Include file path in JSON error when possible.

sdk/lib/_internal/pub/test/pub_uploader_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.
 
 library pub_uploader_test;
 
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:shelf/shelf.dart' as shelf;
 
 import '../lib/src/exit_codes.dart' as exit_codes;
-import '../lib/src/io.dart';
 import '../lib/src/utils.dart';
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
 final USAGE_STRING = '''
 Manage uploaders for a package on pub.dartlang.org.
 
 Usage: pub uploader [options] {add/remove} <email>
 -h, --help       Print usage information for this command.
     --server     The package server on which the package is hosted.
@@ skipping 70 matching lines @@
     d.validPackage.create();
 
     var server = new ScheduledServer();
     d.credentialsFile(server, 'access token').create();
     var pub = startPubUploader(server, ['add', 'email']);
 
     server.handle('POST', '/api/packages/test_pkg/uploaders', (request) {
       return new shelf.Response.ok(JSON.encode({
         'success': {'message': 'Good job!'}
       }), headers: {'content-type': 'application/json'});
-      request.response.close();
     });
 
     pub.stdout.expect('Good job!');
     pub.shouldExit(exit_codes.SUCCESS);
   });
 
   integration('add provides an error', () {
     var server = new ScheduledServer();
     d.credentialsFile(server, 'access token').create();
     var pub = startPubUploader(server, ['--package', 'pkg', 'add', 'email']);
@@ skipping 45 matching lines @@
 
     server.handle('DELETE', '/api/packages/pkg/uploaders/email',
         (request) => new shelf.Response.ok("{not json"));
 
     pub.stderr.expect(emitsLines(
         'Invalid server response:\n'
         '{not json'));
     pub.shouldExit(1);
   });
 }