Add CTS test for getSubscriptionId

Bug: 151094329
Test: atest SmsCbMessageTest
Change-Id: Ib702960e744158a76db4372520195ef7ef76dd63
diff --git a/tests/tests/telephony/current/src/android/telephony/cts/SmsCbMessageTest.java b/tests/tests/telephony/current/src/android/telephony/cts/SmsCbMessageTest.java
index 6b2ddbb..b157ab0 100644
--- a/tests/tests/telephony/current/src/android/telephony/cts/SmsCbMessageTest.java
+++ b/tests/tests/telephony/current/src/android/telephony/cts/SmsCbMessageTest.java
@@ -85,6 +85,12 @@
     }
 
     @Test
+    public void testSubId() {
+        assertEquals(TEST_SUB_ID, mSmsCbMessage.getSubscriptionId());
+    }
+
+
+    @Test
     public void testGeographicalScope() {
         assertEquals(TEST_GEO_SCOPE, mSmsCbMessage.getGeographicalScope());
     }