Sort pubspec.lock packages.

sdk/lib/_internal/pub/test/lock_file_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 lock_file_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:yaml/yaml.dart';
 
 import '../lib/src/lock_file.dart';
@@ skipping 141 matching lines @@
   foo:
     bonus: not used
     version: 1.2.3
     source: mock
     description: foo desc
 ''', sources);
       });
     });
 
     group('serialize()', () {
+      var lockfile;
+      setUp(() {
+        lockfile = new LockFile.empty();
+      });
+
       test('dumps the lockfile to YAML', () {
-        var lockfile = new LockFile.empty();
         lockfile.packages['foo'] = new PackageId(
             'foo', mockSource, new Version.parse('1.2.3'), 'foo desc');
         lockfile.packages['bar'] = new PackageId(
-            'foo', mockSource, new Version.parse('3.2.1'), 'bar desc');
+            'bar', mockSource, new Version.parse('3.2.1'), 'bar desc');
 
         expect(loadYaml(lockfile.serialize()), equals({
           'packages': {
             'foo': {
               'version': '1.2.3',
               'source': 'mock',
               'description': 'foo desc'
             },
             'bar': {
               'version': '3.2.1',
               'source': 'mock',
               'description': 'bar desc'
             }
           }
         }));
       });
+
+      test('lockfile is alphabetized by package name', () {
+        var testNames = ['baz', 'Qwe', 'Q', 'B', 'Bar', 'bar', 'foo'];
+        testNames.forEach((name) {
+          lockfile.packages[name] = new PackageId(name, mockSource,
+            new Version.parse('5.5.5'), '$name desc');
+        });
+
+        expect(lockfile.serialize(),
+          '# Generated by pub\n'
+          '# See http://pub.dartlang.org/doc/glossary.html#lockfile\n'
+          '\n'
+          '{"packages":{'
+          '"B":{"version":"5.5.5","source":"mock","description":"B desc"},'
+          '"Bar":{"version":"5.5.5","source":"mock","description":"Bar desc"},'
+          '"Q":{"version":"5.5.5","source":"mock","description":"Q desc"},'
+          '"Qwe":{"version":"5.5.5","source":"mock","description":"Qwe desc"},'
+          '"bar":{"version":"5.5.5","source":"mock","description":"bar desc"},'
+          '"baz":{"version":"5.5.5","source":"mock","description":"baz desc"},'
+          '"foo":{"version":"5.5.5","source":"mock","description":"foo desc"}}}'
+          '\n'
+        );
+      });
     });
   });
 }