskbarOverflowView != null) {
                 mTaskbarOverflowView.clearItems();
             }
@@ -496,9 +621,9 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
         // An extra item needs to be added to overflow button to account for the space taken up by
         // the overflow button.
         final int itemsToAddToOverflow =
-                (overflowSize > 0) ? Math.min(overflowSize + 1, numberOfSupportedRecents) : 0;
+                (overflowSize > 0) ? Math.min(overflowSize + 1, recentTasks.size()) : 0;
         if (overflowSize > 0) {
-            overflownTasks = new ArrayList<Task>(itemsToAddToOverflow);
+            overflownTasks = new ArrayList<>(itemsToAddToOverflow);
         }
 
         // Add Recent/Running icons.
@@ -506,10 +631,6 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
             if (mTaskbarOverflowView != null && overflownTasks != null
                     && overflownTasks.size() < itemsToAddToOverflow) {
                 // TODO(b/343289567 and b/316004172): support app pairs and desktop mode.
-                if (task.supportsMultipleTasks()) {
-                    continue;
-                }
-
                 overflownTasks.add(task.task1);
                 if (overflownTasks.size() == itemsToAddToOverflow) {
                     mTaskbarOverflowView.setItems(overflownTasks);
@@ -534,8 +655,8 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
             }
 
             View recentIcon = null;
-            while (nextViewIndex < getChildCount()) {
-                recentIcon = getChildAt(nextViewIndex);
+            while (isNextViewInSection(GroupTask.class)) {
+                recentIcon = getChildAt(mNextViewIndex);
 
                 // see if the view can be reused
                 if ((recentIcon.getSourceLayoutResId() != expectedLayoutResId)
@@ -549,15 +670,11 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
             }
 
             if (recentIcon == null) {
-                if (isCollection) {
-                    // TODO(b/343289567 and b/316004172): support app pairs and desktop mode.
-                    continue;
-                }
-
+                // TODO(b/343289567 and b/316004172): support app pairs and desktop mode.
                 recentIcon = inflate(expectedLayoutResId);
                 LayoutParams lp = new LayoutParams(mIconTouchSize, mIconTouchSize);
                 recentIcon.setPadding(mItemPadding, mItemPadding, mItemPadding, mItemPadding);
-                addView(recentIcon, nextViewIndex, lp);
+                addView(recentIcon, mNextViewIndex, lp);
             }
 
             if (recentIcon instanceof BubbleTextView btv) {
@@ -567,29 +684,17 @@ public class TaskbarView extends FrameLayout implements FolderIcon.FolderIconPar
             if (enableCursorHoverStates()) {
                 setHoverListenerForIcon(recentIcon);
             }
-            nextViewIndex++;
+            mNextViewIndex++;
         }
 
-        // Remove remaining views
-        while (nextViewIndex < getChildCount()) {
-            removeAndRecycle(getChildAt(nextViewIndex));
+        while (isNextViewInSection(GroupTask.class)) {
+            removeAndRecycle(getChildAt(mNextViewIndex));
         }
+    }
 
-        addView(mAllAppsButtonContainer, mIsRtl ? hotseatItemInfos.length : 0);
-
-        // If there are no recent tasks, add divider after All Apps (unless it's the only view).
-        if (!mAddedDividerForRecents
-                && mTaskbarDividerContainer != null
-                && getChildCount() > 1) {
-            addView(mTaskbarDividerContainer, mIsRtl ? (getChildCount() - 1) : 1);
-        }
-
-
-        if (mActivityContext.getDeviceProfile().isQsbInline) {
-            addView(mQsb, mIsRtl ? getChildCount() : 0);
-            // Always set QSB to invisible after re-adding.
-            mQsb.setVisibility(View.INVISIBLE);
-        }
+    private boolean isNextViewInSection(Class<?> tagClass) {
+        return mNextViewIndex < getChildCount()
+                && tagClass.isInstance(getChildAt(mNextViewIndex).getTag());
     }
 
