feat(client): websocket usable on browser

packages/graphql/lib/src/link/web_socket/link_web_socket.dart

@@ -2,6 +2,7 @@ import 'package:graphql/src/link/fetch_result.dart';
 import 'package:graphql/src/link/link.dart';
 import 'package:graphql/src/link/operation.dart';
 import 'package:graphql/src/socket_client.dart';
+import 'package:graphql/src/utilities/platform.dart' show isHtml;
 import 'package:graphql/src/websocket/messages.dart';
 import 'package:meta/meta.dart';
 
@@ -22,13 +23,32 @@ class WebSocketLink extends Link {
   /// Creates a new [WebSocketLink] instance with the specified config.
   WebSocketLink(
       {@required this.url,
+      @deprecated
+      // ignore: deprecated_member_use_from_same_package
+      this.headers,
       this.reconnectOnHeaderChange = true,
       this.config = const SocketClientConfig()})
       : super() {
+    if (headers != null) {
+      assert(
+        !isHtml,
+        'Cannot set websocket headers with dart:html websockets. '
+        'If these are for authentication, another approach must be used, '
+        'such as initPayload.',
+      );
+      print(
+        'WARNING: Using direct websocket headers which will be removed soon, '
+        'as it is incompatable with dart:html. '
+        'If you need this direct header access, '
+        'please comment on this PR with details on your usecase: '
+        'https://github.com/zino-app/graphql-flutter/pull/323',
+      );
+    }
     request = _doOperation;
   }
 
   final String url;
+  final Map<String, dynamic> headers;
   final bool reconnectOnHeaderChange;
   final SocketClientConfig config;
 
@@ -41,6 +61,10 @@ class WebSocketLink extends Link {
     if (context != null && context.containsKey('headers')) {
       concatHeaders.addAll(context['headers'] as Map<String, dynamic>);
     }
+    // @todo deprecated
+    if (headers != null) {
+      concatHeaders.addAll(headers);
+    }
 
     if (_socketClient == null) {
       connectOrReconnect(headers: concatHeaders);
@@ -57,8 +81,7 @@ class WebSocketLink extends Link {
   /// Connects or reconnects to the server with the specified headers.
   void connectOrReconnect({Map<String, dynamic> headers}) {
     _socketClient?.dispose();
-    _socketClient =
-        SocketClient(url, config: config);
+    _socketClient = SocketClient(url, config: config);
   }
 
   /// Disposes the underlying socket client explicitly. Only use this, if you want to disconnect from

packages/graphql/lib/src/utilities/platform.dart

@@ -0,0 +1,3 @@
+export './platform_stub.dart'
+    if (dart.library.html) './platform_html.dart'
+    if (dart.library.io) './platform_io.dart';

packages/graphql/lib/src/utilities/platform_html.dart

@@ -0,0 +1,2 @@
+final isHtml = true;
+final isIo = false;

packages/graphql/lib/src/utilities/platform_io.dart

@@ -0,0 +1,2 @@
+final isHtml = false;
+final isIo = true;

packages/graphql/lib/src/utilities/platform_stub.dart

@@ -0,0 +1,2 @@
+final isHtml = false;
+final isIo = false;

packages/graphql/test/helpers.dart

@@ -1,4 +1,5 @@
 // This
+import 'dart:async';
 import 'dart:mirrors';
 import 'dart:convert';
 import 'dart:io' show File, Directory;
@@ -9,6 +10,14 @@ import 'package:http/http.dart' as http;
 
 import 'package:graphql/client.dart';
 
+overridePrint(testFn(List<String> log)) => () {
+      final log = <String>[];
+      final spec = new ZoneSpecification(print: (_, __, ___, String msg) {
+        log.add(msg);
+      });
+      return Zone.current.fork(specification: spec).run(() => testFn(log));
+    };
+
 NormalizedInMemoryCache getTestCache() => NormalizedInMemoryCache(
       dataIdFromObject: typenameDataIdFromObject,
       storageProvider: () => Directory.systemTemp.createTemp('file_test_'),

packages/graphql/test/in_memory_storage_test.dart

@@ -3,6 +3,8 @@ import 'dart:io' show Directory, FileSystemException;
 import 'package:test/test.dart';
 import 'package:graphql/src/cache/in_memory.dart';
 
+import 'helpers.dart';
+
 const String aKey = 'aKey';
 const String bKey = 'bKey';
 const String cKey = 'cKey';
@@ -158,11 +160,3 @@ void main() {
     }));
   });
 }
-
-overridePrint(testFn(List<String> log)) => () {
-      final log = <String>[];
-      final spec = new ZoneSpecification(print: (_, __, ___, String msg) {
-        log.add(msg);
-      });
-      return Zone.current.fork(specification: spec).run(() => testFn(log));
-    };

packages/graphql/test/link_web_socket_test_html.dart

@@ -0,0 +1,18 @@
+@TestOn('browser')
+
+import 'package:test/test.dart';
+import 'package:graphql/src/link/web_socket/link_web_socket.dart';
+
+void main() {
+  group('Link Websocket', () {
+    test('simple connection', () {
+      expect(
+          () => WebSocketLink(
+                url: 'ws://echo.websocket.org',
+                // ignore: deprecated_member_use_from_same_package
+                headers: {'foo': 'bar'},
+              ),
+          throwsA(TypeMatcher<AssertionError>()));
+    });
+  });
+}

packages/graphql/test/link_web_socket_test_io.dart

@@ -0,0 +1,23 @@
+@TestOn('vm')
+
+import 'package:test/test.dart';
+import 'package:graphql/src/link/web_socket/link_web_socket.dart';
+
+import 'helpers.dart';
+
+void main() {
+  group('Link Websocket', () {
+    test('simple connection', overridePrint((List<String> log) {
+      WebSocketLink(
+        url: 'ws://echo.websocket.org',
+        // ignore: deprecated_member_use_from_same_package
+        headers: {'foo': 'bar'},
+      );
+      expect(log, [
+        'Cannot set websocket headers with dart:html websockets. '
+            'If these are for authentication, another approach must be used, '
+            'such as initPayload.'
+      ]);
+    }));
+  });
+}

packages/graphql_flutter/example/lib/graphql_widget/main.dart

@@ -26,7 +26,7 @@ class GraphQLWidgetScreen extends StatelessWidget {
       getToken: () async => 'Bearer $YOUR_PERSONAL_ACCESS_TOKEN',
     );
 
-    Link link = authLink.concat(httpLink);
+    Link link = authLink.concat(httpLink as Link);
     if (ENABLE_WEBSOCKETS) {
       final WebSocketLink websocketLink = WebSocketLink(
         url: 'ws://localhost:8080/ws/graphql',