Remove usage of dart:json.

pkg/oauth2/test/handle_access_token_response_test.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.
 
 library handle_access_token_response_test;
 
-import 'dart:json' as JSON;
+import 'dart:convert';
 
 import 'package:http/http.dart' as http;
 import 'package:oauth2/oauth2.dart' as oauth2;
 import 'package:oauth2/src/handle_access_token_response.dart';
 import 'package:unittest/unittest.dart';
 
 import 'utils.dart';
 
 final Uri tokenEndpoint = Uri.parse("https://example.com/token");
 
@@ skipping 45 matching lines @@
       expect(() => handleError(body: 'not json'),
           throwsFormatException);
     });
 
     test('with a non-string error causes a FormatException', () {
       expect(() => handleError(body: '{"error": 12}'),
           throwsFormatException);
     });
 
     test('with a non-string error_description causes a FormatException', () {
-      expect(() => handleError(body: JSON.stringify({
+      expect(() => handleError(body: JSON.encode({
         "error": "invalid_request",
         "error_description": 12
       })), throwsFormatException);
     });
 
     test('with a non-string error_uri causes a FormatException', () {
-      expect(() => handleError(body: JSON.stringify({
+      expect(() => handleError(body: JSON.encode({
         "error": "invalid_request",
         "error_uri": 12
       })), throwsFormatException);
     });
 
     test('with a string error_description causes a AuthorizationException', () {
-      expect(() => handleError(body: JSON.stringify({
+      expect(() => handleError(body: JSON.encode({
         "error": "invalid_request",
         "error_description": "description"
       })), throwsAuthorizationException);
     });
 
     test('with a string error_uri causes a AuthorizationException', () {
-      expect(() => handleError(body: JSON.stringify({
+      expect(() => handleError(body: JSON.encode({
         "error": "invalid_request",
         "error_uri": "http://example.com/error"
       })), throwsAuthorizationException);
     });
   });
 
   group('a success response', () {
     oauth2.Credentials handleSuccess(
         {String contentType: "application/json",
          accessToken: 'access token',
          tokenType: 'bearer',
          expiresIn,
          refreshToken,
          scope}) {
-      return handle(new http.Response(JSON.stringify({
+      return handle(new http.Response(JSON.encode({
         'access_token': accessToken,
         'token_type': tokenType,
         'expires_in': expiresIn,
         'refresh_token': refreshToken,
         'scope': scope
       }), 200, headers: {'content-type': contentType}));
     }
 
     test('returns the correct credentials', () {
       var credentials = handleSuccess();
@@ skipping 61 matching lines @@
     test('with a non-string scope throws a FormatException', () {
       expect(() => handleSuccess(scope: 12), throwsFormatException);
     });
 
     test('with a scope sets the scopes', () {
       var credentials = handleSuccess(scope: "scope1 scope2");
       expect(credentials.scopes, equals(["scope1", "scope2"]));
     });
   });
 }