     /** Binds the GroupTask to the BubbleTextView to be ready to present to the user. */

quickstep/tests/multivalentTests/src/com/android/launcher3/taskbar/TaskbarViewTest.kt

@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.launcher3.taskbar
+
+import android.platform.test.flag.junit.FlagsParameterization
+import android.platform.test.flag.junit.FlagsParameterization.allCombinationsOf
+import android.platform.test.flag.junit.SetFlagsRule
+import com.android.launcher3.Flags.FLAG_TASKBAR_RECENTS_LAYOUT_TRANSITION
+import com.android.launcher3.R
+import com.android.launcher3.taskbar.TaskbarControllerTestUtil.runOnMainSync
+import com.android.launcher3.taskbar.TaskbarIconType.ALL_APPS
+import com.android.launcher3.taskbar.TaskbarIconType.DIVIDER
+import com.android.launcher3.taskbar.TaskbarIconType.HOTSEAT
+import com.android.launcher3.taskbar.TaskbarIconType.RECENT
+import com.android.launcher3.taskbar.TaskbarViewTestUtil.assertThat
+import com.android.launcher3.taskbar.TaskbarViewTestUtil.createHotseatItems
+import com.android.launcher3.taskbar.TaskbarViewTestUtil.createRecents
+import com.android.launcher3.taskbar.rules.TaskbarDeviceEmulationRule
+import com.android.launcher3.taskbar.rules.TaskbarUnitTestRule
+import com.android.launcher3.taskbar.rules.TaskbarUnitTestRule.ForceRtl
+import com.android.launcher3.taskbar.rules.TaskbarWindowSandboxContext
+import com.android.launcher3.util.LauncherMultivalentJUnit.Companion.isRunningInRobolectric
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import platform.test.runner.parameterized.ParameterizedAndroidJunit4
+import platform.test.runner.parameterized.Parameters
+
+@RunWith(ParameterizedAndroidJunit4::class)
+class TaskbarViewTest(deviceName: String, flags: FlagsParameterization) {
+
+    companion object {
+        @JvmStatic
+        @Parameters(name = "{0},{1}")
+        fun getParams(): List<Array<Any>> {
+            val devices =
+                if (isRunningInRobolectric) {
+                    listOf("pixelFoldable2023", "pixelTablet2023")
+                } else {
+                    listOf("onDevice") // Unused.
+                }
+            val flags = allCombinationsOf(FLAG_TASKBAR_RECENTS_LAYOUT_TRANSITION)
+            return devices.flatMap { d -> flags.map { f -> arrayOf(d, f) } } // Cartesian product.
+        }
+    }
+
+    @get:Rule(order = 0) val setFlagsRule = SetFlagsRule(flags)
+    @get:Rule(order = 1) val context = TaskbarWindowSandboxContext.create()
+    @get:Rule(order = 2) val deviceEmulationRule = TaskbarDeviceEmulationRule(context, deviceName)
+    @get:Rule(order = 3) val taskbarUnitTestRule = TaskbarUnitTestRule(this, context)
+
+    private lateinit var taskbarView: TaskbarView
+
+    @Before
+    fun obtainView() {
+        taskbarView = taskbarUnitTestRule.activityContext.dragLayer.findViewById(R.id.taskbar_view)
+    }
+
+    @Test
+    fun testUpdateItems_noItems_hasOnlyAllApps() {
