Start listening to telephony changes in #start()

Starting to listen on the handler races with the rest of
the constructor. The class already has a #start() method
meant to start listening, so implement better practices
by leveraging this method.

Test: CtsNetTestCases
      FrameworksNetIntegrationTests
      FrameworksNetTests
Change-Id: I772f761d3ca5f9711b9d988e6330b0878814f491

framework/src/android/net/util/MultinetworkPolicyTracker.java

@@ -109,8 +109,6 @@ public class MultinetworkPolicyTracker {
         this(ctx, handler, null);
     }
 
-    // TODO: Set the mini sdk to 31 and remove @TargetApi annotation when b/205923322 is addressed.
-    @TargetApi(Build.VERSION_CODES.S)
     public MultinetworkPolicyTracker(Context ctx, Handler handler, Runnable avoidBadWifiCallback) {
         mContext = ctx;
         mResources = new ConnectivityResources(ctx);
@@ -128,13 +126,12 @@ public class MultinetworkPolicyTracker {
             }
         };
 
-        ctx.getSystemService(TelephonyManager.class).registerTelephonyCallback(
-                new HandlerExecutor(handler), new ActiveDataSubscriptionIdListener());
-
         updateAvoidBadWifi();
         updateMeteredMultipathPreference();
     }
 
+    // TODO: Set the mini sdk to 31 and remove @TargetApi annotation when b/205923322 is addressed.
+    @TargetApi(Build.VERSION_CODES.S)
     public void start() {
         for (Uri uri : mSettingsUris) {
             mResolver.registerContentObserver(uri, false, mSettingObserver);
@@ -145,6 +142,9 @@ public class MultinetworkPolicyTracker {
         mContext.registerReceiverForAllUsers(mBroadcastReceiver, intentFilter,
                 null /* broadcastPermission */, mHandler);
 
+        mContext.getSystemService(TelephonyManager.class).registerTelephonyCallback(
+                new HandlerExecutor(mHandler), new ActiveDataSubscriptionIdListener());
+
         reevaluate();
     }
 

tests/unit/java/android/net/util/MultinetworkPolicyTrackerTest.kt

@@ -26,6 +26,7 @@ import android.net.ConnectivitySettingsManager.NETWORK_AVOID_BAD_WIFI
 import android.net.ConnectivitySettingsManager.NETWORK_METERED_MULTIPATH_PREFERENCE
 import android.net.util.MultinetworkPolicyTracker.ActiveDataSubscriptionIdListener
 import android.os.Build
+import android.os.Handler
 import android.provider.Settings
 import android.telephony.SubscriptionInfo
 import android.telephony.SubscriptionManager
@@ -40,6 +41,7 @@ import org.junit.After
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertTrue
+import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.ArgumentCaptor
@@ -48,6 +50,7 @@ import org.mockito.ArgumentMatchers.argThat
 import org.mockito.ArgumentMatchers.eq
 import org.mockito.Mockito.any
 import org.mockito.Mockito.doCallRealMethod
+import org.mockito.Mockito.doNothing
 import org.mockito.Mockito.doReturn
 import org.mockito.Mockito.mock
 import org.mockito.Mockito.times
@@ -90,7 +93,8 @@ class MultinetworkPolicyTrackerTest {
         Settings.Global.putString(resolver, NETWORK_AVOID_BAD_WIFI, "1")
         ConnectivityResources.setResourcesContextForTest(it)
     }
-    private val tracker = MultinetworkPolicyTracker(context, null /* handler */)
+    private val handler = mock(Handler::class.java)
+    private val tracker = MultinetworkPolicyTracker(context, handler)
 
     private fun assertMultipathPreference(preference: Int) {
         Settings.Global.putString(resolver, NETWORK_METERED_MULTIPATH_PREFERENCE,
@@ -99,6 +103,11 @@ class MultinetworkPolicyTrackerTest {
         assertEquals(preference, tracker.meteredMultipathPreference)
     }
 
+    @Before
+    fun setUp() {
+        tracker.start()
+    }
+
     @After
     fun tearDown() {
         ConnectivityResources.setResourcesContextForTest(null)