refactor: Replace MayFail by Result

We can now return what exactly made a connection attempt fail.

packages/moxxmpp/integration_test/failure_reconnection_test.dart

@@ -10,7 +10,7 @@ void main() {
   });
   final log = Logger('FailureReconnectionTest');
 
-  test('Failing an awaited connection', () async {
+  test('Failing an awaited connection with TestingSleepReconnectionPolicy', () async {
     var errors = 0;
     final connection = XmppConnection(
       TestingSleepReconnectionPolicy(10),
@@ -52,4 +52,47 @@ void main() {
     await Future.delayed(const Duration(seconds: 20));
     expect(errors, 1);
   }, timeout: Timeout.factor(2));
+
+  test('Failing an awaited connection with ExponentialBackoffReconnectionPolicy', () async {
+    var errors = 0;
+    final connection = XmppConnection(
+      ExponentialBackoffReconnectionPolicy(1),
+      TCPSocketWrapper(false),
+    );
+    connection.registerFeatureNegotiators([
+      StartTlsNegotiator(),
+    ]);
+    connection.registerManagers([
+      DiscoManager(),
+      RosterManager(),
+      PingManager(),
+      MessageManager(),
+      PresenceManager('http://moxxmpp.example'),
+    ]);
+    connection.asBroadcastStream().listen((event) {
+      if (event is ConnectionStateChangedEvent) {
+        if (event.state == XmppConnectionState.error) {
+          errors++;
+        }
+      }
+    });
+
+    connection.setConnectionSettings(
+      ConnectionSettings(
+        jid: JID.fromString('testuser@no-sasl.badxmpp.eu'),
+        password: 'abc123',
+        useDirectTLS: true,
+        allowPlainAuth: true,
+      ),
+    );
+
+    final result = await connection.connectAwaitable();
+    log.info('Connection failed as expected');
+    expect(result.success, false);
+    expect(errors, 1);
+
+    log.info('Waiting 20 seconds for unexpected reconnections');
+    await Future.delayed(const Duration(seconds: 20));
+    expect(errors, 1);
+  }, timeout: Timeout.factor(2));
 }

packages/moxxmpp/lib/moxxmpp.dart

@@ -25,12 +25,12 @@ export 'package:moxxmpp/src/presence.dart';
 export 'package:moxxmpp/src/reconnect.dart';
 export 'package:moxxmpp/src/rfcs/rfc_2782.dart';
 export 'package:moxxmpp/src/rfcs/rfc_4790.dart';
-export 'package:moxxmpp/src/roster.dart';
+export 'package:moxxmpp/src/roster/errors.dart';
+export 'package:moxxmpp/src/roster/roster.dart';
 export 'package:moxxmpp/src/settings.dart';
 export 'package:moxxmpp/src/socket.dart';
 export 'package:moxxmpp/src/stanza.dart';
 export 'package:moxxmpp/src/stringxml.dart';
-export 'package:moxxmpp/src/types/error.dart';
 export 'package:moxxmpp/src/types/result.dart';
 export 'package:moxxmpp/src/xeps/staging/extensible_file_thumbnails.dart';
 export 'package:moxxmpp/src/xeps/staging/file_upload_notification.dart';
@@ -61,7 +61,8 @@ export 'package:moxxmpp/src/xeps/xep_0333.dart';
 export 'package:moxxmpp/src/xeps/xep_0334.dart';
 export 'package:moxxmpp/src/xeps/xep_0352.dart';
 export 'package:moxxmpp/src/xeps/xep_0359.dart';
-export 'package:moxxmpp/src/xeps/xep_0363.dart';
+export 'package:moxxmpp/src/xeps/xep_0363/errors.dart';
+export 'package:moxxmpp/src/xeps/xep_0363/xep_0363.dart';
 export 'package:moxxmpp/src/xeps/xep_0380.dart';
 export 'package:moxxmpp/src/xeps/xep_0384/crypto.dart';
 export 'package:moxxmpp/src/xeps/xep_0384/errors.dart';

packages/moxxmpp/lib/src/connection.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'package:logging/logging.dart';
 import 'package:meta/meta.dart';
 import 'package:moxxmpp/src/buffer.dart';
+import 'package:moxxmpp/src/errors.dart';
 import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/iq.dart';
 import 'package:moxxmpp/src/managers/attributes.dart';
@@ -14,7 +15,7 @@ import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/presence.dart';
 import 'package:moxxmpp/src/reconnect.dart';
-import 'package:moxxmpp/src/roster.dart';
+import 'package:moxxmpp/src/roster/roster.dart';
 import 'package:moxxmpp/src/routing.dart';
 import 'package:moxxmpp/src/settings.dart';
 import 'package:moxxmpp/src/socket.dart';
@@ -61,14 +62,14 @@ class XmppConnectionResult {
   const XmppConnectionResult(
     this.success,
     {
-      this.reason,
+      this.error,
     }
   );
 
   final bool success;
-  // NOTE: [reason] is not human-readable, but the type of SASL error.
-  //       See sasl/errors.dart
-  final String? reason;
+  // If a connection attempt fails, i.e. success is false, then this indicates the
+  // reason the connection failed.
+  final XmppError? error;
 }
 
 class XmppConnection {
@@ -345,12 +346,8 @@ class XmppConnection {
   }
   
   /// Called when a stream ending error has occurred
-  Future<void> handleError(Object? error) async {
-    if (error != null) {
-      _log.severe('handleError: $error');
-    } else {
-      _log.severe('handleError: Called with null');
-    } 
+  Future<void> handleError(XmppError error) async {
+    _log.severe('handleError called with ${error.toString()}');
 
