Add class level `run` to Rails command.

The class level version is responsible for changing a task name to
command name, then finding a command and run it if there is one.

The instance level `run` then makes sure arguments have been parsed
into `@options` and runs the command by sending it.

`Rails::Commands::Command.run` returns true to make it work within
`Rails::CommandsTask`, but won't in the future when it handles
all option parsing.

railties/lib/rails/commands/command.rb

@@ -10,17 +10,20 @@ def initialize(argv = [])
         @options = {}
       end
 
-      def run(task_name)
-        command_name = self.class.command_name_for(task_name)
+      def self.run(task_name, argv)
+        command_name = command_name_for(task_name)
 
+        if command = command_for(command_name)
+          command.new(argv).run(command_name)
+          true # Indicate command was found and run.
+        end
+      end
+
+      def run(command_name)
         parse_options_for(command_name)
         @option_parser.parse! @argv
 
-        if command = command_for(command_name)
-          command.public_send(command_name)
-        else
-          puts @option_parser
-        end
+        public_send(command_name)
       end
 
       def self.options_for(command_name, &options_to_parse)
@@ -31,11 +34,6 @@ def self.set_banner(command_name, banner)
         options_for(command_name) { |opts, _| opts.banner = banner }
       end
 
-      def exists?(task_name) # :nodoc:
-        command_name = self.class.command_name_for(task_name)
-        !command_for(command_name).nil?
-      end
-
       private
         @@commands = []
         @@command_options = {}
@@ -61,14 +59,10 @@ def self.command_name_for(task_name)
           task_name.gsub(':', '_').to_sym
         end
 
-        def command_for(command_name)
-          klass = @@commands.find do |command|
+        def self.command_for(command_name)
+          @@commands.find do |command|
             command.public_instance_methods.include?(command_name)
           end
-
-          if klass
-            klass.new(@argv)
-          end
         end
     end
   end

railties/lib/rails/commands/commands_tasks.rb

@@ -32,15 +32,14 @@ class CommandsTasks # :nodoc:
 
     def initialize(argv)
       @argv = argv
-      @rails_command = Rails::Commands::Command.new(argv)
     end
 
     def run_command!(command)
       command = parse_command(command)
 
-      if @rails_command.exists?(command)
-        @rails_command.run(command)
-      elsif COMMAND_WHITELIST.include?(command)
+      run_with_command = Rails::Commands::Command.run(command, argv)
+
+      if !run_with_command && COMMAND_WHITELIST.include?(command)
         send(command)
       else
         write_error_message(command)