Refactor RecentTasksList ctor to be testable

Made ctor accept more arguments so we can
pass in mock objects for unit testing.

Test: Created RecentsTasksListTest.java, passes
adb shell am instrument -w -r -e debug false -e \
class 'com.android.quickstep.RecentTasksListTest' \
com.google.android.apps.nexuslauncher.tests/androidx.test.runner.AndroidJUnitRunner

Fixes: 135687618
Change-Id: Iffda661e9d5329a2a403060bde674ab81e4e720e
diff --git a/quickstep/src/com/android/quickstep/RecentTasksList.java b/quickstep/src/com/android/quickstep/RecentTasksList.java
index e41dba9..71ce32b 100644
--- a/quickstep/src/com/android/quickstep/RecentTasksList.java
+++ b/quickstep/src/com/android/quickstep/RecentTasksList.java
@@ -20,10 +20,12 @@
 
 import android.annotation.TargetApi;
 import android.app.ActivityManager;
-import android.content.Context;
 import android.os.Build;
 import android.os.Process;
 import android.util.SparseBooleanArray;
+
+import androidx.annotation.VisibleForTesting;
+
 import com.android.launcher3.MainThreadExecutor;
 import com.android.systemui.shared.recents.model.Task;
 import com.android.systemui.shared.system.ActivityManagerWrapper;
@@ -42,6 +44,7 @@
 
     private final KeyguardManagerCompat mKeyguardManager;
     private final MainThreadExecutor mMainThreadExecutor;
+    private final ActivityManagerWrapper mActivityManagerWrapper;
 
     // The list change id, increments as the task list changes in the system
     private int mChangeId;
@@ -52,11 +55,14 @@
 
     ArrayList<Task> mTasks = new ArrayList<>();
 
-    public RecentTasksList(Context context) {
-        mMainThreadExecutor = new MainThreadExecutor();
-        mKeyguardManager = new KeyguardManagerCompat(context);
+
+    public RecentTasksList(MainThreadExecutor mainThreadExecutor,
+            KeyguardManagerCompat keyguardManager, ActivityManagerWrapper activityManagerWrapper) {
+        mMainThreadExecutor = mainThreadExecutor;
+        mKeyguardManager = keyguardManager;
         mChangeId = 1;
-        ActivityManagerWrapper.getInstance().registerTaskStackListener(this);
+        mActivityManagerWrapper = activityManagerWrapper;
+        mActivityManagerWrapper.registerTaskStackListener(this);
     }
 
     /**
@@ -136,12 +142,13 @@
     /**
      * Loads and creates a list of all the recent tasks.
      */
-    private ArrayList<Task> loadTasksInBackground(int numTasks,
+    @VisibleForTesting
+    ArrayList<Task> loadTasksInBackground(int numTasks,
             boolean loadKeysOnly) {
         int currentUserId = Process.myUserHandle().getIdentifier();
         ArrayList<Task> allTasks = new ArrayList<>();
         List<ActivityManager.RecentTaskInfo> rawTasks =
-                ActivityManagerWrapper.getInstance().getRecentTasks(numTasks, currentUserId);
+                mActivityManagerWrapper.getRecentTasks(numTasks, currentUserId);
         // The raw tasks are given in most-recent to least-recent order, we need to reverse it
         Collections.reverse(rawTasks);
 
diff --git a/quickstep/src/com/android/quickstep/RecentsModel.java b/quickstep/src/com/android/quickstep/RecentsModel.java
index 9f12484..650169c 100644
--- a/quickstep/src/com/android/quickstep/RecentsModel.java
+++ b/quickstep/src/com/android/quickstep/RecentsModel.java
@@ -30,11 +30,14 @@
 import android.os.RemoteException;
 import android.util.Log;
 
+import com.android.launcher3.MainThreadExecutor;
 import com.android.launcher3.util.MainThreadInitializedObject;
 import com.android.systemui.shared.recents.ISystemUiProxy;
 import com.android.systemui.shared.recents.model.Task;
 import com.android.systemui.shared.recents.model.ThumbnailData;
 import com.android.systemui.shared.system.ActivityManagerWrapper;
+import com.android.systemui.shared.system.BackgroundExecutor;
+import com.android.systemui.shared.system.KeyguardManagerCompat;
 import com.android.systemui.shared.system.QuickStepContract;
 import com.android.systemui.shared.system.TaskStackChangeListener;
 