     // Whenever we encounter an error that would trigger a reconnection attempt while
     // the connection result is being awaited, don't attempt a reconnection but instead
@@ -358,7 +355,12 @@ class XmppConnection {
     if (_connectionCompleter != null) {
       _log.info('Not triggering reconnection since connection result is being awaited');
       await _disconnect(triggeredByUser: false, state: XmppConnectionState.error);
-      _connectionCompleter?.complete(const XmppConnectionResult(false));
+      _connectionCompleter?.complete(
+        XmppConnectionResult(
+          false,
+          error: error,
+        ),
+      );
       _connectionCompleter = null;
       return;
     }
@@ -370,7 +372,7 @@ class XmppConnection {
   /// Called whenever the socket creates an event
   Future<void> _handleSocketEvent(XmppSocketEvent event) async {
     if (event is XmppSocketErrorEvent) {
-      await handleError(event.error);
+      await handleError(SocketError(event));
     } else if (event is XmppSocketClosureEvent) {
       if (_socketClosureTriggersReconnect) {
         _log.fine('Received XmppSocketClosureEvent. Reconnecting...');
@@ -525,7 +527,7 @@ class XmppConnection {
   /// Called when we timeout during connecting
   Future<void> _onConnectingTimeout() async {
     _log.severe('Connection stuck in "connecting". Causing a reconnection...');
-    await handleError('Connecting timeout');
+    await handleError(TimeoutError());
   }
 
   void _destroyConnectingTimer() {
@@ -750,19 +752,33 @@ class XmppConnection {
     await getPresenceManager().sendInitialPresence();
   }
 
-  /// To be called after _currentNegotiator!.negotiate(..) has been called. Checks the
-  /// state of the negotiator and picks the next negotiatior, ends negotiation or
-  /// waits, depending on what the negotiator did.
-  Future<void> _checkCurrentNegotiator() async {
-    if (_currentNegotiator!.state == NegotiatorState.done) {
-      _log.finest('Negotiator ${_currentNegotiator!.id} done');
+  Future<void> _executeCurrentNegotiator(XMLNode nonza) async {
+    // If we don't have a negotiator get one
+    _currentNegotiator ??= getNextNegotiator(_streamFeatures);
+    if (_currentNegotiator == null && _isMandatoryNegotiationDone(_streamFeatures) && !_isNegotiationPossible(_streamFeatures)) {
+      _log.finest('Negotiations done!');
+      _updateRoutingState(RoutingState.handleStanzas);
+      await _onNegotiationsDone();
+      return;
+    }
 
+    final result = await _currentNegotiator!.negotiate(nonza);
+    if (result.isType<NegotiatorError>()) {
+      _log.severe('Negotiator returned an error');
+      await handleError(result.get<NegotiatorError>());
+      return;
+    }
+
+    final state = result.get<NegotiatorState>();
+    _currentNegotiator!.state = state;
+    switch (state) {
+      case NegotiatorState.ready: return;
+      case NegotiatorState.done:
       if (_currentNegotiator!.sendStreamHeaderWhenDone) {
         _currentNegotiator = null;
         _streamFeatures.clear();
         _sendStreamHeader();
       } else {
-        // Track what features we still have
         _streamFeatures
           .removeWhere((node) {
             return node.attributes['xmlns'] == _currentNegotiator!.negotiatingXmlns;
@@ -772,7 +788,6 @@ class XmppConnection {
         if (_isMandatoryNegotiationDone(_streamFeatures) && !_isNegotiationPossible(_streamFeatures)) {
           _log.finest('Negotiations done!');
           _updateRoutingState(RoutingState.handleStanzas);
-
           await _onNegotiationsDone();
         } else {
           _currentNegotiator = getNextNegotiator(_streamFeatures);
@@ -782,15 +797,16 @@ class XmppConnection {
             tag: 'stream:features',
             children: _streamFeatures,
           );
-          await _currentNegotiator!.negotiate(fakeStanza);
-          await _checkCurrentNegotiator();
+
+          await _executeCurrentNegotiator(fakeStanza);
         }
       }
-    } else if (_currentNegotiator!.state == NegotiatorState.retryLater) {
+      break;
+      case NegotiatorState.retryLater:
       _log.finest('Negotiator wants to continue later. Picking new one...');
-
       _currentNegotiator!.state = NegotiatorState.ready;
 
+      
       if (_isMandatoryNegotiationDone(_streamFeatures) && !_isNegotiationPossible(_streamFeatures)) {
         _log.finest('Negotiations done!');
 
@@ -804,24 +820,18 @@ class XmppConnection {
           tag: 'stream:features',
           children: _streamFeatures,
         );
-        await _currentNegotiator!.negotiate(fakeStanza);
-        await _checkCurrentNegotiator();
+        await _executeCurrentNegotiator(fakeStanza);
       }
-    } else if (_currentNegotiator!.state == NegotiatorState.skipRest) {
+      break;
+      case NegotiatorState.skipRest:
       _log.finest('Negotiator wants to skip the remaining negotiation... Negotiations (assumed) done!');
 
       _updateRoutingState(RoutingState.handleStanzas);
       await _onNegotiationsDone();
-    } else if (_currentNegotiator!.state == NegotiatorState.error) {
-      _log.severe('Negotiator returned an error');
-      await handleError(null);
+      break;
     }
   }
   
-  void _closeSocket() {
-    _socket.close();
-  }
-  
   /// Called whenever we receive data that has been parsed as XML.
   Future<void> handleXmlStream(XMLNode node) async {
     // Check if we received a stream error
@@ -829,7 +839,7 @@ class XmppConnection {
       _log
         ..finest('<== ${node.toXml()}')
         ..severe('Received a stream error! Attempting reconnection');
-      await handleError('Stream error');
+      await handleError(StreamError());
       
       return;
     }
@@ -849,53 +859,14 @@ class XmppConnection {
             return;
           }
 
