[CTS] Add test for getSubscriptionId in WifiInfo

Bug: 172867224
Test: atest WifiInfoTest
Change-Id: Idcd934732f4cf5278ca4709a9f5afcfc52e1e396
diff --git a/tests/tests/wifi/src/android/net/wifi/cts/WifiInfoTest.java b/tests/tests/wifi/src/android/net/wifi/cts/WifiInfoTest.java
index 537f199..45f8132 100644
--- a/tests/tests/wifi/src/android/net/wifi/cts/WifiInfoTest.java
+++ b/tests/tests/wifi/src/android/net/wifi/cts/WifiInfoTest.java
@@ -28,7 +28,7 @@
 import android.net.wifi.WifiManager;
 import android.net.wifi.WifiManager.WifiLock;
 import android.platform.test.annotations.AppModeFull;
-import android.test.AndroidTestCase;
+import android.telephony.SubscriptionManager;
 
 import androidx.core.os.BuildCompat;
 
@@ -37,7 +37,6 @@
 import com.android.compatibility.common.util.SystemUtil;
 
 import java.nio.charset.StandardCharsets;
-import java.util.concurrent.Callable;
 
 @AppModeFull(reason = "Cannot get WifiManager in instant app mode")
 public class WifiInfoTest extends WifiJUnit3TestBase {
@@ -230,6 +229,8 @@
         assertThat(info1.getRssi()).isEqualTo(TEST_RSSI);
         assertThat(info1.getNetworkId()).isEqualTo(TEST_NETWORK_ID);
         if (BuildCompat.isAtLeastS()) {
+            assertThat(info1.getSubscriptionId())
+                    .isEqualTo(SubscriptionManager.INVALID_SUBSCRIPTION_ID);
             assertFalse(info1.isOemPaid());
             assertFalse(info1.isOemPrivate());
             assertFalse(info1.isCarrierMerged());