Report correct socket error and use HttpServer:close future in pub.

sdk/lib/_internal/pub/test/test_pub.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.
 
 /// Test infrastructure for testing pub. Unlike typical unit tests, most pub
 /// tests are integration tests that stage some stuff on the file system, run
 /// pub, and then validate the results. This library provides an API to build
 /// tests like that.
 library test_pub;
 
 import 'dart:async';
 import 'dart:collection' show Queue;
-import 'dart:io' hide sleep;
+import 'dart:io';
 import 'dart:json' as json;
 import 'dart:math';
 import 'dart:utf';
 
 import 'package:http/testing.dart';
 import 'package:oauth2/oauth2.dart' as oauth2;
 import 'package:path/path.dart' as path;
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:scheduled_test/scheduled_test.dart';
@@ skipping 106 matching lines @@
         return null;
       });
     });
   }, 'starting a server serving:\n${baseDir.describe()}');
 }
 
 /// Closes [_server]. Returns a [Future] that will complete after the [_server]
 /// is closed.
 Future _closeServer() {
   if (_server == null) return new Future.value();
-  _server.close();
+  var future = _server.close();
   _server = null;
   _portCompleterCache = null;
-  // TODO(nweiz): Remove this once issue 4155 is fixed. Pumping the event loop
-  // *seems* to be enough to ensure that the server is actually closed, but I'm
-  // putting this at 10ms to be safe.
-  return sleep(10);
+  return future;
 }
 
 /// `true` if the current test spins up an HTTP server.
 bool _hasServer = false;
 
 /// The [d.DirectoryDescriptor] describing the server layout of `/api/packages`
 /// on the test server.
 ///
 /// This contains metadata for packages that are being served via
 /// [servePackages]. It's `null` if [servePackages] has not yet been called for
@@ skipping 648 matching lines @@
   bool matches(item, Map matchState) {
     if (item is! Pair) return false;
     return _firstMatcher.matches(item.first, matchState) &&
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }