Add TabLayout UI to on BaseActivity and show it conditionally

There will be a new tablayout UI added to PickActivity on device with
managed user.
Tapping on the UI does nothing at the moment.

Test: atest DocumentsUIGoogleTests:com.android.documentsui.ProfileTabsTest
Bug: 148264331
Change-Id: I727b28dbae7fac59a3da9da7f16ae7c3608a1a0f

9 files changed, 514 insertions, 8 deletions

diff --git a/res/layout/directory_header.xml b/res/layout/directory_header.xml
index 41088c137..45abeb8ba 100644
--- a/res/layout/directory_header.xml
+++ b/res/layout/directory_header.xml
@@ -28,6 +28,12 @@
     <!-- used for search chip. -->
     <include layout="@layout/search_chip_row"/>
 
+    <com.google.android.material.tabs.TabLayout
+        android:id="@+id/tabs"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:visibility="gone"/>
+
     <!-- used for apps row. -->
     <include layout="@layout/apps_row"/>
 
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 07410a432..7c719e644 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -483,4 +483,10 @@
 
     <!-- Content description for deleting search history. [CHAR_LIMIT=60] -->
     <string name="delete_search_history">Delete search history <xliff:g id="text" example="image">%1$s</xliff:g></string>
+
+    <!-- Label of tab to indicate personal directory [CHAR LIMIT=40] -->
+    <string name="personal_tab">Personal</string>
+
+    <!-- Label of tab to indicate work directory [CHAR LIMIT=40] -->
+    <string name="work_tab">Work</string>
 </resources>
diff --git a/src/com/android/documentsui/BaseActivity.java b/src/com/android/documentsui/BaseActivity.java
index a44cec513..afa141317 100644
--- a/src/com/android/documentsui/BaseActivity.java
+++ b/src/com/android/documentsui/BaseActivity.java
@@ -75,6 +75,7 @@ import com.android.documentsui.sorting.SortController;
 import com.android.documentsui.sorting.SortModel;
 
 import com.google.android.material.appbar.AppBarLayout;
+import com.google.android.material.tabs.TabLayout;
 
 import java.util.ArrayList;
 import java.util.Date;
@@ -95,7 +96,6 @@ public abstract class BaseActivity
     protected Injector<?> mInjector;
 
     protected ProvidersCache mProviders;
-    protected UserIdManager mUserIdManager;
     protected DocumentsAccess mDocs;
     protected DrawerController mDrawer;
 
@@ -153,7 +153,6 @@ public abstract class BaseActivity
         mDrawer = DrawerController.create(this, mInjector.config);
         Metrics.logActivityLaunch(mState, intent);
 
-        mUserIdManager = DocumentsApplication.getUserIdManager(this);
         mProviders = DocumentsApplication.getProvidersCache(this);
         mDocs = DocumentsAccess.create(this);
 
@@ -162,8 +161,11 @@ public abstract class BaseActivity
 
         Breadcrumb breadcrumb = findViewById(R.id.horizontal_breadcrumb);
         assert(breadcrumb != null);
+        TabLayout profileTabs = findViewById(R.id.tabs);
+        assert (profileTabs != null);
 
-        mNavigator = new NavigationViewManager(this, mDrawer, mState, this, breadcrumb);
+        mNavigator = new NavigationViewManager(this, mDrawer, mState, this, breadcrumb,
+                profileTabs, DocumentsApplication.getUserIdManager(this));
         SearchManagerListener searchListener = new SearchManagerListener() {
             /**
              * Called when search results changed. Refreshes the content of the directory. It
@@ -739,6 +741,11 @@ public abstract class BaseActivity
     }
 
     @Override
+    public boolean isSearching() {
+        return mSearchManager.isSearching();
+    }
+
+    @Override
     public RootInfo getCurrentRoot() {
         RootInfo root = mState.stack.getRoot();
         if (root != null) {
diff --git a/src/com/android/documentsui/NavigationViewManager.java b/src/com/android/documentsui/NavigationViewManager.java
index d07851238..aca8c31b5 100644
--- a/src/com/android/documentsui/NavigationViewManager.java
+++ b/src/com/android/documentsui/NavigationViewManager.java
@@ -29,13 +29,13 @@ import android.view.ViewOutlineProvider;
 import androidx.annotation.Nullable;
 import androidx.appcompat.widget.Toolbar;
 
-import com.android.documentsui.R;
 import com.android.documentsui.base.RootInfo;
 import com.android.documentsui.base.State;
 import com.android.documentsui.dirlist.AnimationView;
 
 import com.google.android.material.appbar.AppBarLayout;
 import com.google.android.material.appbar.CollapsingToolbarLayout;
+import com.google.android.material.tabs.TabLayout;
 
 import java.util.function.IntConsumer;
 
@@ -51,6 +51,7 @@ public class NavigationViewManager {
     private final State mState;
     private final NavigationViewManager.Environment mEnv;
     private final Breadcrumb mBreadcrumb;
+    private final ProfileTabs mProfileTabs;
     private final View mSearchBarView;
     private final CollapsingToolbarLayout mCollapsingBarLayout;
     private final Drawable mDefaultActionBarBackground;
@@ -62,7 +63,9 @@ public class NavigationViewManager {
             DrawerController drawer,
             State state,
             NavigationViewManager.Environment env,
-            Breadcrumb breadcrumb) {
+            Breadcrumb breadcrumb,
+            TabLayout tabLayout,
+            UserIdManager userIdManager) {
 
         mToolbar = activity.findViewById(R.id.toolbar);
         mDrawer = drawer;
@@ -70,6 +73,7 @@ public class NavigationViewManager {
         mEnv = env;
         mBreadcrumb = breadcrumb;
         mBreadcrumb.setup(env, state, this::onNavigationItemSelected);
+        mProfileTabs = new ProfileTabs(tabLayout, mState, userIdManager, mEnv);
 
         mToolbar.setNavigationOnClickListener(
                 new View.OnClickListener() {
@@ -122,6 +126,7 @@ public class NavigationViewManager {
     public void update() {
         updateScrollFlag();
         updateToolbar();
+        mProfileTabs.updateView();
 
         // TODO: Looks to me like this block is never getting hit.
         if (mEnv.isSearchExpanded()) {
@@ -214,5 +219,6 @@ public class NavigationViewManager {
         @Deprecated  // Use CommonAddones#refreshCurrentRootAndDirectory
         void refreshCurrentRootAndDirectory(int animation);
         boolean isSearchExpanded();
+        boolean isSearching();
     }
 }
diff --git a/src/com/android/documentsui/ProfileTabs.java b/src/com/android/documentsui/ProfileTabs.java
new file mode 100644
index 000000000..24a36b2b7
--- /dev/null
+++ b/src/com/android/documentsui/ProfileTabs.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2020 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.documentsui;
+
+import static androidx.core.util.Preconditions.checkNotNull;
+
+import android.view.View;
+
+import androidx.annotation.VisibleForTesting;
+
+import com.android.documentsui.base.State;
+import com.android.documentsui.base.UserId;
+
+import com.google.android.material.tabs.TabLayout;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A manager class to control UI on a {@link TabLayout} for cross-profile purpose.
+ */
+public class ProfileTabs {
+
+    private final TabLayout mTabs;
+    private final State mState;
+    private final NavigationViewManager.Environment mEnv;
+    private final UserIdManager mUserIdManager;
+    private List<UserId> mUserIds;
+
+    public ProfileTabs(TabLayout tabLayout, State state, UserIdManager userIdManager,
+            NavigationViewManager.Environment env) {
+        mTabs = checkNotNull(tabLayout);
+        mState = checkNotNull(state);
+        mEnv = checkNotNull(env);
+        mUserIdManager = checkNotNull(userIdManager);
+        mTabs.removeAllTabs();
+        mUserIds = Collections.singletonList(UserId.CURRENT_USER);
+    }
+
+    /**
+     * Update the tab layout based on conditions.
+     */
+    public void updateView() {
+        updateTabsIfNeeded();
+        mTabs.setVisibility(shouldShow() ? View.VISIBLE : View.GONE);
+    }
+
+    private void updateTabsIfNeeded() {
+        List<UserId> userIds = mUserIdManager.getUserIds();
+        // Add tabs if the userIds is not equals to cached mUserIds.
+        // Given that mUserIds was initialized with only the current user, if getUserIds()
+        // returns just the current user, we don't need to do anything on the tab layout.
+        if (!userIds.equals(mUserIds)) {
+            mUserIds = userIds;
+            mTabs.removeAllTabs();
+            if (mUserIds.size() > 1) {
+                mTabs.addTab(createTab(R.string.personal_tab, mUserIdManager.getSystemUser()));
+                mTabs.addTab(createTab(R.string.work_tab, mUserIdManager.getManagedUser()));
+            }
+        }
+    }
+
+    /**
+     * Returns the user represented by the selected tab. If there is no tab, return the
+     * current user.
+     */
+    @VisibleForTesting
+    public UserId getSelectedUser() {
+        if (mTabs.getTabCount() > 1 && mTabs.getSelectedTabPosition() >= 0) {
+            return (UserId) mTabs.getTabAt(mTabs.getSelectedTabPosition()).getTag();
+        }
+        return UserId.CURRENT_USER;
+    }
+
+    private boolean shouldShow() {
+        // Only show tabs when:
+        // 1. state supports cross profile, and
+        // 2. more than one tab, and
+        // 3. not in search mode, and
+        // 4. not in sub-folder, and
+        // 5. the root supports cross profile.
+        return mState.supportsCrossProfile()
+                && mTabs.getTabCount() > 1
+                && !mEnv.isSearching()
+                && mState.stack.size() <= 1
+                && mState.stack.getRoot() != null && mState.stack.getRoot().supportsCrossProfile();
+    }
+
+    private TabLayout.Tab createTab(int resId, UserId userId) {
+        return mTabs.newTab().setText(resId).setTag(userId);
+    }
+}
diff --git a/src/com/android/documentsui/UserIdManager.java b/src/com/android/documentsui/UserIdManager.java
index d489712af..03fb73309 100644
--- a/src/com/android/documentsui/UserIdManager.java
+++ b/src/com/android/documentsui/UserIdManager.java
@@ -21,13 +21,17 @@ import static androidx.core.util.Preconditions.checkNotNull;
 import static com.android.documentsui.base.SharedMinimal.DEBUG;
 
