add --preview flag to publish command

utils/pub/command_lish.dart

Index: utils/pub/command_lish.dart
===================================================================
--- utils/pub/command_lish.dart	(revision 18263)
+++ utils/pub/command_lish.dart	(working copy)
@@ -32,6 +32,8 @@
     var parser = new ArgParser();
     // TODO(nweiz): Use HostedSource.defaultUrl as the default value once we use
     // dart:io for HTTPS requests.
+    parser.addFlag('preview', abbr: 'p', negatable: false,
+        help: 'Preview publishing the package');

[nweiz, 2013/02/09 00:20:50]

Weren't we going to call this --dry-run?

[keertip, 2013/02/09 00:53:40]

Not sure what we settled on in the end, but am OK with what you and Bob decide.

On 2013/02/09 00:20:50, nweiz wrote:

[nweiz, 2013/02/09 00:59:02]

I'd prefer --dry-run, since that's consistent with Git and other command-line
tools. Bob isn't here to give his opinion, but I think he agreed last time we
talked about this.

[keertip, 2013/02/09 04:05:47]

Done.

     parser.addOption('server', defaultsTo: 'https://pub.dartlang.org',
         help: 'The package server to which to upload this package');
     return parser;
@@ -164,6 +166,11 @@
         var s = warnings.length == 1 ? '' : 's';
         message = "Package has ${warnings.length} warning$s. Upload anyway";
       }
+      
+      if (commandOptions['preview']){
+        log.warning("Package has ${warnings.length} warnings.");

[nweiz, 2013/02/09 00:20:50]

Nit: it would be nice to do the pluralization trick we do above so it doesn't
say "1 warnings".

[keertip, 2013/02/09 00:53:40]

Done.

+        exit(0);
+      }

[nweiz, 2013/02/09 00:20:50]

Style nit: I'd move this block above the message assignment.

[keertip, 2013/02/09 00:53:40]

Done.

 
       return confirm(message).then((confirmed) {
         if (!confirmed) throw "Package upload canceled.";