brew cask list, when given args, list installed files

this mimics (and indeed steals code from) homebrew's behavior

refs #1417

lib/cask.rb

@@ -18,6 +18,7 @@ require 'cask/installer'
 require 'cask/link_checker'
 require 'cask/locations'
 require 'cask/pkg'
+require 'cask/pretty_listing'
 require 'cask/scopes'
 require 'cask/system_command'
 require 'cask/underscore_supporting_uri'

lib/cask/cli/list.rb

@@ -1,9 +1,32 @@
 class Cask::CLI::List
   def self.run(*arguments)
+    if arguments.any?
+      list_files(*arguments)
+    else
+      list_installed
+    end
+  end
+
+  def self.list_files(*cask_names)
+    cask_names.each do |cask_name|
+      begin
+        cask = Cask.load(cask_name)
+        if cask.installed?
+          Cask::PrettyListing.new(cask).print
+        else
+          opoo "#{cask} is not installed"
+        end
+      rescue CaskError => e
+        onoe e
+      end
+    end
+  end
+
+  def self.list_installed
     puts_columns Cask::CLI.nice_listing(Cask.installed)
   end
 
   def self.help
-    "lists installed casks"
+    "with no args, lists installed casks; given installed casks, lists installed files"
   end
 end

lib/cask/pretty_listing.rb

@@ -0,0 +1,12 @@
+require 'cmd/list' # for homebrew's ::PrettyListing
+
+class Cask::PrettyListing
+  attr_reader :cask
+  def initialize(cask)
+    @cask = cask
+  end
+
+  def print
+    ::PrettyListing.new(cask.destination_path)
+  end
+end

test/cask/cli/list_test.rb

@@ -1,10 +1,10 @@
 require 'test_helper'
 
 describe Cask::CLI::List do
-  it "lists the installed casks in a pretty fashion" do
-    shutup do
-      Cask::CLI::Install.run('local-transmission', 'local-caffeine')
-    end
+  it 'lists the installed casks in a pretty fashion' do
+    casks = %w[local-caffeine local-transmission].map { |c| Cask.load(c) }
+
+    casks.each { |c| TestHelper.install_without_artifacts(c) }
 
     lambda {
       Cask::CLI::List.run
@@ -13,4 +13,19 @@ describe Cask::CLI::List do
       local-transmission
     OUTPUT
   end
+
+  it 'given a set of installed casks, lists the installed files for those casks' do
+    casks = %w[local-caffeine local-transmission].map { |c| Cask.load(c) }
+
+    casks.each { |c| TestHelper.install_without_artifacts(c) }
+
+    caffeine, transmission = casks
+
+    lambda {
+      Cask::CLI::List.run('local-transmission', 'local-caffeine')
+    }.must_output <<-OUTPUT.gsub(/^ */, '')
+      #{transmission.destination_path}/Transmission.app/Contents/ (489 files)
+      #{caffeine.destination_path}/Caffeine.app/Contents/ (13 files)
+    OUTPUT
+  end
 end