+        runOnMainSync { taskbarView.updateItems(emptyArray(), emptyList()) }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS)
+    }
+
+    @Test
+    fun testUpdateItems_hotseatItems_hasDividerBetweenAllAppsAndHotseat() {
+        runOnMainSync { taskbarView.updateItems(createHotseatItems(2), emptyList()) }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, DIVIDER, HOTSEAT, HOTSEAT)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtlWithHotseatItems_hasDividerBetweenHotseatAndAllApps() {
+        runOnMainSync { taskbarView.updateItems(createHotseatItems(2), emptyList()) }
+        assertThat(taskbarView).hasIconTypes(HOTSEAT, HOTSEAT, DIVIDER, ALL_APPS)
+    }
+
+    @Test
+    fun testUpdateItems_withNullHotseatItem_filtersNullItem() {
+        runOnMainSync {
+            taskbarView.updateItems(arrayOf(*createHotseatItems(2), null), emptyList())
+        }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, DIVIDER, HOTSEAT, HOTSEAT)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtlWithNullHotseatItem_filtersNullItem() {
+        runOnMainSync {
+            taskbarView.updateItems(arrayOf(*createHotseatItems(2), null), emptyList())
+        }
+        assertThat(taskbarView).hasIconTypes(HOTSEAT, HOTSEAT, DIVIDER, ALL_APPS)
+    }
+
+    @Test
+    fun testUpdateItems_recentsItems_hasDividerBetweenAllAppsAndRecents() {
+        runOnMainSync { taskbarView.updateItems(emptyArray(), createRecents(4)) }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, DIVIDER, *RECENT * 4)
+    }
+
+    @Test
+    fun testUpdateItems_hotseatItemsAndRecents_hasDividerBetweenHotseatAndRecents() {
+        runOnMainSync { taskbarView.updateItems(createHotseatItems(3), createRecents(2)) }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, *HOTSEAT * 3, DIVIDER, *RECENT * 2)
+    }
+
+    @Test
+    fun testUpdateItems_addHotseatItem_updatesHotseat() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+            taskbarView.updateItems(createHotseatItems(2), createRecents(1))
+        }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, *HOTSEAT * 2, DIVIDER, RECENT)
+    }
+
+    @Test
+    fun testUpdateItems_removeHotseatItem_updatesHotseat() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(2), createRecents(1))
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+        }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, HOTSEAT, DIVIDER, RECENT)
+    }
+
+    @Test
+    fun testUpdateItems_addRecentsItem_updatesRecents() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+            taskbarView.updateItems(createHotseatItems(1), createRecents(2))
+        }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, HOTSEAT, DIVIDER, *RECENT * 2)
+    }
+
+    @Test
+    fun testUpdateItems_removeRecentsItem_updatesRecents() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(1), createRecents(2))
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+        }
+        assertThat(taskbarView).hasIconTypes(ALL_APPS, HOTSEAT, DIVIDER, RECENT)
+    }
+}

