Highlight row (instead of ripple) when come from search.

- Moved HighlightableAdapter to its own class
- Replaced ripple with blue background
- Bluebackground only stays for 5 seconds. After that it's replaced by
  ?attr/selectableBackground

Misc fixes.

- Fix NPE in UserSettings
- Update char limit on a new string

Change-Id: I4687e54e71fd7b9243f520b7630563df58be23d4
Fixes: 71715698
Fixes: 72761974
Test: robotests

tests/robotests/src/com/android/settings/widget/HighlightablePreferenceGroupAdapterTest.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2018 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.widget;
+
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.graphics.drawable.ColorDrawable;
+import android.support.v7.preference.PreferenceCategory;
+import android.support.v7.preference.PreferenceViewHolder;
+import android.support.v7.widget.RecyclerView;
+import android.view.View;
+
+import com.android.settings.R;
+import com.android.settings.TestConfig;
+import com.android.settings.testutils.SettingsRobolectricTestRunner;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+import org.robolectric.util.ReflectionHelpers;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class HighlightablePreferenceGroupAdapterTest {
+
+    private static final String TEST_KEY = "key";
+
+    @Mock
+    private View mRoot;
+    @Mock
+    private PreferenceCategory mPreferenceCatetory;
+    private Context mContext;
+    private HighlightablePreferenceGroupAdapter mAdapter;
+    private PreferenceViewHolder mViewHolder;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        mContext = RuntimeEnvironment.application;
+        when(mPreferenceCatetory.getContext()).thenReturn(mContext);
+        mAdapter = new HighlightablePreferenceGroupAdapter(mPreferenceCatetory, TEST_KEY,
+                false /* highlighted*/);
+        mViewHolder = PreferenceViewHolder.createInstanceForTests(
+                View.inflate(mContext, R.layout.app_preference_item, null));
+    }
+
+    @Test
+    public void requestHighlight_hasKey_notHighlightedBefore_shouldRequest() {
+        mAdapter.requestHighlight(mRoot, mock(RecyclerView.class));
+
+        verify(mRoot).postDelayed(any(),
+                eq(HighlightablePreferenceGroupAdapter.DELAY_HIGHLIGHT_DURATION_MILLIS));
+    }
+
+    @Test
+    public void requestHighlight_noKey_highlightedBefore_noRecyclerView_shouldNotRequest() {
+        ReflectionHelpers.setField(mAdapter, "mHighlightKey", null);
+        ReflectionHelpers.setField(mAdapter, "mHighlightRequested", false);
+        mAdapter.requestHighlight(mRoot, mock(RecyclerView.class));
+
+        ReflectionHelpers.setField(mAdapter, "mHighlightKey", TEST_KEY);
+        ReflectionHelpers.setField(mAdapter, "mHighlightRequested", true);
+        mAdapter.requestHighlight(mRoot, mock(RecyclerView.class));
+
+        ReflectionHelpers.setField(mAdapter, "mHighlightKey", TEST_KEY);
+        ReflectionHelpers.setField(mAdapter, "mHighlightRequested", false);
+        mAdapter.requestHighlight(mRoot, null /* recyclerView */);
+
+        verifyZeroInteractions(mRoot);
+    }
+
+    @Test
+    public void updateBackground_notHighlightedRow_shouldNotSetHighlightedTag() {
+        ReflectionHelpers.setField(mAdapter, "mHighlightPosition", 10);
+
+        mAdapter.updateBackground(mViewHolder, 0);
+
+        assertThat(mViewHolder.itemView.getTag(R.id.preference_highlighted)).isNull();
+    }
+
+    @Test
+    public void updateBackground_highlight_shouldChangeBackgroundAndSetHighlightedTag() {
+        ReflectionHelpers.setField(mAdapter, "mHighlightPosition", 10);
+
+        mAdapter.updateBackground(mViewHolder, 10);
+        assertThat(mViewHolder.itemView.getBackground()).isInstanceOf(ColorDrawable.class);
+        assertThat(mViewHolder.itemView.getTag(R.id.preference_highlighted)).isEqualTo(true);
+    }
+
+    @Test
+    public void updateBackground_reuseHightlightedRowForNormalRow_shouldResetBackgroundAndTag() {
+        ReflectionHelpers.setField(mAdapter, "mHighlightPosition", 10);
+        mViewHolder.itemView.setTag(R.id.preference_highlighted, true);
+
+        mAdapter.updateBackground(mViewHolder, 0);
+
+        assertThat(mViewHolder.itemView.getBackground()).isNotInstanceOf(ColorDrawable.class);
+        assertThat(mViewHolder.itemView.getTag(R.id.preference_highlighted)).isEqualTo(false);
+    }
+
+}