Move getTestableNetworks method to CtsNetUtils

This is a no-op change to move the getTestableNetworks() to
CtsNetUtils for the follow up change which will also need the
same method to reduce code duplication.

This change also updates the nullability of the private dns
server so that it can also verify non-strict mode.

Test: atest CtsNetTestCases
Change-Id: I67c94cd5aefeb9cf1ecd4126178c2410f3f08b1b
diff --git a/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java b/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java
index 691ab99..17a9ca2 100644
--- a/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java
+++ b/tests/cts/net/src/android/net/cts/MultinetworkApiTest.java
@@ -18,21 +18,18 @@
 
 import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
 
-import android.content.Context;
 import android.content.ContentResolver;
+import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.Network;
 import android.net.NetworkCapabilities;
 import android.net.NetworkUtils;
 import android.net.cts.util.CtsNetUtils;
 import android.platform.test.annotations.AppModeFull;
-import android.provider.Settings;
 import android.system.ErrnoException;
 import android.system.OsConstants;
 import android.test.AndroidTestCase;
 
-import java.util.ArrayList;
-
 public class MultinetworkApiTest extends AndroidTestCase {
 
     static {
@@ -75,26 +72,8 @@
         super.tearDown();
     }
 
-    private Network[] getTestableNetworks() {
-        final ArrayList<Network> testableNetworks = new ArrayList<Network>();
-        for (Network network : mCM.getAllNetworks()) {
-            final NetworkCapabilities nc = mCM.getNetworkCapabilities(network);
-            if (nc != null
-                    && nc.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED)
-                    && nc.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)) {
-                testableNetworks.add(network);
-            }
-        }
-
-        assertTrue(
-                "This test requires that at least one network be connected. " +
-                "Please ensure that the device is connected to a network.",
-                testableNetworks.size() >= 1);
-        return testableNetworks.toArray(new Network[0]);
-    }
-
     public void testGetaddrinfo() throws ErrnoException {
-        for (Network network : getTestableNetworks()) {
+        for (Network network : mCtsNetUtils.getTestableNetworks()) {
             int errno = runGetaddrinfoCheck(network.getNetworkHandle());
             if (errno != 0) {
                 throw new ErrnoException(
@@ -109,7 +88,7 @@
         assertNull(mCM.getProcessDefaultNetwork());
         assertEquals(0, NetworkUtils.getBoundNetworkForProcess());
 
-        for (Network network : getTestableNetworks()) {
+        for (Network network : mCtsNetUtils.getTestableNetworks()) {
             mCM.setProcessDefaultNetwork(null);
             assertNull(mCM.getProcessDefaultNetwork());
 
@@ -128,7 +107,7 @@
             mCM.setProcessDefaultNetwork(null);
         }
 
-        for (Network network : getTestableNetworks()) {
+        for (Network network : mCtsNetUtils.getTestableNetworks()) {
             NetworkUtils.bindProcessToNetwork(0);
             assertNull(mCM.getBoundNetworkForProcess());
 
@@ -148,7 +127,7 @@
 
     @AppModeFull(reason = "CHANGE_NETWORK_STATE permission can't be granted to instant apps")
     public void testSetsocknetwork() throws ErrnoException {
-        for (Network network : getTestableNetworks()) {
+        for (Network network : mCtsNetUtils.getTestableNetworks()) {
             int errno = runSetsocknetwork(network.getNetworkHandle());
             if (errno != 0) {
                 throw new ErrnoException(
@@ -158,7 +137,7 @@
     }
 
     public void testNativeDatagramTransmission() throws ErrnoException {
-        for (Network network : getTestableNetworks()) {
+        for (Network network : mCtsNetUtils.getTestableNetworks()) {
             int errno = runDatagramCheck(network.getNetworkHandle());
             if (errno != 0) {
                 throw new ErrnoException(
@@ -181,7 +160,7 @@
 
     public void testNetworkHandle() {
         // Test Network -> NetworkHandle -> Network results in the same Network.
-        for (Network network : getTestableNetworks()) {
+        for (Network network : mCtsNetUtils.getTestableNetworks()) {
             long networkHandle = network.getNetworkHandle();
             Network newNetwork = Network.fromNetworkHandle(networkHandle);
             assertEquals(newNetwork, network);
@@ -203,7 +182,7 @@
     }
 