-          if (_currentNegotiator != null) {
-            // If we already have a negotiator, just let it do its thing
-            _log.finest('Negotiator currently active...');
-
-            await _currentNegotiator!.negotiate(node);
-            await _checkCurrentNegotiator();
-          } else {
+          if (node.tag == 'stream:features') {
+            // Store the received stream features
             _streamFeatures
-            ..clear()
-            ..addAll(node.children);
-
-            // We need to pick a new one
-            if (_isMandatoryNegotiationDone(node.children)) {
-              // Mandatory features are done but can we still negotiate more?
-              if (_isNegotiationPossible(node.children)) {// We can still negotiate features, so do that.
-                _log.finest('All required stream features done! Continuing negotiation');
-                _currentNegotiator = getNextNegotiator(node.children);
-                _log.finest('Chose $_currentNegotiator as next negotiator');
-                await _currentNegotiator!.negotiate(node);
-                await _checkCurrentNegotiator();
-              } else {
-                _updateRoutingState(RoutingState.handleStanzas);
-              }
-            } else {
-              // There still are mandatory features
-              if (!_isNegotiationPossible(node.children)) {
-                _log.severe('Mandatory negotiations not done but continuation not possible');
-                _updateRoutingState(RoutingState.error);
-                await _setConnectionState(XmppConnectionState.error);
-
-                // Resolve the connection completion future
-                _connectionCompleter?.complete(
-                  const XmppConnectionResult(
-                    false,
-                    reason: 'Could not complete connection negotiations',
-                  ),
-                );
-                _connectionCompleter = null;
-                return;
-              }
-
-              _currentNegotiator = getNextNegotiator(node.children);
-              _log.finest('Chose $_currentNegotiator as next negotiator');
-              await _currentNegotiator!.negotiate(node);
-              await _checkCurrentNegotiator();
-            }
+              ..clear()
+              ..addAll(node.children);
           }
+
+          await _executeCurrentNegotiator(node);
         });
         break;
       case RoutingState.handleStanzas:        
@@ -927,20 +898,6 @@ class XmppConnection {
     } else if (event is AuthenticationSuccessEvent) {
       _log.finest('Received AuthenticationSuccessEvent. Setting _isAuthenticated to true');
       _isAuthenticated = true;
-    } else if (event is AuthenticationFailedEvent) {
-      _log.finest('Failed authentication');
-      _updateRoutingState(RoutingState.error);
-      await _setConnectionState(XmppConnectionState.error);
-
-      // Resolve the connection completion future
-      _connectionCompleter?.complete(
-        XmppConnectionResult(
-          false,
-          reason: 'Authentication failed: ${event.saslError}',
-        ),
-      );
-      _connectionCompleter = null;
-      _closeSocket();
     }
     
     for (final manager in _xmppManagers.values) {
@@ -1053,7 +1010,7 @@ class XmppConnection {
       port: port,
     );
     if (!result) {
-      await handleError(null);
+      await handleError(NoConnectionError());
     } else {
       await _reconnectionPolicy.onSuccess();
       _log.fine('Preparing the internal state for a connection attempt');

packages/moxxmpp/lib/src/errors.dart

@@ -0,0 +1,20 @@
+import 'package:moxxmpp/src/socket.dart';
+
+/// An internal error class
+abstract class XmppError {}
+
+/// Returned if we could not establish a TCP connection
+/// to the server.
+class NoConnectionError extends XmppError {}
+
+/// Returned if a socket error occured
+class SocketError extends XmppError {
+  SocketError(this.event);
+  final XmppSocketErrorEvent event;
+}
+
+/// Returned if we time out
+class TimeoutError extends XmppError {}
+
+/// Returned if we received a stream error
+class StreamError extends XmppError {}

packages/moxxmpp/lib/src/negotiators/negotiator.dart

@@ -1,10 +1,12 @@
 import 'package:moxlib/moxlib.dart';
+import 'package:moxxmpp/src/errors.dart';
 import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/jid.dart';
 import 'package:moxxmpp/src/managers/base.dart';
 import 'package:moxxmpp/src/settings.dart';
 import 'package:moxxmpp/src/socket.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 
 /// The state a negotiator is currently in
 enum NegotiatorState {
@@ -14,15 +16,15 @@ enum NegotiatorState {
   done,
   // Cancel the current attempt but we are not done
   retryLater,
-  // The negotiator is in an error state
-  error,
   // Skip the rest of the negotiation and assume the stream ready. Only use this when
   // using stream restoration XEPs, like Stream Management.
   skipRest,
 }
 
-class NegotiatorAttributes {
+/// A base class for all errors that may occur during feature negotiation
+abstract class NegotiatorError extends XmppError {}
 
+class NegotiatorAttributes {
   const NegotiatorAttributes(
     this.sendNonza,
     this.getConnectionSettings,
@@ -97,7 +99,7 @@ abstract class XmppFeatureNegotiatorBase {
   /// must switch some internal state to prevent getting matched immediately again.
   /// If ready is returned, then the negotiator indicates that it is not done with
   /// negotiation.
-  Future<void> negotiate(XMLNode nonza);
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza);
 
   /// Reset the negotiator to a state that negotation can happen again.
   void reset() {

packages/moxxmpp/lib/src/negotiators/resource_binding.dart

@@ -4,9 +4,12 @@ import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 import 'package:moxxmpp/src/xeps/xep_0198/xep_0198.dart';
 import 'package:uuid/uuid.dart';
 
+class ResourceBindingFailedError extends NegotiatorError {}
+
 class ResourceBindingNegotiator extends XmppFeatureNegotiatorBase {
 
   ResourceBindingNegotiator() : _requestSent = false, super(0, false, bindXmlns, resourceBindingNegotiator);
@@ -23,7 +26,7 @@ class ResourceBindingNegotiator extends XmppFeatureNegotiatorBase {
   }
   
