ruby - Can bundler show me which gems in Gemfile have newer versions (eg. dry-run of bundle update)

Question

Is there a way to run bundle update in pretend mode, similar to the -p (pretend) flag for Rails generators or cap's -n (dry-run) flag?

I'm imagining something like:

$> bundle update -p
Fetching source index for http://rubygems.org/
The following gems have updated versions:
...
list of gems
...

Answer 1

Bundler 1.1 introduced a new 'outdated' feature, which is exactly what I was looking for. Pat Shaughnessy has a great write-up on the new features. In his words, bundle outdated:

displays the gems it would download and install, but without actually doing it. This gives me the freedom to inspect the list and update just the gems I would like to.

This should make it a snap to see what gems are due for an update without actually modifying your source and local gems. Thanks Bundler!