Fix SntpClientTest failures with no active network

The last change is using getActiveNetwork to run the queries, which
results in an NPE if there is no network on the device. Using network 0
causes no socket tagging and allows queries to the local test SNTP
server to go through as previously.

Also migrating to JUnit4 and moving mServer and mClient initializers to
setUp().

Test: SntpClientTest now passes
Change-Id: Ieb0a5d247129bcad89c1add0e9c1c504f516e2a9

core/tests/coretests/src/android/net/SntpClientTest.java

@@ -16,11 +16,19 @@
 
 package android.net;
 
-import android.content.Context;
-import android.test.AndroidTestCase;
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.Assert.assertTrue;
+
+import android.support.test.runner.AndroidJUnit4;
 import android.util.Log;
+
 import libcore.util.HexEncoding;
 
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
 import java.io.IOException;
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
@@ -28,8 +36,8 @@ import java.net.InetAddress;
 import java.net.SocketException;
 import java.util.Arrays;
 
-
-public class SntpClientTest extends AndroidTestCase {
+@RunWith(AndroidJUnit4.class)
+public class SntpClientTest {
     private static final String TAG = "SntpClientTest";
 
     private static final int ORIGINATE_TIME_OFFSET = 24;
@@ -58,18 +66,19 @@ public class SntpClientTest extends AndroidTestCase {
             "d9ca945194bd3fff" +
             "d9ca945194bd4001";
 
-    private final SntpTestServer mServer = new SntpTestServer();
-    private final SntpClient mClient = new SntpClient();
-
+    private SntpTestServer mServer;
+    private SntpClient mClient;
     private Network mNetwork;
 
-    @Override
-    protected void setUp() throws Exception {
-        super.setUp();
-        ConnectivityManager mCM = getContext().getSystemService(ConnectivityManager.class);
-        mNetwork = mCM.getActiveNetwork();
+    @Before
+    public void setUp() throws Exception {
+        // NETID_UNSET allows the test to run, with a loopback server, even w/o external networking
+        mNetwork = new Network(ConnectivityManager.NETID_UNSET);
+        mServer = new SntpTestServer();
+        mClient = new SntpClient();
     }
 
+    @Test
     public void testBasicWorkingSntpClientQuery() throws Exception {
         mServer.setServerReply(HexEncoding.decode(WORKING_VERSION4.toCharArray(), false));
         assertTrue(mClient.requestTime(mServer.getAddress(), mServer.getPort(), 500, mNetwork));
@@ -77,10 +86,12 @@ public class SntpClientTest extends AndroidTestCase {
         assertEquals(1, mServer.numRepliesSent());
     }
 
+    @Test
     public void testDnsResolutionFailure() throws Exception {
         assertFalse(mClient.requestTime("ntp.server.doesnotexist.example", 5000, mNetwork));
     }
 
+    @Test
     public void testTimeoutFailure() throws Exception {
         mServer.clearServerReply();
         assertFalse(mClient.requestTime(mServer.getAddress(), mServer.getPort(), 500, mNetwork));
@@ -88,6 +99,7 @@ public class SntpClientTest extends AndroidTestCase {
         assertEquals(0, mServer.numRepliesSent());
     }
 
+    @Test
     public void testIgnoreLeapNoSync() throws Exception {
         final byte[] reply = HexEncoding.decode(WORKING_VERSION4.toCharArray(), false);
         reply[0] |= (byte) 0xc0;
@@ -97,6 +109,7 @@ public class SntpClientTest extends AndroidTestCase {
         assertEquals(1, mServer.numRepliesSent());
     }
 
+    @Test
     public void testAcceptOnlyServerAndBroadcastModes() throws Exception {
         final byte[] reply = HexEncoding.decode(WORKING_VERSION4.toCharArray(), false);
         for (int i = 0; i <= 7; i++) {
@@ -120,6 +133,7 @@ public class SntpClientTest extends AndroidTestCase {
         }
     }
 
+    @Test
     public void testAcceptableStrataOnly() throws Exception {
         final int STRATUM_MIN = 1;
         final int STRATUM_MAX = 15;
@@ -141,6 +155,7 @@ public class SntpClientTest extends AndroidTestCase {
         }
     }
 
+    @Test
     public void testZeroTransmitTime() throws Exception {
         final byte[] reply = HexEncoding.decode(WORKING_VERSION4.toCharArray(), false);
         Arrays.fill(reply, TRANSMIT_TIME_OFFSET, TRANSMIT_TIME_OFFSET + 8, (byte) 0x00);