 import android.Manifest;
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.pm.PackageManager;
 import android.os.Build;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.util.Log;
 
+import androidx.annotation.GuardedBy;
 import androidx.annotation.VisibleForTesting;
 import androidx.core.os.BuildCompat;
 
@@ -36,19 +40,30 @@ import com.android.documentsui.base.UserId;
 import java.util.ArrayList;
 import java.util.List;
 
-
 /**
  * Interface to query user ids.
  */
 public interface UserIdManager {
 
     /**
-     * Returns the {@UserId} of each profile which should be queried for documents. This
-     * will always include {@link UserId#CURRENT_USER}.
+     * Returns the {@UserId} of each profile which should be queried for documents. This will always
+     * include {@link UserId#CURRENT_USER}.
      */
     List<UserId> getUserIds();
 
     /**
+     * Returns the system user from {@link #getUserIds()} if the list at least 2 users. Otherwise,
+     * returns null.
+     */
+    UserId getSystemUser();
+
+    /**
+     * Returns the managed user from {@link #getUserIds()} if the list at least 2 users. Otherwise,
+     * returns null.
+     */
+    UserId getManagedUser();
+
+    /**
      * Creates an implementation of {@link UserIdManager}.
      */
     static UserIdManager create(Context context) {
@@ -68,6 +83,23 @@ public interface UserIdManager {
         private final UserId mCurrentUser;
         private final boolean mIsDeviceSupported;
 
+        @GuardedBy("mUserIds")
+        private final List<UserId> mUserIds = new ArrayList<>();
+        @GuardedBy("mUserIds")
+        private UserId mSystemUser = null;
+        @GuardedBy("mUserIds")
+        private UserId mManagedUser = null;
+
+        private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
+
+            @Override
+            public void onReceive(Context context, Intent intent) {
+                synchronized (mUserIds) {
+                    mUserIds.clear();
+                }
+            }
+        };
+
         private RuntimeUserIdManager(Context context) {
             this(context, UserId.CURRENT_USER,
                     ENABLE_MULTI_PROFILES && isDeviceSupported(context));
@@ -78,10 +110,45 @@ public interface UserIdManager {
             mContext = context.getApplicationContext();
             mCurrentUser = checkNotNull(currentUser);
             mIsDeviceSupported = isDeviceSupported;
+
+
+            IntentFilter filter = new IntentFilter();
+            filter.addAction(Intent.ACTION_USER_ADDED);
+            filter.addAction(Intent.ACTION_USER_REMOVED);
+            mContext.registerReceiver(mIntentReceiver, filter);
         }
 
