Add a validator for dependency version constraints.

utils/pub/http.dart

 // Copyright (c) 2012, 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.
 
 /// Helpers for dealing with HTTP.
 library pub.http;
 
 import 'dart:io';
 import 'dart:json';
 
 // TODO(nweiz): Make this import better.
 import '../../pkg/http/lib/http.dart' as http;
 import 'curl_client.dart';
 import 'io.dart';
 import 'log.dart' as log;
 
 // TODO(nweiz): make this configurable
 /**
  * The amount of time in milliseconds to allow HTTP requests before assuming
  * they've failed.
  */
 final HTTP_TIMEOUT = 30 * 1000;
 
 /// An HTTP client that transforms 40* errors and socket exceptions into more
 /// user-friendly error messages.
 class PubHttpClient extends http.BaseClient {
-  final http.Client _inner;
+  http.Client inner;
 
   PubHttpClient([http.Client inner])
-    : _inner = inner == null ? new http.Client() : inner;
+    : this.inner = inner == null ? new http.Client() : inner;
 
   Future<http.StreamedResponse> send(http.BaseRequest request) {
     // TODO(rnystrom): Log request body when it's available and plaintext, but
     // not when it contains OAuth2 credentials.
 
     // TODO(nweiz): remove this when issue 4061 is fixed.
     var stackTrace;
     try {
       throw null;
     } catch (_, localStackTrace) {
       stackTrace = localStackTrace;
     }
 
     // TODO(nweiz): Ideally the timeout would extend to reading from the
     // response input stream, but until issue 3657 is fixed that's not feasible.
-    return timeout(_inner.send(request).chain((streamedResponse) {
+    return timeout(inner.send(request).chain((streamedResponse) {
       log.fine("Got response ${streamedResponse.statusCode} "
                "${streamedResponse.reasonPhrase}.");
 
       var status = streamedResponse.statusCode;
       // 401 responses should be handled by the OAuth2 client. It's very
       // unlikely that they'll be returned by non-OAuth2 requests.
       if (status < 400 || status == 401) {
         return new Future.immediate(streamedResponse);
       }
 
@@ skipping 72 matching lines @@
  * Exception thrown when an HTTP operation fails.
  */
 class PubHttpException implements Exception {
   final http.Response response;
 
   const PubHttpException(this.response);
 
   String toString() => 'HTTP error ${response.statusCode}: '
       '${response.reasonPhrase}';
 }