     public void testResNApi() throws Exception {
-        final Network[] testNetworks = getTestableNetworks();
+        final Network[] testNetworks = mCtsNetUtils.getTestableNetworks();
 
         for (Network network : testNetworks) {
             // Throws AssertionError directly in jni function if test fail.
@@ -229,7 +208,7 @@
         // b/144521720
         try {
             mCtsNetUtils.setPrivateDnsStrictMode(GOOGLE_PRIVATE_DNS_SERVER);
-            for (Network network : getTestableNetworks()) {
+            for (Network network : mCtsNetUtils.getTestableNetworks()) {
               // Wait for private DNS setting to propagate.
               mCtsNetUtils.awaitPrivateDnsSetting("NxDomain test wait private DNS setting timeout",
                         network, GOOGLE_PRIVATE_DNS_SERVER, true);
diff --git a/tests/cts/net/util/java/android/net/cts/util/CtsNetUtils.java b/tests/cts/net/util/java/android/net/cts/util/CtsNetUtils.java
index d817630..0c4f794 100644
--- a/tests/cts/net/util/java/android/net/cts/util/CtsNetUtils.java
+++ b/tests/cts/net/util/java/android/net/cts/util/CtsNetUtils.java
@@ -57,6 +57,8 @@
 import android.text.TextUtils;
 import android.util.Log;
 
+import androidx.annotation.Nullable;
+
 import com.android.compatibility.common.util.PollingCheck;
 import com.android.compatibility.common.util.ShellIdentityUtils;
 import com.android.compatibility.common.util.SystemUtil;
@@ -68,6 +70,8 @@
 import java.io.OutputStream;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.util.ArrayList;
+import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -506,17 +510,18 @@
      * @throws InterruptedException If the thread is interrupted.
      */
     public void awaitPrivateDnsSetting(@NonNull String msg, @NonNull Network network,
-            @NonNull String server, boolean requiresValidatedServer) throws InterruptedException {
+            @Nullable String server, boolean requiresValidatedServer) throws InterruptedException {
         final CountDownLatch latch = new CountDownLatch(1);
         final NetworkRequest request = new NetworkRequest.Builder().clearCapabilities().build();
-        NetworkCallback callback = new NetworkCallback() {
+        final NetworkCallback callback = new NetworkCallback() {
             @Override
             public void onLinkPropertiesChanged(Network n, LinkProperties lp) {
                 Log.i(TAG, "Link properties of network " + n + " changed to " + lp);
                 if (requiresValidatedServer && lp.getValidatedPrivateDnsServers().isEmpty()) {
                     return;
                 }
-                if (network.equals(n) && server.equals(lp.getPrivateDnsServerName())) {
+                Log.i(TAG, "Set private DNS server to " + server);
+                if (network.equals(n) && Objects.equals(server, lp.getPrivateDnsServerName())) {
                     latch.countDown();
                 }
             }
@@ -539,6 +544,27 @@
     }
 
     /**
+     * Get all testable Networks with internet capability.
+     */
+    public Network[] getTestableNetworks() {
+        final ArrayList<Network> testableNetworks = new ArrayList<Network>();
+        for (Network network : mCm.getAllNetworks()) {
+            final NetworkCapabilities nc = mCm.getNetworkCapabilities(network);
+            if (nc != null
+                    && nc.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED)
+                    && nc.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)) {
+                testableNetworks.add(network);
+            }
+        }
+
+        assertTrue("This test requires that at least one public Internet-providing"
+                        + " network be connected. Please ensure that the device is connected to"
+                        + " a network.",
+                testableNetworks.size() >= 1);
+        return testableNetworks.toArray(new Network[0]);
+    }
+
+    /**
      * Receiver that captures the last connectivity change's network type and state. Recognizes
      * both {@code CONNECTIVITY_ACTION} and {@code NETWORK_CALLBACK_ACTION} intents.
      */