Add a validator for dependency version constraints.

utils/tests/pub/test_pub.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.
 
 /**
  * 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:io';
 import 'dart:isolate';
 import 'dart:json';
 import 'dart:math';
 import 'dart:uri';
 
 import '../../../pkg/oauth2/lib/oauth2.dart' as oauth2;
 import '../../../pkg/path/lib/path.dart' as path;
 import '../../../pkg/unittest/lib/unittest.dart';
+import '../../../pkg/http/lib/testing.dart';
 import '../../lib/file_system.dart' as fs;
 import '../../pub/entrypoint.dart';
 import '../../pub/git_source.dart';
 import '../../pub/hosted_source.dart';
+import '../../pub/http.dart';
 import '../../pub/io.dart';
 import '../../pub/sdk_source.dart';
 import '../../pub/system_cache.dart';
 import '../../pub/utils.dart';
 import '../../pub/validator.dart';
 import '../../pub/yaml/yaml.dart';
 
 /**
  * Creates a new [FileDescriptor] with [name] and [contents].
  */
@@ skipping 665 matching lines @@
     return isGitInstalled.transform((installed) {
       if (!installed &&
           !Platform.environment.containsKey('BUILDBOT_BUILDERNAME')) {
         _abortScheduled = true;
       }
       return null;
     });
   });
 }
 
+/// Use [client] as the mock HTTP client for this test.
+///
+/// Note that this will only affect HTTP requests made via http.dart in the
+/// parent process.
+void useMockClient(MockClient client) {
+  var oldInnerClient = httpClient.inner;
+  httpClient.inner = client;
+  _scheduleCleanup((_) {
+    httpClient.inner = oldInnerClient;
+  });
+}
+
 Future<Directory> _setUpSandbox() => createTempDir();
 
 Future _runScheduled(Directory parentDir, List<_ScheduledEvent> scheduled) {
   if (scheduled == null) return new Future.immediate(null);
   var iterator = scheduled.iterator();
 
   Future runNextEvent(_) {
     if (_abortScheduled || !iterator.hasNext) {
       _abortScheduled = false;
       scheduled.clear();
@@ skipping 945 matching lines @@
 /// calling [completion] is unnecessary.
 void expectLater(Future actual, matcher, {String reason,
     FailureHandler failureHandler, bool verbose: false}) {
   _schedule((_) {
     return actual.transform((value) {
       expect(value, matcher, reason: reason, failureHandler: failureHandler,
           verbose: false);
     });
   });
 }