Add FutureTask approach in DashboardFragment

- Use the multiple tasks to enhance the controllers loading.

Bug: 137558156
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.dashboard
Change-Id: I629ff5dc81347cddf9762a87015b9b86b6a46e50

tests/robotests/src/com/android/settings/dashboard/ControllerTaskTest.java

@@ -0,0 +1,124 @@
+/*
+ * 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.settings.dashboard;
+
+import static com.android.settingslib.core.instrumentation.Instrumentable.METRICS_CATEGORY_UNKNOWN;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
+import android.content.Context;
+
+import androidx.preference.Preference;
+import androidx.preference.PreferenceManager;
+import androidx.preference.PreferenceScreen;
+
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class ControllerTaskTest {
+    private static final String KEY = "my_key";
+
+    private Context mContext;
+    private PreferenceScreen mScreen;
+    private TestPreferenceController mTestController;
+    private ControllerTask mControllerTask;
+
+    @Before
+    public void setUp() {
+        mContext = RuntimeEnvironment.application;
+        final PreferenceManager preferenceManager = new PreferenceManager(mContext);
+        mScreen = preferenceManager.createPreferenceScreen(mContext);
+        mTestController = spy(new TestPreferenceController(mContext));
+        mControllerTask = new ControllerTask(mTestController, mScreen, null /* metricsFeature */,
+                METRICS_CATEGORY_UNKNOWN);
+    }
+
+    @Test
+    public void doRun_controlNotAvailable_noRunUpdateState() {
+        mTestController.setAvailable(false);
+
+        mControllerTask.run();
+
+        verify(mTestController, never()).updateState(any(Preference.class));
+    }
+
+    @Test
+    public void doRun_emptyKey_noRunUpdateState() {
+        mTestController.setKey("");
+
+        mControllerTask.run();
+
+        verify(mTestController, never()).updateState(any(Preference.class));
+    }
+
+    @Test
+    public void doRun_preferenceNotExist_noRunUpdateState() {
+        mTestController.setKey(KEY);
+
+        mControllerTask.run();
+
+        verify(mTestController, never()).updateState(any(Preference.class));
+    }
+
+    @Test
+    public void doRun_executeUpdateState() {
+        mTestController.setKey(KEY);
+        final Preference preference = new Preference(mContext);
+        preference.setKey(KEY);
+        mScreen.addPreference(preference);
+
+        mControllerTask.run();
+
+        verify(mTestController).updateState(any(Preference.class));
+    }
+
+    static class TestPreferenceController extends AbstractPreferenceController {
+        private boolean mAvailable;
+        private String mKey;
+
+        TestPreferenceController(Context context) {
+            super(context);
+            mAvailable = true;
+        }
+
+        @Override
+        public boolean isAvailable() {
+            return mAvailable;
+        }
+
+        @Override
+        public String getPreferenceKey() {
+            return mKey;
+        }
+
+        void setAvailable(boolean available) {
+            mAvailable = available;
+        }
+
+        void setKey(String key) {
+            mKey = key;
+        }
+    }
+}