Fix various pub issues.

test/packages_file_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS d.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 d.file.
 
+import 'package:pub/src/exit_codes.dart' as exit_codes;
+
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
 main() {
   forBothPubGetAndUpgrade((command) {
     integration('.packages file is created', () {
       servePackages((builder) {
         builder.serve("foo", "1.2.3",
             deps: {'baz': '2.2.2'}, contents: [d.dir("lib", [])]);
         builder.serve("bar", "3.2.1", contents: [d.dir("lib", [])]);
@@ skipping 38 matching lines @@
        .validate();
     });
 
     integration('.packages file is not created if pub command fails', () {
       d.dir(appPath, [
         d.appPubspec({"foo": "1.2.3"}),
         d.dir('lib')
       ]).create();
 
       pubCommand(command, args: ['--offline'],
-                 error: "Could not find package foo in cache.\n");
+          error: "Could not find package foo in cache.\n"
+                 "Depended on by:\n"
+                 "- myapp",
+          exitCode: exit_codes.UNAVAILABLE);
 
       d.dir(appPath, [d.nothing('.packages')]).validate();
     });
 
     integration('.packages file has relative path to path dependency', () {
       servePackages((builder) {
         builder.serve("foo", "1.2.3",
             deps: {'baz': 'any'}, contents: [d.dir("lib", [])]);
         builder.serve("baz", "9.9.9",
             deps: {}, contents: [d.dir("lib", [])]);
@@ skipping 19 matching lines @@
 
       d.dir(appPath, [
         d.packagesFile({
           "myapp": ".",
           "baz": "../local_baz"
         })
       ]).validate();
     });
   });
 }