         @Override
         public List<UserId> getUserIds() {
+            synchronized (mUserIds) {
+                if (mUserIds.isEmpty()) {
+                    mUserIds.addAll(getUserIdsInternal());
+                }
+            }
+            return mUserIds;
+        }
+
+        @Override
+        public UserId getSystemUser() {
+            synchronized (mUserIds) {
+                if (mUserIds.isEmpty()) {
+                    getUserIds();
+                }
+            }
+            return mSystemUser;
+        }
+
+        @Override
+        public UserId getManagedUser() {
+            synchronized (mUserIds) {
+                if (mUserIds.isEmpty()) {
+                    getUserIds();
+                }
+            }
+            return mManagedUser;
+        }
+
+        public List<UserId> getUserIdsInternal() {
             final List<UserId> result = new ArrayList<>();
             result.add(mCurrentUser);
 
@@ -103,6 +170,7 @@ public interface UserIdManager {
 
             UserId systemUser = null;
             UserId managedUser = null;
+
             for (UserHandle userHandle : userProfiles) {
                 if (userHandle.isSystem()) {
                     systemUser = UserId.of(userHandle);
@@ -136,6 +204,8 @@ public interface UserIdManager {
                             + (systemUser != null));
                 }
             }
+            mSystemUser = systemUser;
+            mManagedUser = managedUser;
             return result;
         }
 
diff --git a/src/com/android/documentsui/base/RootInfo.java b/src/com/android/documentsui/base/RootInfo.java
index 0f9dabcf6..4f0123578 100644
--- a/src/com/android/documentsui/base/RootInfo.java
+++ b/src/com/android/documentsui/base/RootInfo.java
@@ -327,6 +327,10 @@ public class RootInfo implements Durable, Parcelable, Comparable<RootInfo> {
                 || derivedType == TYPE_SD;
     }
 
+    public boolean isPhoneStorage() {
+        return derivedType == TYPE_LOCAL;
+    }
+
     public boolean hasSettings() {
         return (flags & Root.FLAG_HAS_SETTINGS) != 0;
     }
@@ -375,6 +379,13 @@ public class RootInfo implements Durable, Parcelable, Comparable<RootInfo> {
         return (flags & Root.FLAG_REMOVABLE_USB) != 0;
     }
 
