Fix/prefer is empty lint (#510)

* make sure the session terminates

* fix prefer_is_empty lint rule warnings

---------

Co-authored-by: Victor Uvarov <victoruvarov23@gmail.com>

Author: victortive

analysis_options.yaml

@@ -45,7 +45,6 @@ analyzer:
     library_prefixes: ignore
     unused_field: ignore
     avoid_init_to_null: ignore
-    prefer_is_empty: ignore
     unused_element: ignore
     curly_braces_in_flow_control_structures: ignore
     unnecessary_null_in_if_null_operators: ignore

lib/src/config.dart

@@ -85,7 +85,7 @@ class Checks {
        *  List of Objects and Socket: [{socket: socket1}, socket2]
        */
       List<SIPUASocketInterface> copy = <SIPUASocketInterface>[];
-      if (sockets is List && sockets!.length > 0) {
+      if (sockets is List && sockets!.isNotEmpty) {
         for (SIPUASocketInterface socket in sockets) {
           copy.add(socket);
         }

lib/src/name_addr_header.dart

@@ -89,7 +89,7 @@ class NameAddrHeader {
 
   @override
   String toString() {
-    String body = (_display_name != null && _display_name!.length > 0)
+    String body = (_display_name != null && _display_name!.isNotEmpty)
         ? '"${_quote(_display_name!)}" '
         : '';
 

lib/src/rtc_session/dtmf.dart

@@ -120,7 +120,7 @@ class DTMF extends EventManager {
     if (request.body != null) {
       List<String> body = request.body!.split('\n');
 
-      if (body.length >= 1) {
+      if (body.isNotEmpty) {
         if (body[0].contains(RegExp(reg_tone))) {
           _tone = body[0].replaceAll(reg_tone, '\$2');
         }

lib/src/socket_transport.dart

@@ -46,7 +46,7 @@ class SocketTransport {
     _recovery_options = recovery_options;
 
     // We must recieve at least 1 socket
-    if (sockets!.length == 0) {
+    if (sockets!.isEmpty) {
       throw Exceptions.TypeError(
           'invalid argument: Must recieve atleast 1 web socket');
     }

lib/src/transports/tcp_socket.dart

@@ -166,7 +166,7 @@ class SIPUATcpSocket extends SIPUASocketInterface {
   void _onMessage(dynamic data) {
     logger.d('Received TcpSocket data');
     if (data != null) {
-      if (data.toString().trim().length > 0) {
+      if (data.toString().trim().isNotEmpty) {
         ondata!(data);
       } else {
         logger.d('Received and ignored empty packet');

lib/src/transports/web_socket.dart

@@ -175,7 +175,7 @@ class SIPUAWebSocket extends SIPUASocketInterface {
   void _onMessage(dynamic data) {
     logger.d('Received WebSocket message');
     if (data != null) {
-      if (data.toString().trim().length > 0) {
+      if (data.toString().trim().isNotEmpty) {
         ondata!(data);
       } else {
         logger.d('Received and ignored empty packet');

lib/src/uri.dart

@@ -181,7 +181,7 @@ class URI {
       });
     });
 
-    if (headers.length > 0) {
+    if (headers.isNotEmpty) {
       uri += '?${headers.join('&')}';
     }