Add pairing preference

This preference lives in paired category. When clicked, it will
go to the pairing page.

Bug: 35877041
Test: RunSettingsRoboTests
Change-Id: I64706c49c8d303a494d4c1827e1f86b59effd54c

tests/robotests/src/com/android/settings/bluetooth/BluetoothPairingPreferenceControllerTest.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2017 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.bluetooth;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.when;
+
+import android.app.FragmentManager;
+import android.app.FragmentTransaction;
+import android.content.Context;
+import android.support.v14.preference.PreferenceFragment;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+
+import com.android.settings.SettingsRobolectricTestRunner;
+import com.android.settings.TestConfig;
+import com.android.settings.R;
+import com.android.settingslib.bluetooth.LocalBluetoothAdapter;
+import com.android.settingslib.core.lifecycle.Lifecycle;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Answers;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class BluetoothPairingPreferenceControllerTest {
+
+    private Context mContext;
+    @Mock(answer = Answers.RETURNS_DEEP_STUBS)
+    private PreferenceFragment mFragment;
+    @Mock
+    private Lifecycle mLifecycle;
+    @Mock
+    private LocalBluetoothAdapter mLocalAdapter;
+    @Mock
+    private FragmentManager mFragmentManager;
+    @Mock
+    private FragmentTransaction mFragmentTransaction;
+    @Mock
+    private PreferenceScreen mPreferenceScreen;
+    private Preference mPreference;
+
+    private BluetoothPairingPreferenceController mController;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        mContext = RuntimeEnvironment.application;
+        when(mFragment.getPreferenceScreen().getContext()).thenReturn(mContext);
+
+        mController = new BluetoothPairingPreferenceController(mContext, mFragment);
+    }
+
+    @Test
+    public void testCreateBluetoothPairingPreference() {
+        Preference pref = mController.createBluetoothPairingPreference();
+
+        assertThat(pref.getKey()).isEqualTo(BluetoothPairingPreferenceController.KEY_PAIRING);
+        assertThat(pref.getIcon()).isEqualTo(mContext.getDrawable(R.drawable.ic_add));
+        assertThat(pref.getTitle()).isEqualTo(
+                mContext.getString(R.string.bluetooth_pairing_pref_title));
+    }
+}