Implement the missing PreferenceControllerMixin interface

Change-Id: I0bb28cf9d2ec24629485a754778faddcbc8f9fdb
Fixes: 68716631
Test: atest PreferenceControllerContractTest

src/com/android/settings/display/ShowOperatorNamePreferenceController.java

@@ -19,10 +19,11 @@ import android.support.v14.preference.SwitchPreference;
 import android.support.v7.preference.Preference;
 
 import com.android.settings.R;
+import com.android.settings.core.PreferenceControllerMixin;
 import com.android.settingslib.core.AbstractPreferenceController;
 
 public class ShowOperatorNamePreferenceController extends AbstractPreferenceController
-        implements Preference.OnPreferenceChangeListener {
+        implements PreferenceControllerMixin, Preference.OnPreferenceChangeListener {
 
     private static final String KEY_SHOW_OPERATOR_NAME = "show_operator_name";
 

tests/unit/src/com/android/settings/core/PreferenceControllerContractTest.java

@@ -0,0 +1,86 @@
+/*
+ * 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.core;
+
+import static junit.framework.Assert.fail;
+
+import android.content.Context;
+import android.provider.SearchIndexableResource;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.MediumTest;
+import android.support.test.runner.AndroidJUnit4;
+import android.util.ArraySet;
+
+import com.android.settings.search.DatabaseIndexingUtils;
+import com.android.settings.search.Indexable;
+import com.android.settings.search.SearchIndexableResources;
+import com.android.settingslib.core.AbstractPreferenceController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.List;
+import java.util.Set;
+
+@RunWith(AndroidJUnit4.class)
+@MediumTest
+public class PreferenceControllerContractTest {
+
+    private Context mContext;
+
+    @Before
+    public void setUp() {
+        mContext = InstrumentationRegistry.getTargetContext();
+    }
+
+    @Test
+    public void controllersInSearchShouldImplementPreferenceControllerMixin() {
+        final Set<String> errorClasses = new ArraySet<>();
+
+        for (SearchIndexableResource page : SearchIndexableResources.values()) {
+            final Class<?> clazz = DatabaseIndexingUtils.getIndexableClass(page.className);
+
+            final Indexable.SearchIndexProvider provider =
+                    DatabaseIndexingUtils.getSearchIndexProvider(clazz);
+            if (provider == null) {
+                continue;
+            }
+
+            final List<AbstractPreferenceController> controllers =
+                    provider.getPreferenceControllers(mContext);
+            if (controllers == null) {
+                continue;
+            }
+            for (AbstractPreferenceController controller : controllers) {
+                if (!(controller instanceof PreferenceControllerMixin)) {
+                    errorClasses.add(controller.getClass().getName());
+                }
+            }
+        }
+
+        if (!errorClasses.isEmpty()) {
+            final StringBuilder errorMessage = new StringBuilder()
+                    .append("Each preference must implement PreferenceControllerMixin, ")
+                    .append("the following classes don't:\n");
+            for (String c : errorClasses) {
+                errorMessage.append(c).append("\n");
+            }
+            fail(errorMessage.toString());
+        }
+    }
+}

tests/unit/src/com/android/settings/core/UniquePreferenceTest.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.android.settings;
+package com.android.settings.core;
 
 import static junit.framework.Assert.fail;