pkg/mime: Use pkg/test

test/mime_multipart_transformer_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // 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 'dart:math';
 
-import "package:unittest/unittest.dart";
+import "package:test/test.dart";
 import "package:mime/mime.dart";
 
 void _writeInChunks(List<int> data,
                     int chunkSize,
                     StreamController<List<int>> controller) {
   if (chunkSize == -1) chunkSize = data.length;
 
   int written = 0;
   for (int pos = 0; pos < data.length; pos += chunkSize) {
     int remaining = data.length - pos;
@@ skipping 437 matching lines @@
 \r
 Body2\r
 --xxx\r\n""";
   _testParse(message, "xxx", null, [null, null], true);
 }
 
 void main() {
   _testParseValid();
   _testParseInvalid();
 }