quickstep/tests/multivalentTests/src/com/android/launcher3/taskbar/TaskbarViewTestUtil.kt

@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.launcher3.taskbar
+
+import android.content.ComponentName
+import android.content.Intent
+import android.os.Process
+import com.android.launcher3.model.data.AppInfo
+import com.android.launcher3.model.data.ItemInfo
+import com.android.launcher3.model.data.WorkspaceItemInfo
+import com.android.launcher3.taskbar.TaskbarIconType.ALL_APPS
+import com.android.launcher3.taskbar.TaskbarIconType.DIVIDER
+import com.android.launcher3.taskbar.TaskbarIconType.HOTSEAT
+import com.android.launcher3.taskbar.TaskbarIconType.OVERFLOW
+import com.android.launcher3.taskbar.TaskbarIconType.RECENT
+import com.android.quickstep.util.GroupTask
+import com.android.systemui.shared.recents.model.Task
+import com.android.systemui.shared.recents.model.Task.TaskKey
+import com.google.common.truth.FailureMetadata
+import com.google.common.truth.Subject
+import com.google.common.truth.Truth.assertAbout
+import com.google.common.truth.Truth.assertThat
+
+/** Common utilities for testing [TaskbarView]. */
+object TaskbarViewTestUtil {
+
+    /** Begins an assertion about a [TaskbarView]. */
+    fun assertThat(view: TaskbarView): TaskbarViewSubject {
+        return assertAbout(::TaskbarViewSubject).that(view)
+    }
+
+    /** Creates an array of fake hotseat items. */
+    fun createHotseatItems(size: Int): Array<ItemInfo> {
+        return Array(size) {
+            WorkspaceItemInfo(
+                    AppInfo(TEST_COMPONENT, "Test App $it", Process.myUserHandle(), Intent())
+                )
+                .apply { id = it }
+        }
+    }
+
+    /** Creates a list of fake recent tasks. */
+    fun createRecents(size: Int): List<GroupTask> {
+        return List(size) {
+            GroupTask(
+                Task().apply {
+                    key =
+                        TaskKey(
+                            it,
+                            5,
+                            TEST_INTENT,
+                            TEST_COMPONENT,
+                            Process.myUserHandle().identifier,
+                            System.currentTimeMillis(),
+                        )
+                }
+            )
+        }
+    }
+}
+
+/** A `Truth` [Subject] with extensions for verifying [TaskbarView]. */
+class TaskbarViewSubject(failureMetadata: FailureMetadata, private val view: TaskbarView) :
+    Subject(failureMetadata, view) {
+
+    /** Verifies that the types of icons match [expectedTypes] in order. */
+    fun hasIconTypes(vararg expectedTypes: TaskbarIconType) {
+        val actualTypes =
+            view.iconViews.map {
+                when (it) {
+                    view.allAppsButtonContainer -> ALL_APPS
+                    view.taskbarDividerViewContainer -> DIVIDER
+                    view.taskbarOverflowView -> OVERFLOW
+                    else ->
+                        when (it.tag) {
+                            is ItemInfo -> HOTSEAT
+                            is GroupTask -> RECENT
+                            else -> throw IllegalStateException("Unknown type for $it")
+                        }
+                }
+            }
+        assertThat(actualTypes).containsExactly(*expectedTypes).inOrder()
+    }
+
+    /** Verifies that recents from [startIndex] have IDs that match [expectedIds] in order. */
+    fun hasRecentsOrder(startIndex: Int, expectedIds: List<Int>) {
+        val actualIds =
+            view.iconViews.slice(startIndex..<expectedIds.size).map {
+                assertThat(it.tag).isInstanceOf(GroupTask::class.java)
+                (it.tag as? GroupTask)?.task1?.key?.id
+            }
+        assertThat(actualIds).containsExactlyElementsIn(expectedIds).inOrder()
+    }
+}
+
+/** Types of icons in the [TaskbarView]. */
+enum class TaskbarIconType {
+    ALL_APPS,
+    DIVIDER,
+    HOTSEAT,
+    RECENT,
+    OVERFLOW;
+
+    operator fun times(size: Int) = Array(size) { this }
+}
+
+private const val TEST_PACKAGE = "com.android.launcher3.taskbar"
+private val TEST_COMPONENT = ComponentName(TEST_PACKAGE, "Activity")
+private val TEST_INTENT = Intent().apply { `package` = TEST_PACKAGE }

quickstep/tests/multivalentTests/src/com/android/launcher3/taskbar/TaskbarViewWithLayoutTransitionTest.kt

