add --preview flag to publish command

utils/tests/pub/pub_lish_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 pub_lish_test;
 
 import 'dart:io';
 import 'dart:json' as json;
 
 import 'test_pub.dart';
@@ skipping 63 matching lines @@
     expectLater(pub.nextLine(), equals(
         'Looks great! Are you ready to upload your package (y/n)?'
         ' Package test_pkg 1.0.0 uploaded!'));
     pub.shouldExit(0);
   });
 
   // TODO(nweiz): Once a multipart/form-data parser in Dart exists, we should
   // test that "pub lish" chooses the correct files to publish.
 
   integration('package validation has an error', () {
-    var package = package("test_pkg", "1.0.0");
-    package.remove("homepage");
-    dir(appPath, [pubspec(package)]).scheduleCreate();
+    var pkg = package("test_pkg", "1.0.0");
+    pkg.remove("homepage");
+    dir(appPath, [pubspec(pkg)]).scheduleCreate();
 
     var server = new ScheduledServer();
     var pub = startPubLish(server);
 
-    pub.shouldExit(1);
+    pub.shouldExit(0);
     expectLater(pub.remainingStderr(),
         contains("Sorry, your package is missing a requirement and can't be "
             "published yet."));
   });
 
+  integration('preview package validation has a warning', () {
+    var pkg = package("test_pkg", "1.0.0");
+    pkg["author"] = "Nathan Weizenbaum";
+    dir(appPath, [pubspec(pkg)]).scheduleCreate();
+
+    var server = new ScheduledServer();
+    var pub = startPubLish(server, args: ['--dry-run']);
+
+    pub.shouldExit(0);
+    expectLater(pub.remainingStderr(),
+        contains('Suggestions:\n* Author "Nathan Weizenbaum" in pubspec.yaml' 
+                  ' should have an email address\n'
+                  '  (e.g. "name <email>").\n\n'
+                  'Package has 1 warning.'));
+  });
+  
+  integration('preview package validation has no warnings', () {
+    var pkg = package("test_pkg", "1.0.0");
+    pkg["author"] = "Nathan Weizenbaum <nweiz@google.com>";
+    dir(appPath, [pubspec(pkg)]).scheduleCreate();
+
+    var server = new ScheduledServer();
+    var pub = startPubLish(server, args: ['--dry-run']);
+
+    pub.shouldExit(0);
+    expectLater(pub.remainingStderr(),
+        contains('Package has 0 warnings.'));
+  });
+  
   integration('package validation has a warning and is canceled', () {
-    var package = package("test_pkg", "1.0.0");
-    package["author"] = "Nathan Weizenbaum";
-    dir(appPath, [pubspec(package)]).scheduleCreate();
+    var pkg = package("test_pkg", "1.0.0");
+    pkg["author"] = "Nathan Weizenbaum";
+    dir(appPath, [pubspec(pkg)]).scheduleCreate();
 
     var server = new ScheduledServer();
     var pub = startPubLish(server);
 
     pub.writeLine("n");
-    pub.shouldExit(1);
+    pub.shouldExit(0);
     expectLater(pub.remainingStderr(), contains("Package upload canceled."));
   });
 
   integration('package validation has a warning and continues', () {
-    var package = package("test_pkg", "1.0.0");
-    package["author"] = "Nathan Weizenbaum";
-    dir(appPath, [pubspec(package)]).scheduleCreate();
+    var pkg = package("test_pkg", "1.0.0");
+    pkg["author"] = "Nathan Weizenbaum";
+    dir(appPath, [pubspec(pkg)]).scheduleCreate();
 
     var server = new ScheduledServer();
     credentialsFile(server, 'access token').scheduleCreate();
     var pub = startPubLish(server);
     pub.writeLine("y");
     handleUploadForm(server);
     handleUpload(server);
 
     server.handle('GET', '/create', (request, response) {
       response.outputStream.writeString(json.stringify({
@@ skipping 246 matching lines @@
     server.handle('GET', '/create', (request, response) {
       response.outputStream.writeString(json.stringify(body));
       response.outputStream.close();
     });
 
     expectLater(pub.nextErrLine(), equals('Invalid server response:'));
     expectLater(pub.nextErrLine(), equals(json.stringify(body)));
     pub.shouldExit(1);
   });
 }