Add 'list' command to CLI

* This will list all the users you've added to your keys file with this
  gem.

Author: iamvery

lib/github/auth/cli.rb

@@ -3,7 +3,7 @@ module Github::Auth
   class CLI
     attr_reader :command, :usernames
 
-    COMMANDS = %w(add remove)
+    COMMANDS = %w(add remove list)
 
     def initialize(argv)
       @command   = argv.shift
@@ -42,6 +42,10 @@ def remove
         "Removing #{keys.count} key(s) from '#{keys_file.path}'"
     end
 
+    def list
+      puts "Added users: #{keys_file.github_users.join(', ')}"
+    end
+
     def on_keys_file(action, message)
       puts message
       rescue_keys_file_errors { keys_file.send action, keys }

spec/acceptance/github/auth/cli_spec.rb

@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'support/capture_stdout'
 require 'support/mock_github_server'
 require 'github/auth'
 
@@ -32,5 +33,15 @@ def cli(argv)
 
       keys_file.unlink
     end
+
+    it 'lists users from the keys file' do
+      cli(%w(add chrishunt)).execute
+
+      output = capture_stdout do
+        cli(%w(list)).execute
+      end
+
+      expect(output).to include('chrishunt')
+    end
   end
 end