+    /**
+     * Returns true if this root supports cross profile.
+     */
+    public boolean supportsCrossProfile() {
+        return isLibrary() || isDownloads() || isPhoneStorage();
+    }
+
     private Drawable loadMimeTypeIcon(Context context) {
         switch (derivedType) {
             case TYPE_IMAGES:
diff --git a/tests/unit/com/android/documentsui/ProfileTabsTest.java b/tests/unit/com/android/documentsui/ProfileTabsTest.java
new file mode 100644
index 000000000..dc8f0f9cb
--- /dev/null
+++ b/tests/unit/com/android/documentsui/ProfileTabsTest.java
@@ -0,0 +1,258 @@
+/*
+ * Copyright (C) 2020 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.documentsui;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.os.UserHandle;
+import android.view.LayoutInflater;
+import android.view.View;
+
+import androidx.test.InstrumentationRegistry;
+
+import com.android.documentsui.base.RootInfo;
+import com.android.documentsui.base.State;
+import com.android.documentsui.base.UserId;
+import com.android.documentsui.testing.TestEnv;
+import com.android.documentsui.testing.TestProvidersAccess;
+
+import com.google.android.collect.Lists;
+import com.google.android.material.tabs.TabLayout;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class ProfileTabsTest {
+
+    private final UserId systemUser = UserId.of(UserHandle.SYSTEM);
+    private final UserId managedUser = UserId.of(100);
+
+    private ProfileTabs mProfileTabs;
+
+    private Context mContext;
+    private TabLayout mTabLayout;
+    private TestEnvironment mTestEnv;
+    private State mState;
+    private TestUserIdManager mTestUserIdManager;
+
+    @Before
+    public void setUp() {
+        TestEnv.create();
+        mContext = InstrumentationRegistry.getInstrumentation().getTargetContext();
+        mContext.setTheme(R.style.DocumentsTheme);
+        mContext.getTheme().applyStyle(R.style.DocumentsDefaultTheme, false);
+        LayoutInflater layoutInflater = LayoutInflater.from(mContext);
+        mState = new State();
+        mState.action = State.ACTION_GET_CONTENT;
+        mState.stack.changeRoot(TestProvidersAccess.DOWNLOADS);
+        mState.stack.push(TestEnv.FOLDER_0);
+        View view = layoutInflater.inflate(R.layout.directory_header, null);
+
+        mTabLayout = view.findViewById(R.id.tabs);
+        mTestEnv = new TestEnvironment();
+        mTestEnv.isSearching = false;
+
+        mTestUserIdManager = new TestUserIdManager();
+    }
+
+    @Test
+    public void testUpdateView_singleUser_shouldHide() {
+        initializeWithUsers(systemUser);
+
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+        assertThat(mTabLayout.getTabCount()).isEqualTo(0);
+    }
+
+    @Test
+    public void testUpdateView_twoUsers_shouldShow() {
+        initializeWithUsers(systemUser, managedUser);
+
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.VISIBLE);
+        assertThat(mTabLayout.getTabCount()).isEqualTo(2);
+
+        TabLayout.Tab tab1 = mTabLayout.getTabAt(0);
+        assertThat(tab1.getTag()).isEqualTo(systemUser);
+        assertThat(tab1.getText()).isEqualTo(mContext.getString(R.string.personal_tab));
+
+        TabLayout.Tab tab2 = mTabLayout.getTabAt(1);
+        assertThat(tab2.getTag()).isEqualTo(managedUser);
+        assertThat(tab2.getText()).isEqualTo(mContext.getString(R.string.work_tab));
+    }
+
+    @Test
+    public void testUpdateView_twoUsers_browse_shouldHide() {
+        initializeWithUsers(systemUser, managedUser);
+
+        mState.action = State.ACTION_BROWSE;
+        mProfileTabs.updateView();
+
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+    }
+
+    @Test
+    public void testUpdateView_twoUsers_subFolder_shouldHide() {
+        initializeWithUsers(systemUser, managedUser);
+
+        // Push 1 more folder. Now the stack has size of 2.
+        mState.stack.push(TestEnv.FOLDER_1);
+
+        mProfileTabs.updateView();
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+        assertThat(mTabLayout.getTabCount()).isEqualTo(2);
+    }
+
+    @Test
+    public void testUpdateView_twoUsers_recents_subFolder_shouldHide() {
+        initializeWithUsers(systemUser, managedUser);
+
+        mState.stack.changeRoot(TestProvidersAccess.RECENTS);
+        // This(stack of size 2 in Recents) may not happen in real world.
+        mState.stack.push((TestEnv.FOLDER_0));
+
+        mProfileTabs.updateView();
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+        assertThat(mTabLayout.getTabCount()).isEqualTo(2);
+    }
+
+    @Test
+    public void testUpdateView_twoUsers_thirdParty_shouldHide() {
+        initializeWithUsers(systemUser, managedUser);
+
+        mState.stack.changeRoot(TestProvidersAccess.PICKLES);
+        mState.stack.push((TestEnv.FOLDER_0));
+
+        mProfileTabs.updateView();
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+        assertThat(mTabLayout.getTabCount()).isEqualTo(2);
+    }
+
+    @Test
+    public void testUpdateView_twoUsers_isSearching_shouldHide() {
+        mTestEnv.isSearching = true;
+        initializeWithUsers(systemUser, managedUser);
+
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+        assertThat(mTabLayout.getTabCount()).isEqualTo(2);
+    }
+
+    @Test
+    public void testUpdateView_getSelectedUser_afterUsersChanged() {
+        initializeWithUsers(systemUser, managedUser);
+        mProfileTabs.updateView();
+        mTabLayout.selectTab(mTabLayout.getTabAt(1));
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.VISIBLE);
+        assertThat(mProfileTabs.getSelectedUser()).isEqualTo(managedUser);
+
+        mTestUserIdManager.userIds = Collections.singletonList(systemUser);
+        mProfileTabs.updateView();
+        assertThat(mTabLayout.getVisibility()).isEqualTo(View.GONE);
+        assertThat(mProfileTabs.getSelectedUser()).isEqualTo(systemUser);
+    }
+
+    @Test
+    public void testgetSelectedUser_twoUsers() {
+        initializeWithUsers(systemUser, managedUser);
+
+        mTabLayout.selectTab(mTabLayout.getTabAt(0));
+        assertThat(mProfileTabs.getSelectedUser()).isEqualTo(systemUser);
+
+        mTabLayout.selectTab(mTabLayout.getTabAt(1));
+        assertThat(mProfileTabs.getSelectedUser()).isEqualTo(managedUser);
+    }
+
+    @Test
+    public void testgetSelectedUser_singleUsers() {
+        initializeWithUsers(systemUser);
+
+        assertThat(mProfileTabs.getSelectedUser()).isEqualTo(systemUser);
+    }
+
+    private void initializeWithUsers(UserId... userIds) {
+        mTestUserIdManager.userIds = Lists.newArrayList(userIds);
+        for (UserId userId : userIds) {
+            if (userId.isSystem()) {
+                mTestUserIdManager.systemUser = userId;
+            } else {
+                mTestUserIdManager.managedUser = userId;
+            }
+        }
+
+        mProfileTabs = new ProfileTabs(mTabLayout, mState, mTestUserIdManager, mTestEnv);
+        mProfileTabs.updateView();
+    }
+
+    /**
+     * A test implementation of {@link NavigationViewManager.Environment}.
+     */
+    private static class TestEnvironment implements NavigationViewManager.Environment {
+
+        public boolean isSearching = false;
+
+        @Override
+        public RootInfo getCurrentRoot() {
+            throw new UnsupportedOperationException("not implemented");
+        }
+
+        @Override
+        public String getDrawerTitle() {
+            throw new UnsupportedOperationException("not implemented");
+        }
+
+        @Override
+        public void refreshCurrentRootAndDirectory(int animation) {
+            throw new UnsupportedOperationException("not implemented");
+        }
+
+        @Override
+        public boolean isSearchExpanded() {
+            throw new UnsupportedOperationException("not implemented");
+        }
+
+        @Override
+        public boolean isSearching() {
+            return isSearching;
+        }
+
+    }
+
+    private static class TestUserIdManager implements UserIdManager {
+        List<UserId> userIds = new ArrayList<>();
+        UserId systemUser = null;
+        UserId managedUser = null;
+
+        @Override
+        public List<UserId> getUserIds() {
+            return userIds;
+        }
+
+        @Override
+        public UserId getSystemUser() {
+            return systemUser;
+        }
+
+        @Override
+        public UserId getManagedUser() {
+            return managedUser;
+        }
+    }
+}
+
diff --git a/tests/unit/com/android/documentsui/UserIdManagerTest.java b/tests/unit/com/android/documentsui/UserIdManagerTest.java
index 78337a7e2..1ca3c5b50 100644
--- a/tests/unit/com/android/documentsui/UserIdManagerTest.java
+++ b/tests/unit/com/android/documentsui/UserIdManagerTest.java
@@ -154,6 +154,42 @@ public class UserIdManagerTest {
         }
     }
 