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     if (!_requestSent) {
       final stanza = XMLNode.xmlns(
         tag: 'iq',
@@ -42,10 +45,10 @@ class ResourceBindingNegotiator extends XmppFeatureNegotiatorBase {
 
       _requestSent = true;
       attributes.sendNonza(stanza);
+      return const Result(NegotiatorState.ready);
     } else {
       if (nonza.tag != 'iq' || nonza.attributes['type'] != 'result') {
-        state = NegotiatorState.error;
-        return;
+        return Result(ResourceBindingFailedError());
       }
 
       final bind = nonza.firstTag('bind')!;
@@ -53,7 +56,7 @@ class ResourceBindingNegotiator extends XmppFeatureNegotiatorBase {
       final resource = jid.innerText().split('/')[1];
 
       await attributes.sendEvent(ResourceBindingSuccessEvent(resource: resource));
-      state = NegotiatorState.done;
+      return const Result(NegotiatorState.done);
     }
   }
   

packages/moxxmpp/lib/src/negotiators/sasl/errors.dart

@@ -0,0 +1,3 @@
+import 'package:moxxmpp/src/negotiators/negotiator.dart';
+
+class SaslFailedError extends NegotiatorError {}

packages/moxxmpp/lib/src/negotiators/sasl/plain.dart

@@ -1,12 +1,13 @@
 import 'dart:convert';
-
 import 'package:logging/logging.dart';
 import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
+import 'package:moxxmpp/src/negotiators/sasl/errors.dart';
 import 'package:moxxmpp/src/negotiators/sasl/negotiator.dart';
 import 'package:moxxmpp/src/negotiators/sasl/nonza.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 
 class SaslPlainAuthNonza extends SaslAuthNonza {
   SaslPlainAuthNonza(String username, String password) : super(
@@ -15,7 +16,6 @@ class SaslPlainAuthNonza extends SaslAuthNonza {
 }
 
 class SaslPlainNegotiator extends SaslNegotiator {
-  
   SaslPlainNegotiator()
     : _authSent = false,
       _log = Logger('SaslPlainNegotiator'),
@@ -41,7 +41,7 @@ class SaslPlainNegotiator extends SaslNegotiator {
   }
 
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     if (!_authSent) {
       final settings = attributes.getConnectionSettings();
       attributes.sendNonza(
@@ -49,17 +49,17 @@ class SaslPlainNegotiator extends SaslNegotiator {
         redact: SaslPlainAuthNonza('******', '******').toXml(),
       );
       _authSent = true;
+      return const Result(NegotiatorState.ready);
     } else {
       final tag = nonza.tag;
       if (tag == 'success') {
         await attributes.sendEvent(AuthenticationSuccessEvent());
-        state = NegotiatorState.done;
+        return const Result(NegotiatorState.done);
       } else {
         // We assume it's a <failure/>
         final error = nonza.children.first.tag;
         await attributes.sendEvent(AuthenticationFailedEvent(error));
-        
-        state = NegotiatorState.error;
+        return Result(SaslFailedError());
       }
     }
   }

packages/moxxmpp/lib/src/negotiators/sasl/scram.dart

@@ -1,16 +1,17 @@
 import 'dart:convert';
 import 'dart:math' show Random;
-
 import 'package:cryptography/cryptography.dart';
 import 'package:logging/logging.dart';
 import 'package:moxxmpp/src/events.dart';
 import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
+import 'package:moxxmpp/src/negotiators/sasl/errors.dart';
 import 'package:moxxmpp/src/negotiators/sasl/kv.dart';
 import 'package:moxxmpp/src/negotiators/sasl/negotiator.dart';
 import 'package:moxxmpp/src/negotiators/sasl/nonza.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 import 'package:random_string/random_string.dart';
 import 'package:saslprep/saslprep.dart';
 
@@ -89,7 +90,6 @@ enum ScramState {
 const gs2Header = 'n,,';
 
 class SaslScramNegotiator extends SaslNegotiator {
-  
   // NOTE: NEVER, and I mean, NEVER set clientNonce or initalMessageNoGS2. They are just there for testing
   SaslScramNegotiator(
     int priority,
@@ -197,7 +197,7 @@ class SaslScramNegotiator extends SaslNegotiator {
   }
   
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     switch (_scramState) {
       case ScramState.preSent:
         if (clientNonce == null || clientNonce == '') {
@@ -211,15 +211,14 @@ class SaslScramNegotiator extends SaslNegotiator {
           SaslScramAuthNonza(body: base64.encode(utf8.encode(gs2Header + initialMessageNoGS2)), type: hashType),
           redact: SaslScramAuthNonza(body: '******', type: hashType).toXml(),
         );
-        break;
+        return const Result(NegotiatorState.ready);
       case ScramState.initialMessageSent:
         if (nonza.tag != 'challenge') {
           final error = nonza.children.first.tag;
           await attributes.sendEvent(AuthenticationFailedEvent(error));
 
-          state = NegotiatorState.error;
           _scramState = ScramState.error;
-          return;
+          return Result(SaslFailedError());
         }
 
         final challengeBase64 = nonza.innerText();
@@ -230,15 +229,14 @@ class SaslScramNegotiator extends SaslNegotiator {
           SaslScramResponseNonza(body: responseBase64),
           redact: SaslScramResponseNonza(body: '******').toXml(),
         );
-        return;
+        return const Result(NegotiatorState.ready);
       case ScramState.challengeResponseSent:
         if (nonza.tag != 'success') {
           // We assume it's a <failure />
           final error = nonza.children.first.tag;
           await attributes.sendEvent(AuthenticationFailedEvent(error));
           _scramState = ScramState.error;
-          state = NegotiatorState.error;
-          return;
+          return Result(SaslFailedError());
         }
 