@@ -68,7 +71,8 @@
         HandlerThread loaderThread = new HandlerThread("TaskThumbnailIconCache",
                 Process.THREAD_PRIORITY_BACKGROUND);
         loaderThread.start();
-        mTaskList = new RecentTasksList(context);
+        mTaskList = new RecentTasksList(new MainThreadExecutor(),
+                new KeyguardManagerCompat(context), ActivityManagerWrapper.getInstance());
         mIconCache = new TaskIconCache(context, loaderThread.getLooper());
         mThumbnailCache = new TaskThumbnailCache(context, loaderThread.getLooper());
         ActivityManagerWrapper.getInstance().registerTaskStackListener(this);
diff --git a/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java b/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java
new file mode 100644
index 0000000..5fb27bc
--- /dev/null
+++ b/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2019 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.quickstep;
+
+import android.app.ActivityManager;
+
+import androidx.test.filters.SmallTest;
+
+import com.android.launcher3.MainThreadExecutor;
+import com.android.systemui.shared.recents.model.Task;
+import com.android.systemui.shared.system.ActivityManagerWrapper;
+import com.android.systemui.shared.system.KeyguardManagerCompat;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Collections;
+import java.util.List;
+
+import static junit.framework.TestCase.assertNull;
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Matchers.anyInt;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@SmallTest
+public class RecentTasksListTest {
+
+    private ActivityManagerWrapper mockActivityManagerWrapper;
+
+    // Class under test
+    private RecentTasksList mRecentTasksList;
+
+    @Before
+    public void setup() {
+        MainThreadExecutor mockMainThreadExecutor = mock(MainThreadExecutor.class);
+        KeyguardManagerCompat mockKeyguardManagerCompat = mock(KeyguardManagerCompat.class);
+        mockActivityManagerWrapper = mock(ActivityManagerWrapper.class);
+        mRecentTasksList = new RecentTasksList(mockMainThreadExecutor, mockKeyguardManagerCompat,
+                mockActivityManagerWrapper);
+    }
+
+    @Test
+    public void onTaskRemoved_reloadsAllTasks() {
+        mRecentTasksList.onTaskRemoved(0);
+        verify(mockActivityManagerWrapper, times(1))
+                .getRecentTasks(anyInt(), anyInt());
+    }
+
+    @Test
+    public void onTaskStackChanged_doesNotFetchTasks() {
+        mRecentTasksList.onTaskStackChanged();
+        verify(mockActivityManagerWrapper, times(0))
+                .getRecentTasks(anyInt(), anyInt());
+    }
+
+    @Test
+    public void loadTasksInBackground_onlyKeys_noValidTaskDescription() {
+        ActivityManager.RecentTaskInfo recentTaskInfo = new ActivityManager.RecentTaskInfo();
+        when(mockActivityManagerWrapper.getRecentTasks(anyInt(), anyInt()))
+                .thenReturn(Collections.singletonList(recentTaskInfo));
+
+        List<Task> taskList = mRecentTasksList.loadTasksInBackground(Integer.MAX_VALUE, true);
+
+        assertEquals(1, taskList.size());
+        assertNull(taskList.get(0).taskDescription.getLabel());
+    }
+
+    @Test
+    public void loadTasksInBackground_moreThanKeys_hasValidTaskDescription() {
+        String taskDescription = "Wheeee!";
+        ActivityManager.RecentTaskInfo recentTaskInfo = new ActivityManager.RecentTaskInfo();
+        recentTaskInfo.taskDescription = new ActivityManager.TaskDescription(taskDescription);
+        when(mockActivityManagerWrapper.getRecentTasks(anyInt(), anyInt()))
+                .thenReturn(Collections.singletonList(recentTaskInfo));
+
+        List<Task> taskList = mRecentTasksList.loadTasksInBackground(Integer.MAX_VALUE, false);
+
+        assertEquals(1, taskList.size());
+        assertEquals(taskDescription, taskList.get(0).taskDescription.getLabel());
+    }
+}