Display Private DNS status in preference summary

Also: fix a bug where the actual current mode is not read correctly
from settings on initialization.

Test: as follows
    - built, flashed, booted
    - manual test behaves as expected
    - make -j50 RunSettingsRoboTests ROBOTEST_FILTER=PrivateDnsModeDialogPreferenceTest passes
    - make -j50 RunSettingsRoboTests ROBOTEST_FILTER=PrivateDnsPreferenceControllerTest passes
Bug: 34953048
Bug: 64133961
Change-Id: I0b845b3894a47b837abf5de273d1ada642ef5a23

tests/robotests/src/com/android/settings/network/PrivateDnsModeDialogPreferenceTest.java

@@ -111,8 +111,10 @@ public class PrivateDnsModeDialogPreferenceTest {
 
     @Test
     public void testOnBindDialogView_containsCorrectData() {
+        // Don't set settings to the default value ("opportunistic") as that
+        // risks masking failure to read the mode from settings.
         Settings.Global.putString(mContext.getContentResolver(),
-                PrivateDnsModeDialogPreference.MODE_KEY, PRIVATE_DNS_MODE_OPPORTUNISTIC);
+                PrivateDnsModeDialogPreference.MODE_KEY, PRIVATE_DNS_MODE_OFF);
         Settings.Global.putString(mContext.getContentResolver(),
                 PrivateDnsModeDialogPreference.HOSTNAME_KEY, HOST_NAME);
 
@@ -123,7 +125,7 @@ public class PrivateDnsModeDialogPreferenceTest {
 
         assertThat(mPreference.mEditText.getText().toString()).isEqualTo(HOST_NAME);
         assertThat(mPreference.mRadioGroup.getCheckedRadioButtonId()).isEqualTo(
-                R.id.private_dns_mode_opportunistic);
+                R.id.private_dns_mode_off);
     }
 
     @Test

tests/robotests/src/com/android/settings/network/PrivateDnsPreferenceControllerTest.java

@@ -0,0 +1,143 @@
+/*
+ * 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.network;
+
+import static android.arch.lifecycle.Lifecycle.Event.ON_START;
+import static android.arch.lifecycle.Lifecycle.Event.ON_STOP;
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OFF;
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
+import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_PROVIDER_HOSTNAME;
+import static android.provider.Settings.Global.PRIVATE_DNS_MODE;
+import static android.provider.Settings.Global.PRIVATE_DNS_SPECIFIER;
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.arch.lifecycle.LifecycleOwner;
+import android.content.Context;
+import android.content.ContentResolver;
+import android.database.ContentObserver;
+import android.provider.Settings;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+
+import com.android.settings.R;
+import com.android.settings.testutils.SettingsRobolectricTestRunner;
+import com.android.settingslib.core.lifecycle.Lifecycle;
+
+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.shadow.api.Shadow;
+import org.robolectric.shadows.ShadowContentResolver;
+
+
+@RunWith(SettingsRobolectricTestRunner.class)
+public class PrivateDnsPreferenceControllerTest {
+
+    private final static String HOSTNAME = "dns.example.com";
+
+    @Mock
+    private PreferenceScreen mScreen;
+    @Mock
+    private Preference mPreference;
+    private PrivateDnsPreferenceController mController;
+    private Context mContext;
+    private ContentResolver mContentResolver;
+    private ShadowContentResolver mShadowContentResolver;
+    private Lifecycle mLifecycle;
+    private LifecycleOwner mLifecycleOwner;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        mContext = spy(RuntimeEnvironment.application);
+        mContentResolver = mContext.getContentResolver();
+        mShadowContentResolver = Shadow.extract(mContentResolver);
+
+        when(mScreen.findPreference(anyString())).thenReturn(mPreference);
+
+        mController = spy(new PrivateDnsPreferenceController(mContext));
+        mLifecycleOwner = () -> mLifecycle;
+        mLifecycle = new Lifecycle(mLifecycleOwner);
+        mLifecycle.addObserver(mController);
+    }
+
+    @Test
+    public void goThroughLifecycle_shouldRegisterUnregisterSettingsObserver() {
+        mLifecycle.handleLifecycleEvent(ON_START);
+        verify(mContext, atLeastOnce()).getContentResolver();
+        assertThat(mShadowContentResolver.getContentObservers(
+                Settings.Global.getUriFor(PRIVATE_DNS_MODE))).isNotEmpty();
+        assertThat(mShadowContentResolver.getContentObservers(
+                Settings.Global.getUriFor(PRIVATE_DNS_SPECIFIER))).isNotEmpty();
+
+
+        mLifecycle.handleLifecycleEvent(ON_STOP);
+        verify(mContext, atLeastOnce()).getContentResolver();
+        assertThat(mShadowContentResolver.getContentObservers(
+                Settings.Global.getUriFor(PRIVATE_DNS_MODE))).isEmpty();
+        assertThat(mShadowContentResolver.getContentObservers(
+                Settings.Global.getUriFor(PRIVATE_DNS_SPECIFIER))).isEmpty();
+    }
+
+    @Test
+    public void getSummary_PrivateDnsModeOff() {
+        setPrivateDnsMode(PRIVATE_DNS_MODE_OFF);
+        setPrivateDnsProviderHostname(HOSTNAME);
+        mController.updateState(mPreference);
+        verify(mController, atLeastOnce()).getSummary();
+        verify(mPreference).setSummary(getResourceString(R.string.private_dns_mode_off));
+    }
+
+    @Test
+    public void getSummary_PrivateDnsModeOpportunistic() {
+        setPrivateDnsMode(PRIVATE_DNS_MODE_OPPORTUNISTIC);
+        setPrivateDnsProviderHostname(HOSTNAME);
+        mController.updateState(mPreference);
+        verify(mController, atLeastOnce()).getSummary();
+        verify(mPreference).setSummary(getResourceString(R.string.private_dns_mode_opportunistic));
+    }
+
+    @Test
+    public void getSummary_PrivateDnsModeProviderHostname() {
+        setPrivateDnsMode(PRIVATE_DNS_MODE_PROVIDER_HOSTNAME);
+        setPrivateDnsProviderHostname(HOSTNAME);
+        mController.updateState(mPreference);
+        verify(mController, atLeastOnce()).getSummary();
+        verify(mPreference).setSummary(HOSTNAME);
+    }
+
+    private void setPrivateDnsMode(String mode) {
+        Settings.Global.putString(mContentResolver, PRIVATE_DNS_MODE, mode);
+    }
+
+    private void setPrivateDnsProviderHostname(String name) {
+        Settings.Global.putString(mContentResolver, PRIVATE_DNS_SPECIFIER, name);
+    }
+
+    private String getResourceString(int which) {
+        return mContext.getResources().getString(which);
+    }
+}