         // NOTE: This assumes that the string is always "v=..." and contains no other parameters
@@ -248,16 +246,13 @@ class SaslScramNegotiator extends SaslNegotiator {
           //final error = nonza.children.first.tag;
           //attributes.sendEvent(AuthenticationFailedEvent(error));
           _scramState = ScramState.error;
-          state = NegotiatorState.error;
-          return;
+          return Result(SaslFailedError());
         }
 
         await attributes.sendEvent(AuthenticationSuccessEvent());
-        state = NegotiatorState.done;
-        return;
+        return const Result(NegotiatorState.done);
       case ScramState.error:
-        state = NegotiatorState.error;
-        return;
+        return Result(SaslFailedError());
     }
   }
 

packages/moxxmpp/lib/src/negotiators/starttls.dart

@@ -3,12 +3,15 @@ import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 
 enum _StartTlsState {
   ready,
   requested
 }
 
+class StartTLSFailedError extends NegotiatorError {}
+
 class StartTLSNonza extends XMLNode {
   StartTLSNonza() : super.xmlns(
     tag: 'starttls',
@@ -27,18 +30,17 @@ class StartTlsNegotiator extends XmppFeatureNegotiatorBase {
   final Logger _log;
 
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     switch (_state) {
       case _StartTlsState.ready:
         _log.fine('StartTLS is available. Performing StartTLS upgrade...');
         _state = _StartTlsState.requested;
         attributes.sendNonza(StartTLSNonza());
-        break;
+        return const Result(NegotiatorState.ready);
       case _StartTlsState.requested:
         if (nonza.tag != 'proceed' || nonza.attributes['xmlns'] != startTlsXmlns) {
           _log.severe('Failed to perform StartTLS negotiation');
-          state = NegotiatorState.error;
-          return;
+          return Result(StartTLSFailedError());
         }
 
         _log.fine('Securing socket');
@@ -46,13 +48,11 @@ class StartTlsNegotiator extends XmppFeatureNegotiatorBase {
           .secure(attributes.getConnectionSettings().jid.domain);
         if (!result) {
           _log.severe('Failed to secure stream');
-          state = NegotiatorState.error;
-          return;
+          return Result(StartTLSFailedError());
         }
 
         _log.fine('Stream is now TLS secured');
-        state = NegotiatorState.done;
-        break;
+        return const Result(NegotiatorState.done);
     }
   }
 

packages/moxxmpp/lib/src/reconnect.dart

@@ -80,10 +80,11 @@ abstract class ReconnectionPolicy {
 /// for every failed attempt.
 class ExponentialBackoffReconnectionPolicy extends ReconnectionPolicy {
 
-  ExponentialBackoffReconnectionPolicy()
+  ExponentialBackoffReconnectionPolicy(this._maxBackoffTime)
   : _counter = 0,
     _log = Logger('ExponentialBackoffReconnectionPolicy'),
     super();
+  final int _maxBackoffTime;
   int _counter;
   Timer? _timer;
   final Logger _log;
@@ -124,7 +125,7 @@ class ExponentialBackoffReconnectionPolicy extends ReconnectionPolicy {
     }
 
     // Wait at max 80 seconds.
-    final seconds = min(pow(2, _counter).toInt(), 80);
+    final seconds = min(min(pow(2, _counter).toInt(), 80), _maxBackoffTime);
     _timer = Timer(Duration(seconds: seconds), _onTimerElapsed);
   }
 

packages/moxxmpp/lib/src/roster/errors.dart

@@ -0,0 +1,7 @@
+abstract class RosterError {}
+
+/// Returned when the server's response did not contain a <query /> element
+class NoQueryError extends RosterError {}
+
+/// Unspecified error
+class UnknownError extends RosterError {}

packages/moxxmpp/lib/src/roster/roster.dart

@@ -7,15 +7,12 @@ import 'package:moxxmpp/src/managers/namespaces.dart';
 import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
+import 'package:moxxmpp/src/roster/errors.dart';
 import 'package:moxxmpp/src/stanza.dart';
 import 'package:moxxmpp/src/stringxml.dart';
-import 'package:moxxmpp/src/types/error.dart';
-
-const rosterErrorNoQuery = 1;
-const rosterErrorNonResult = 2;
+import 'package:moxxmpp/src/types/result.dart';
 
 class XmppRosterItem {
-
   XmppRosterItem({ required this.jid, required this.subscription, this.ask, this.name, this.groups = const [] });
   final String jid;
   final String? name;
@@ -31,14 +28,12 @@ enum RosterRemovalResult {
 }
 
 class RosterRequestResult {
-
   RosterRequestResult({ required this.items, this.ver });
   List<XmppRosterItem> items;
   String? ver;
 }
 
 class RosterPushEvent extends XmppEvent {
-
   RosterPushEvent({ required this.item, this.ver });
   final XmppRosterItem item;
   final String? ver;
@@ -53,11 +48,11 @@ class RosterFeatureNegotiator extends XmppFeatureNegotiatorBase {
   bool get isSupported => _supported;
   
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     // negotiate is only called when the negotiator matched, meaning the server
     // advertises roster versioning.
     _supported = true;
-    state = NegotiatorState.done;
+    return const Result(NegotiatorState.done);
   }
 
   @override
@@ -148,7 +143,7 @@ class RosterManager extends XmppManagerBase {
 
   /// Shared code between requesting rosters without and with roster versioning, if
   /// the server deems a regular roster response more efficient than n roster pushes.
-  Future<MayFail<RosterRequestResult>> _handleRosterResponse(XMLNode? query) async {
+  Future<Result<RosterRequestResult, RosterError>> _handleRosterResponse(XMLNode? query) async {
     final List<XmppRosterItem> items;
     if (query != null) {
       items = query.children.map((item) => XmppRosterItem(
@@ -166,7 +161,7 @@ class RosterManager extends XmppManagerBase {
       }
     } else {
       logger.warning('Server response to roster request without roster versioning does not contain a <query /> element, while the type is not error. This violates RFC6121');
-      return MayFail.failure(rosterErrorNoQuery);
+      return Result(NoQueryError());
     }
 
     final ver = query.attributes['ver'] as String?;
@@ -175,7 +170,7 @@ class RosterManager extends XmppManagerBase {
       await commitLastRosterVersion(ver);
     }
     