+    @Test
+    public void testGetUserIds_systemUserAndManagedUser_returnCachedList() {
+        // Returns the both if there are system and managed users.
+        UserId currentUser = UserId.of(systemUser);
+        initializeUserIdManager(currentUser, Arrays.asList(systemUser, managedUser1));
+        assertThat(mUserIdManager.getUserIds()).isSameAs(mUserIdManager.getUserIds());
+    }
+
+    @Test
+    public void testGetManagedUser_contains() {
+        UserId currentUser = UserId.of(systemUser);
+        initializeUserIdManager(currentUser, Arrays.asList(systemUser, managedUser1));
+        assertThat(mUserIdManager.getManagedUser()).isEqualTo(UserId.of(managedUser1));
+    }
+
+    @Test
+    public void testGetSystemUser_contains() {
+        UserId currentUser = UserId.of(systemUser);
+        initializeUserIdManager(currentUser, Arrays.asList(systemUser, managedUser1));
+        assertThat(mUserIdManager.getSystemUser()).isEqualTo(UserId.of(systemUser));
+    }
+
+    @Test
+    public void testGetSystemUser_singletonList_returnNull() {
+        UserId currentUser = UserId.of(systemUser);
+        initializeUserIdManager(currentUser, Arrays.asList(systemUser));
+        assertThat(mUserIdManager.getSystemUser()).isNull();
+    }
+
+    @Test
+    public void testGetManagedUser_missing() {
+        UserId currentUser = UserId.of(systemUser);
+        initializeUserIdManager(currentUser, Arrays.asList(systemUser, nonManagedUser1));
+        assertThat(mUserIdManager.getManagedUser()).isNull();
+    }
+
     private void initializeUserIdManager(UserId current, List<UserHandle> usersOnDevice) {
         when(mockUserManager.getUserProfiles()).thenReturn(usersOnDevice);
         mUserIdManager = new UserIdManager.RuntimeUserIdManager(mockContext, current, true);