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.launcher3.taskbar
+
+import android.platform.test.annotations.EnableFlags
+import android.platform.test.flag.junit.SetFlagsRule
+import com.android.launcher3.Flags.FLAG_TASKBAR_RECENTS_LAYOUT_TRANSITION
+import com.android.launcher3.R
+import com.android.launcher3.taskbar.TaskbarControllerTestUtil.runOnMainSync
+import com.android.launcher3.taskbar.TaskbarIconType.ALL_APPS
+import com.android.launcher3.taskbar.TaskbarIconType.DIVIDER
+import com.android.launcher3.taskbar.TaskbarIconType.HOTSEAT
+import com.android.launcher3.taskbar.TaskbarIconType.RECENT
+import com.android.launcher3.taskbar.TaskbarViewTestUtil.assertThat
+import com.android.launcher3.taskbar.TaskbarViewTestUtil.createHotseatItems
+import com.android.launcher3.taskbar.TaskbarViewTestUtil.createRecents
+import com.android.launcher3.taskbar.rules.TaskbarUnitTestRule
+import com.android.launcher3.taskbar.rules.TaskbarUnitTestRule.ForceRtl
+import com.android.launcher3.taskbar.rules.TaskbarWindowSandboxContext
+import com.android.launcher3.util.LauncherMultivalentJUnit
+import com.android.launcher3.util.LauncherMultivalentJUnit.EmulatedDevices
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(LauncherMultivalentJUnit::class)
+@EmulatedDevices(["pixelFoldable2023", "pixelTablet2023"])
+@EnableFlags(FLAG_TASKBAR_RECENTS_LAYOUT_TRANSITION)
+class TaskbarViewWithLayoutTransitionTest {
+
+    @get:Rule(order = 0) val setFlagsRule = SetFlagsRule()
+    @get:Rule(order = 1) val context = TaskbarWindowSandboxContext.create()
+    @get:Rule(order = 2) val taskbarUnitTestRule = TaskbarUnitTestRule(this, context)
+
+    private lateinit var taskbarView: TaskbarView
+
+    @Before
+    fun obtainView() {
+        taskbarView = taskbarUnitTestRule.activityContext.dragLayer.findViewById(R.id.taskbar_view)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_hotseatItems_hasDividerBetweenHotseatAndAllApps() {
+        runOnMainSync { taskbarView.updateItems(createHotseatItems(2), emptyList()) }
+        assertThat(taskbarView).hasIconTypes(*HOTSEAT * 2, DIVIDER, ALL_APPS)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_recentsItems_hasDividerBetweenRecentsAndAllApps() {
+        runOnMainSync { taskbarView.updateItems(emptyArray(), createRecents(4)) }
+        assertThat(taskbarView).hasIconTypes(*RECENT * 4, DIVIDER, ALL_APPS)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_recentsItems_recentsAreReversed() {
+        runOnMainSync { taskbarView.updateItems(emptyArray(), createRecents(4)) }
+        assertThat(taskbarView).hasRecentsOrder(startIndex = 0, expectedIds = listOf(3, 2, 1, 0))
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_hotseatItemsAndRecents_hasDividerBetweenRecentsAndHotseat() {
+        runOnMainSync { taskbarView.updateItems(createHotseatItems(3), createRecents(2)) }
+        assertThat(taskbarView).hasIconTypes(*RECENT * 2, DIVIDER, *HOTSEAT * 3, ALL_APPS)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_addHotseatItem_updatesHotseat() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+            taskbarView.updateItems(createHotseatItems(2), createRecents(1))
+        }
+        assertThat(taskbarView).hasIconTypes(RECENT, DIVIDER, *HOTSEAT * 2, ALL_APPS)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_removeHotseatItem_updatesHotseat() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(2), createRecents(1))
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+        }
+        assertThat(taskbarView).hasIconTypes(RECENT, DIVIDER, HOTSEAT, ALL_APPS)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_addRecentsItem_updatesRecents() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+            taskbarView.updateItems(createHotseatItems(1), createRecents(2))
+        }
+        assertThat(taskbarView).hasIconTypes(*RECENT * 2, DIVIDER, HOTSEAT, ALL_APPS)
+    }
+
+    @Test
+    @ForceRtl
+    fun testUpdateItems_rtl_removeRecentsItem_updatesRecents() {
+        runOnMainSync {
+            taskbarView.updateItems(createHotseatItems(1), createRecents(2))
+            taskbarView.updateItems(createHotseatItems(1), createRecents(1))
+        }
+        assertThat(taskbarView).hasIconTypes(RECENT, DIVIDER, HOTSEAT, ALL_APPS)
+    }
+}