Add --parseable (with --porcelain alias) to bundle outdated for min…

…imal output

- This flag changes the output of bundle outdated from:
```
  * activesupport (newest 3.0, installed 2.3.5, requested = 2.3.5) in groups "development, test"
```
to
```
activesupport (newest 3.0, installed 2.3.5, requested = 2.3.5)"
```
and removes the extraneous output relating to fetching gem metadata,
version metadata, git updates, and resolving dependencies.

- Addresses rubygems/bundler-features#85

lib/bundler/cli.rb

@@ -245,6 +245,8 @@ def binstubs(*gems)
       "Only list newer versions allowed by your Gemfile requirements"
     method_option "major", :type => :boolean, :banner => "Only list major newer versions"
     method_option "minor", :type => :boolean, :banner => "Only list at least minor newer versions"
+    method_option "parseable", :aliases => "--porcelain", :type => :boolean, :banner =>
+      "Use minimal formatting for more parseable output"
     def outdated(*gems)
       require "bundler/cli/outdated"
       Outdated.new(options, gems).run

lib/bundler/cli/outdated.rb

@@ -27,7 +27,13 @@ def run
       else
         definition = Bundler.definition(:gems => gems, :sources => sources)
       end
-      options["local"] ? definition.resolve_with_cache! : definition.resolve_remotely!
+
+      definition_resolution = proc { options["local"] ? definition.resolve_with_cache! : definition.resolve_remotely! }
+      if options[:parseable]
+        Bundler.ui.silence(&definition_resolution)
+      else
+        definition_resolution.call
+      end
 
       Bundler.ui.info ""
 
@@ -65,32 +71,40 @@ def run
         gem_outdated = Gem::Version.new(active_spec.version) > Gem::Version.new(current_spec.version)
         git_outdated = current_spec.git_version != active_spec.git_version
         if gem_outdated || git_outdated
-          if out_count == 0
-            if options["pre"]
-              Bundler.ui.info "Outdated gems included in the bundle (including pre-releases):"
-            else
-              Bundler.ui.info "Outdated gems included in the bundle:"
+          unless options[:parseable]
+            if out_count == 0
+              if options["pre"]
+                Bundler.ui.info "Outdated gems included in the bundle (including pre-releases):"
+              else
+                Bundler.ui.info "Outdated gems included in the bundle:"
+              end
             end
           end
 
           spec_version    = "#{active_spec.version}#{active_spec.git_version}"
           current_version = "#{current_spec.version}#{current_spec.git_version}"
           dependency_version = %(, requested #{dependency.requirement}) if dependency && dependency.specific?
 
-          if dependency
+          if dependency && !options[:parseable]
             groups = dependency.groups.join(", ")
             pl = (dependency.groups.length > 1) ? "s" : ""
             groups = " in group#{pl} \"#{groups}\""
           end
 
-          Bundler.ui.info "  * #{active_spec.name} (newest #{spec_version}, installed #{current_version}#{dependency_version})#{groups}".rstrip
+          spec_outdated_info = "#{active_spec.name} (newest #{spec_version}, installed #{current_version}#{dependency_version})"
+          if options[:parseable]
+            Bundler.ui.info spec_outdated_info.to_s.rstrip
+          else
+            Bundler.ui.info "  * #{spec_outdated_info}#{groups}".rstrip
+          end
+
           out_count += 1
         end
         Bundler.ui.debug "from #{active_spec.loaded_from}"
       end
 
       if out_count.zero?
-        Bundler.ui.info "Bundle up to date!\n"
+        Bundler.ui.info "Bundle up to date!\n" unless options[:parseable]
       else
         exit 1
       end

spec/commands/outdated_spec.rb

@@ -79,6 +79,43 @@
     end
   end
 
+  shared_examples_for "a minimal output is desired" do
+    context "and gems are outdated" do
+      before do
+        update_repo2 do
+          build_gem "activesupport", "3.0"
+          build_gem "weakling", "0.2"
+        end
+      end
+
+      it "outputs a sorted list of outdated gems with a more minimal format" do
+        minimal_output = "activesupport (newest 3.0, installed 2.3.5, requested = 2.3.5)\n" \
+                         "weakling (newest 0.2, installed 0.0.3, requested ~> 0.0.1)"
+        subject
+        expect(out).to eq(minimal_output)
+      end
+    end
+
+    context "and no gems are outdated" do
+      it "has empty output" do
+        subject
+        expect(out).to eq("")
+      end
+    end
+  end
+
+  describe "with --parseable option" do
+    subject { bundle "outdated --parseable" }
+
+    it_behaves_like "a minimal output is desired"
+  end
+
+  describe "with aliased --porcelain option" do
+    subject { bundle "outdated --porcelain" }
+
+    it_behaves_like "a minimal output is desired"
+  end
+
   describe "with specified gems" do
     it "returns list of outdated gems" do
       update_repo2 do