prepare to use Signal in verification SMS text

Closes #5352
// FREEBIE

src/org/thoughtcrime/securesms/service/SmsListener.java

@@ -41,7 +41,7 @@ public class SmsListener extends BroadcastReceiver {
   private static final String SMS_RECEIVED_ACTION  = Telephony.Sms.Intents.SMS_RECEIVED_ACTION;
   private static final String SMS_DELIVERED_ACTION = Telephony.Sms.Intents.SMS_DELIVER_ACTION;
 
-  private static final Pattern CHALLENGE_PATTERN = Pattern.compile(".*Your TextSecure verification code: ([0-9]{3,4})-([0-9]{3,4}).*", Pattern.DOTALL);
+  private static final Pattern CHALLENGE_PATTERN = Pattern.compile(".*Your (Signal|TextSecure) verification code: ([0-9]{3,4})-([0-9]{3,4}).*", Pattern.DOTALL);
 
   private boolean isExemption(SmsMessage message, String messageBody) {
 
@@ -136,7 +136,7 @@ public class SmsListener extends BroadcastReceiver {
       throw new AssertionError("Expression should match.");
     }
 
-    return challengeMatcher.group(1) + challengeMatcher.group(2);
+    return challengeMatcher.group(2) + challengeMatcher.group(3);
   }
 
   @Override

test/unitTest/java/org/thoughtcrime/securesms/service/SmsListenerTest.java

@@ -24,6 +24,14 @@ public class SmsListenerTest extends BaseUnitTest {
       put("Your TextSecure verification code: 1337-1337",      "13371337");
       put("XXXYour TextSecure verification code: 1337-1337",   "13371337");
       put("Your TextSecure verification code: 1337-1337XXX",   "13371337");
+
+      put("Your Signal verification code: 337-337",        "337337");
+      put("XXX\nYour Signal verification code: 1337-1337", "13371337");
+      put("Your Signal verification code: 337-1337",       "3371337");
+      put("Your Signal verification code: 1337-337",       "1337337");
+      put("Your Signal verification code: 1337-1337",      "13371337");
+      put("XXXYour Signal verification code: 1337-1337",   "13371337");
+      put("Your Signal verification code: 1337-1337XXX",   "13371337");
   }};
 
   private SmsListener listener;