Use the new test runner.

test/validator/sdk_constraint_test.dart

 // Copyright (c) 2014, 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:convert';
 
 import 'package:http/http.dart' as http;
 import 'package:http/testing.dart';
 import 'package:path/path.dart' as path;
 import 'package:pub/src/entrypoint.dart';
 import 'package:pub/src/validator.dart';
 import 'package:pub/src/validator/sdk_constraint.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 Validator sdkConstraint(Entrypoint entrypoint) =>
   new SdkConstraintValidator(entrypoint);
 
 main() {
-  initConfig();
-
   group('should consider a package valid if it', () {
     integration('has no SDK constraint', () {
       d.validPackage.create();
       expectNoValidationError(sdkConstraint);
     });
 
     integration('has an SDK constraint without ^', () {
       d.dir(appPath, [
         d.libPubspec("test_pkg", "1.0.0", sdk: ">=1.8.0 <2.0.0")
       ]).create();
       expectNoValidationError(sdkConstraint);
     });
   });
 
   test("should consider a package invalid if it has an SDK constraint with "
       "^", () {
     d.dir(appPath, [
       d.libPubspec("test_pkg", "1.0.0", sdk: "^1.8.0")
     ]).create();
     expect(schedulePackageValidation(sdkConstraint),
         completion(pairOf(anyElement(contains('">=1.8.0 <2.0.0"')), isEmpty)));
   });
 }