Merge pull request #11249 from dextero/get-sms-zero

Make AT_CellularSMS::list_messages support index 0 in SMS inbox

Author: 0xc0170

UNITTESTS/features/cellular/framework/AT/at_cellularsms/at_cellularsmstest.cpp

@@ -137,7 +137,7 @@ TEST_F(TestAT_CellularSMS, test_AT_CellularSMS_get_sms)
     EXPECT_TRUE(NSAPI_ERROR_PARAMETER == sms.get_sms(NULL, 16, phone, 21, stamp, 21, &size));
 
     ATHandler_stub::resp_info_true_counter = 1;
-    ATHandler_stub::int_value = 0;
+    ATHandler_stub::int_value = -1;
     EXPECT_TRUE(-1 == sms.get_sms(buf, 16, phone, 21, stamp, 21, &size));
 
     //In below we are expecting the stub ATHandler info_resp() to respond

features/cellular/framework/AT/AT_CellularSMS.cpp

@@ -1044,7 +1044,7 @@ nsapi_error_t AT_CellularSMS::list_messages()
             (void)_at.consume_to_stop_tag(); // consume until <CR><LF>
         }
 
-        if (index > 0) {
+        if (index >= 0) {
             add_info(info, index, part_number);
         } else {
             delete info;