-    return MayFail.success(
+    return Result(
       RosterRequestResult(
         items: items,
         ver: ver,
@@ -185,7 +180,7 @@ class RosterManager extends XmppManagerBase {
   }
   
   /// Requests the roster following RFC 6121 without using roster versioning.
-  Future<MayFail<RosterRequestResult>> requestRoster() async {
+  Future<Result<RosterRequestResult, RosterError>> requestRoster() async {
     final attrs = getAttributes();
     final response = await attrs.sendStanza(
       Stanza.iq(
@@ -201,7 +196,7 @@ class RosterManager extends XmppManagerBase {
 
     if (response.attributes['type'] != 'result') {
       logger.warning('Error requesting roster without roster versioning: ${response.toXml()}');
-      return MayFail.failure(rosterErrorNonResult);
+      return Result(UnknownError());
     }
 
     final query = response.firstTag('query', xmlns: rosterXmlns);
@@ -210,7 +205,7 @@ class RosterManager extends XmppManagerBase {
 
   /// Requests a series of roster pushes according to RFC6121. Requires that the server
   /// advertises urn:xmpp:features:rosterver in the stream features.
-  Future<MayFail<RosterRequestResult?>> requestRosterPushes() async {
+  Future<Result<RosterRequestResult?, RosterError>> requestRosterPushes() async {
     if (_rosterVersion == null) {
       await loadLastRosterVersion();
     }
@@ -233,7 +228,7 @@ class RosterManager extends XmppManagerBase {
 
     if (result.attributes['type'] != 'result') {
       logger.warning('Requesting roster pushes failed: ${result.toXml()}');
-      return MayFail.failure(rosterErrorNonResult);
+      return Result(UnknownError());
     }
 
     final query = result.firstTag('query', xmlns: rosterXmlns);

packages/moxxmpp/lib/src/types/error.dart

@@ -1,19 +0,0 @@
-/// A wrapper class that can be used to indicate that a function may return a valid
-/// instance of [T] but may also fail.
-/// The way [MayFail] is intended to be used to to have function specific - or application
-/// specific - error codes that can be either handled by code or be translated into a
-/// localised error message for the user.
-class MayFail<T> {
-
-  MayFail({ this.result, this.errorCode });
-  MayFail.success(this.result);
-  MayFail.failure(this.errorCode);
-  T? result;
-  int? errorCode;
-
-  bool isError() => result == null && errorCode != null;
-
-  T getValue() => result!;
-
-  int getErrorCode() => errorCode!;
-}

packages/moxxmpp/lib/src/xeps/xep_0198/negotiator.dart

@@ -5,6 +5,7 @@ import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 import 'package:moxxmpp/src/xeps/xep_0198/nonzas.dart';
 import 'package:moxxmpp/src/xeps/xep_0198/state.dart';
 import 'package:moxxmpp/src/xeps/xep_0198/xep_0198.dart';
@@ -23,7 +24,6 @@ enum _StreamManagementNegotiatorState {
 ///       StreamManagementManager at least once before connecting, if stream resumption
 ///       is wanted.
 class StreamManagementNegotiator extends XmppFeatureNegotiatorBase {
-  
   StreamManagementNegotiator()
     : _state = _StreamManagementNegotiatorState.ready,
       _supported = false,
@@ -59,7 +59,7 @@ class StreamManagementNegotiator extends XmppFeatureNegotiatorBase {
   }
       
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     // negotiate is only called when we matched the stream feature, so we know
     // that the server advertises it.
     _supported = true;
@@ -80,7 +80,8 @@ class StreamManagementNegotiator extends XmppFeatureNegotiatorBase {
           _state = _StreamManagementNegotiatorState.enableRequested;
           attributes.sendNonza(StreamManagementEnableNonza());
         }
-        break;
+
+        return const Result(NegotiatorState.ready);
         case _StreamManagementNegotiatorState.resumeRequested:
           if (nonza.tag == 'resumed') {
             _log.finest('Stream Management resumption successful');
@@ -97,7 +98,7 @@ class StreamManagementNegotiator extends XmppFeatureNegotiatorBase {
 
             _resumeFailed = false;
             _isResumed = true;
-            state = NegotiatorState.skipRest;
+            return const Result(NegotiatorState.skipRest);
           } else {
             // We assume it is <failed />
             _log.info('Stream resumption failed. Expected <resumed />, got ${nonza.tag}, Proceeding with new stream...');
@@ -113,9 +114,8 @@ class StreamManagementNegotiator extends XmppFeatureNegotiatorBase {
             _resumeFailed = true;
             _isResumed = false;
             _state = _StreamManagementNegotiatorState.ready;
-            state = NegotiatorState.retryLater;
+            return const Result(NegotiatorState.retryLater);
           }
-        break;
       case _StreamManagementNegotiatorState.enableRequested:
         if (nonza.tag == 'enabled') {
           _log.finest('Stream Management enabled');
@@ -133,14 +133,12 @@ class StreamManagementNegotiator extends XmppFeatureNegotiatorBase {
             ),
           );
 
