Fix unused imports

diff --git a/pkgs/stream_channel/test/disconnector_test.dart b/pkgs/stream_channel/test/disconnector_test.dart
index 09cdddc..d7fa885 100644
--- a/pkgs/stream_channel/test/disconnector_test.dart
+++ b/pkgs/stream_channel/test/disconnector_test.dart

@@ -3,10 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:convert';
-import 'dart:isolate';
 
-import 'package:async/async.dart';
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
@@ -110,4 +107,4 @@
       expect(() => channel.sink.addError("oh no"), throwsStateError);
     });
   });
-}
\ No newline at end of file
+}

diff --git a/pkgs/stream_channel/test/json_document_transformer_test.dart b/pkgs/stream_channel/test/json_document_transformer_test.dart
index 65a3497..4dd5ea7 100644
--- a/pkgs/stream_channel/test/json_document_transformer_test.dart
+++ b/pkgs/stream_channel/test/json_document_transformer_test.dart

@@ -8,8 +8,6 @@
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
-import 'utils.dart';
-
 void main() {
   var streamController;
   var sinkController;

diff --git a/pkgs/stream_channel/test/multi_channel_test.dart b/pkgs/stream_channel/test/multi_channel_test.dart
index 5be2505..0e58d38 100644
--- a/pkgs/stream_channel/test/multi_channel_test.dart
+++ b/pkgs/stream_channel/test/multi_channel_test.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:async';
-
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 

diff --git a/pkgs/stream_channel/test/stream_channel_controller_test.dart b/pkgs/stream_channel/test/stream_channel_controller_test.dart
index cf8a31b..7503387 100644
--- a/pkgs/stream_channel/test/stream_channel_controller_test.dart
+++ b/pkgs/stream_channel/test/stream_channel_controller_test.dart

@@ -2,13 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'dart:async';
-
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
-import 'utils.dart';
-
 void main() {
   group("asynchronously", () {
     var controller;

diff --git a/pkgs/stream_channel/test/stream_channel_test.dart b/pkgs/stream_channel/test/stream_channel_test.dart
index f525177..2a6566a 100644
--- a/pkgs/stream_channel/test/stream_channel_test.dart
+++ b/pkgs/stream_channel/test/stream_channel_test.dart

@@ -4,14 +4,11 @@
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:isolate';
 
 import 'package:async/async.dart';
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
 
-import 'utils.dart';
-
 void main() {
   var streamController;
   var sinkController;