-          state = NegotiatorState.done;
+          return const Result(NegotiatorState.done);
         } else {
           // We assume a <failed />
           _log.warning('Stream Management enablement failed');
-          state = NegotiatorState.done;
+          return const Result(NegotiatorState.done);
         }
-
-        break;
     }
   }
 

packages/moxxmpp/lib/src/xeps/xep_0352.dart

@@ -4,6 +4,7 @@ import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/namespaces.dart';
 import 'package:moxxmpp/src/negotiators/negotiator.dart';
 import 'package:moxxmpp/src/stringxml.dart';
+import 'package:moxxmpp/src/types/result.dart';
 
 class CSIActiveNonza extends XMLNode {
   CSIActiveNonza() : super(
@@ -32,11 +33,11 @@ class CSINegotiator extends XmppFeatureNegotiatorBase {
   bool get isSupported => _supported;
   
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     // negotiate is only called when the negotiator matched, meaning the server
     // advertises CSI.
     _supported = true;
-    state = NegotiatorState.done;
+    return const Result(NegotiatorState.done);
   }
 
   @override

packages/moxxmpp/lib/src/xeps/xep_0363/errors.dart

@@ -0,0 +1,10 @@
+abstract class HttpFileUploadError {}
+
+/// Returned when we don't know what JID to ask for an upload slot
+class NoEntityKnownError extends HttpFileUploadError {}
+
+/// Returned when the file we want to upload is too big
+class FileTooBigError extends HttpFileUploadError {}
+
+/// Unspecified errors
+class UnknownHttpFileUploadError extends HttpFileUploadError {}

packages/moxxmpp/lib/src/xeps/xep_0363/xep_0363.dart

@@ -7,19 +7,15 @@ import 'package:moxxmpp/src/managers/namespaces.dart';
 import 'package:moxxmpp/src/namespaces.dart';
 import 'package:moxxmpp/src/stanza.dart';
 import 'package:moxxmpp/src/stringxml.dart';
-import 'package:moxxmpp/src/types/error.dart';
+import 'package:moxxmpp/src/types/result.dart';
 import 'package:moxxmpp/src/xeps/xep_0030/errors.dart';
 import 'package:moxxmpp/src/xeps/xep_0030/types.dart';
 import 'package:moxxmpp/src/xeps/xep_0030/xep_0030.dart';
-
-const errorNoUploadServer = 1;
-const errorFileTooBig = 2;
-const errorGeneric = 3;
+import 'package:moxxmpp/src/xeps/xep_0363/errors.dart';
 
 const allowedHTTPHeaders = [ 'authorization', 'cookie', 'expires' ];
 
 class HttpFileUploadSlot {
-
   const HttpFileUploadSlot(this.putUrl, this.getUrl, this.headers);
   final String putUrl;
   final String getUrl;
@@ -45,7 +41,6 @@ Map<String, String> prepareHeaders(Map<String, String> headers) {
 }
 
 class HttpFileUploadManager extends XmppManagerBase {
-
   HttpFileUploadManager() : _gotSupported = false, _supported = false, super();
   JID? _entityJid;
   int? _maxUploadSize;
@@ -119,17 +114,17 @@ class HttpFileUploadManager extends XmppManagerBase {
   /// the file's size in octets. [contentType] is optional and refers to the file's
   /// Mime type.
   /// Returns an [HttpFileUploadSlot] if the request was successful; null otherwise.
-  Future<MayFail<HttpFileUploadSlot>> requestUploadSlot(String filename, int filesize, { String? contentType }) async {
-    if (!(await isSupported())) return MayFail.failure(errorNoUploadServer);
+  Future<Result<HttpFileUploadSlot, HttpFileUploadError>> requestUploadSlot(String filename, int filesize, { String? contentType }) async {
+    if (!(await isSupported())) return Result(NoEntityKnownError());
 
     if (_entityJid == null) {
       logger.warning('Attempted to request HTTP File Upload slot but no entity is known to send this request to.');
-      return MayFail.failure(errorNoUploadServer);
+      return Result(NoEntityKnownError());
     }
 
     if (_maxUploadSize != null && filesize > _maxUploadSize!) {
       logger.warning('Attempted to request HTTP File Upload slot for a file that exceeds the filesize limit');
-      return MayFail.failure(errorFileTooBig);
+      return Result(FileTooBigError());
     }
     
     final attrs = getAttributes();
@@ -154,7 +149,7 @@ class HttpFileUploadManager extends XmppManagerBase {
     if (response.attributes['type']! != 'result') {
       logger.severe('Failed to request HTTP File Upload slot.');
       // TODO(Unknown): Be more precise
-      return MayFail.failure(errorGeneric);
+      return Result(UnknownHttpFileUploadError());
     }
 
     final slot = response.firstTag('slot', xmlns: httpFileUploadXmlns)!;
@@ -169,7 +164,7 @@ class HttpFileUploadManager extends XmppManagerBase {
       }),
     );
 
-    return MayFail.success(
+    return Result(
       HttpFileUploadSlot(
         putUrl,
         getUrl,

packages/moxxmpp/lib/src/xeps/xep_0384/xep_0384.dart

@@ -44,7 +44,6 @@ const _doNotEncryptList = [
 ];
 
 abstract class OmemoManager extends XmppManagerBase {
-
   OmemoManager() : _handlerLock = Lock(), _handlerFutures = {}, super();
 
   final Lock _handlerLock;

packages/moxxmpp/test/negotiator_test.dart

@@ -3,10 +3,10 @@ import 'package:test/test.dart';
 import 'helpers/logging.dart';
 import 'helpers/xmpp.dart';
 
-const exampleXmlns1 = 'im:moxxy:example1';
-const exampleNamespace1 = 'im.moxxy.test.example1';
-const exampleXmlns2 = 'im:moxxy:example2';
-const exampleNamespace2 = 'im.moxxy.test.example2';
+const exampleXmlns1 = 'im:moxxmpp:example1';
+const exampleNamespace1 = 'im.moxxmpp.test.example1';
+const exampleXmlns2 = 'im:moxxmpp:example2';
+const exampleNamespace2 = 'im.moxxmpp.test.example2';
 
 class StubNegotiator1 extends XmppFeatureNegotiatorBase {
   StubNegotiator1() : called = false, super(1, false, exampleXmlns1, exampleNamespace1);
@@ -14,9 +14,9 @@ class StubNegotiator1 extends XmppFeatureNegotiatorBase {
   bool called;
   
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     called = true;
-    state = NegotiatorState.done;
+    return const Result(NegotiatorState.done);
   }
 }
 
@@ -26,9 +26,9 @@ class StubNegotiator2 extends XmppFeatureNegotiatorBase {
   bool called;
   
   @override
-  Future<void> negotiate(XMLNode nonza) async {
+  Future<Result<NegotiatorState, NegotiatorError>> negotiate(XMLNode nonza) async {
     called = true;
-    state = NegotiatorState.done;
+    return const Result(NegotiatorState.done);
   }
 }
 
@@ -47,8 +47,8 @@ void main() {
     from="test.server"
     xml:lang="en">
   <stream:features xmlns="http://etherx.jabber.org/streams">
-    <example1 xmlns="im:moxxy:example1" />
-    <example2 xmlns="im:moxxy:example2" />
+    <example1 xmlns="im:moxxmpp:example1" />
+    <example2 xmlns="im:moxxmpp:example2" />
   </stream:features>''',
       ),
     ],

packages/moxxmpp/test/sasl/scram_test.dart

@@ -128,9 +128,9 @@ void main() {
         'c=biws,r=rOprNGfwEbeRWgbNEkqO%hvYDpWUa2RaTCAfuxFIlj)hNlF\$k0,p=dHzbZapWIk4jUhN+Ute9ytag9zjfMHgsqmmiz7AndVQ=',
       );
 
-      await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj02cnJpVFJCaTIzV3BSUi93dHVwK21NaFVaVW4vZEI1bkxUSlJzamw5NUc0PQ==</success>"));
+      final result = await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj02cnJpVFJCaTIzV3BSUi93dHVwK21NaFVaVW4vZEI1bkxUSlJzamw5NUc0PQ==</success>"));
 
-      expect(negotiator.state, NegotiatorState.done);
+      expect(result.get<NegotiatorState>(), NegotiatorState.done);
   });
   
   test('Test a positive server signature check', () async {
@@ -150,9 +150,9 @@ void main() {
 
       await negotiator.negotiate(scramSha1StreamFeatures);
       await negotiator.negotiate(XMLNode.fromString("<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>cj1meWtvK2QybGJiRmdPTlJ2OXFreGRhd0wzcmZjTkhZSlkxWlZ2V1ZzN2oscz1RU1hDUitRNnNlazhiZjkyLGk9NDA5Ng==</challenge>"));
-      await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1ybUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
+      final result = await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1ybUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
 
-      expect(negotiator.state, NegotiatorState.done);
+      expect(result.get<NegotiatorState>(), NegotiatorState.done);
   });
 
   test('Test a negative server signature check', () async {
@@ -170,11 +170,15 @@ void main() {
         ),
       );
 
-      await negotiator.negotiate(scramSha1StreamFeatures);
-      await negotiator.negotiate(XMLNode.fromString("<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>cj1meWtvK2QybGJiRmdPTlJ2OXFreGRhd0wzcmZjTkhZSlkxWlZ2V1ZzN2oscz1RU1hDUitRNnNlazhiZjkyLGk9NDA5Ng==</challenge>"));
-      await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1zbUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
+      var result;
+      result = await negotiator.negotiate(scramSha1StreamFeatures);
+      expect(result.isType<NegotiatorState>(), true);
 
-      expect(negotiator.state, NegotiatorState.error);
+      result = await negotiator.negotiate(XMLNode.fromString("<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>cj1meWtvK2QybGJiRmdPTlJ2OXFreGRhd0wzcmZjTkhZSlkxWlZ2V1ZzN2oscz1RU1hDUitRNnNlazhiZjkyLGk9NDA5Ng==</challenge>"));
+      expect(result.isType<NegotiatorState>(), true);
+
+      result = await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1zbUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
+      expect(result.isType<NegotiatorError>(), true);
   });
 
   test('Test a resetting the SCRAM negotiator', () async {
@@ -194,14 +198,14 @@ void main() {
 
       await negotiator.negotiate(scramSha1StreamFeatures);
       await negotiator.negotiate(XMLNode.fromString("<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>cj1meWtvK2QybGJiRmdPTlJ2OXFreGRhd0wzcmZjTkhZSlkxWlZ2V1ZzN2oscz1RU1hDUitRNnNlazhiZjkyLGk9NDA5Ng==</challenge>"));
-      await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1ybUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
-      expect(negotiator.state, NegotiatorState.done);
+      final result1 = await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1ybUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
+      expect(result1.get<NegotiatorState>(), NegotiatorState.done);
 
       // Reset and try again
       negotiator.reset();
       await negotiator.negotiate(scramSha1StreamFeatures);
       await negotiator.negotiate(XMLNode.fromString("<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>cj1meWtvK2QybGJiRmdPTlJ2OXFreGRhd0wzcmZjTkhZSlkxWlZ2V1ZzN2oscz1RU1hDUitRNnNlazhiZjkyLGk9NDA5Ng==</challenge>"));
-      await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1ybUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
-      expect(negotiator.state, NegotiatorState.done);
+      final result2 = await negotiator.negotiate(XMLNode.fromString("<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>dj1ybUY5cHFWOFM3c3VBb1pXamE0ZEpSa0ZzS1E9</success>"));
+      expect(result2.get<NegotiatorState>(), NegotiatorState.done);
   });
 }