Merge branch 'rails-rake-proxy'

4 files changed, 63 insertions, 11 deletions

diff --git a/guides/source/initialization.md b/guides/source/initialization.md
index ebe1cb206a..7bf7eebb62 100644
--- a/guides/source/initialization.md
+++ b/guides/source/initialization.md
@@ -139,7 +139,8 @@ aliases = {
   "c"  => "console",
   "s"  => "server",
   "db" => "dbconsole",
-  "r"  => "runner"
+  "r"  => "runner",
+  "t"  => "test"
 }
 
 command = ARGV.shift
@@ -158,19 +159,20 @@ defined here to find the matching command.
 
 ### `rails/commands/command_tasks.rb`
 
-When one types an incorrect rails command, the `run_command` is responsible for
-throwing an error message. If the command is valid, a method of the same name
-is called.
+When one types a valid Rails command, `run_command!` a method of the same name
+is called. If Rails doesn't recognize the command, it tries to run a Rake task
+of the same name.
 
 ```ruby
 COMMAND_WHITELIST = %w(plugin generate destroy console server dbconsole application runner new version help)
 
 def run_command!(command)
   command = parse_command(command)
+
   if COMMAND_WHITELIST.include?(command)
     send(command)
   else
-    write_error_message(command)
+    run_rake_task(command)
   end
 end
 ```
diff --git a/railties/lib/rails/commands.rb b/railties/lib/rails/commands.rb
index b9c4e02ca0..7627fcf5a0 100644
--- a/railties/lib/rails/commands.rb
+++ b/railties/lib/rails/commands.rb
@@ -7,7 +7,7 @@ aliases = {
   "s"  => "server",
   "db" => "dbconsole",
   "r"  => "runner",
-  "t"  => "test",
+  "t"  => "test"
 }
 
 command = ARGV.shift
diff --git a/railties/lib/rails/commands/commands_tasks.rb b/railties/lib/rails/commands/commands_tasks.rb
index 7e6b49e2a3..da3b9452d5 100644
--- a/railties/lib/rails/commands/commands_tasks.rb
+++ b/railties/lib/rails/commands/commands_tasks.rb
@@ -1,3 +1,5 @@
+require 'rails/commands/rake_proxy'
+
 module Rails
   # This is a class which takes in a rails command and initiates the appropriate
   # initiation sequence.
@@ -5,6 +7,8 @@ module Rails
   # Warning: This class mutates ARGV because some commands require manipulating
   # it before they are run.
   class CommandsTasks # :nodoc:
+    include Rails::RakeProxy
+
     attr_reader :argv
 
     HELP_MESSAGE = <<-EOT
@@ -20,14 +24,18 @@ The most common rails commands are:
  new         Create a new Rails application. "rails new my_app" creates a
              new application called MyApp in "./my_app"
 
-In addition to those, there are:
- destroy      Undo code generated with "generate" (short-cut alias: "d")
- plugin new   Generates skeleton for developing a Rails plugin
- runner       Run a piece of code in the application environment (short-cut alias: "r")
-
 All commands can be run with -h (or --help) for more information.
+
+In addition to those commands, there are:
 EOT
 
+    ADDITIONAL_COMMANDS = [
+      [ 'destroy', 'Undo code generated with "generate" (short-cut alias: "d")' ],
+      [ 'plugin new', 'Generates skeleton for developing a Rails plugin' ],
+      [ 'runner',
+        'Run a piece of code in the application environment (short-cut alias: "r")' ]
+    ]
+
     COMMAND_WHITELIST = %w(plugin generate destroy console server dbconsole runner new version help test)
 
     def initialize(argv)
@@ -39,6 +47,8 @@ EOT
 
       if COMMAND_WHITELIST.include?(command)
         send(command)
+      else
+        run_rake_task(command)
       end
     end
 
@@ -109,6 +119,7 @@ EOT
 
     def help
       write_help_message
+      write_commands ADDITIONAL_COMMANDS + formatted_rake_tasks
     end
 
     private
@@ -150,6 +161,11 @@ EOT
         puts HELP_MESSAGE
       end
 
+      def write_commands(commands)
+        width = commands.map { |name, _| name.size }.max || 10
+        commands.each { |command| printf(" %-#{width}s   %s\n", *command) }
+      end
+
       def parse_command(command)
         case command
         when '--version', '-v'
diff --git a/railties/lib/rails/commands/rake_proxy.rb b/railties/lib/rails/commands/rake_proxy.rb
new file mode 100644
index 0000000000..f7d5df6b2f
--- /dev/null
+++ b/railties/lib/rails/commands/rake_proxy.rb
@@ -0,0 +1,34 @@
+require 'rake'
+require 'active_support'
+
+module Rails
+  module RakeProxy #:nodoc:
+    private
+      def run_rake_task(command)
+        ARGV.unshift(command) # Prepend the command, so Rake knows how to run it.
+
+        Rake.application.standard_exception_handling do
+          Rake.application.init('rails')
+          Rake.application.load_rakefile
+          Rake.application.top_level
+        end
+      end
+
+      def rake_tasks
+        return @rake_tasks if defined?(@rake_tasks)
+
+        ActiveSupport::Deprecation.silence do
+          require_application_and_environment!
+        end
+
+        Rake::TaskManager.record_task_metadata = true
+        Rake.application.instance_variable_set(:@name, 'rails')
+        Rails.application.load_tasks
+        @rake_tasks = Rake.application.tasks.select(&:comment)
+      end
+
+      def formatted_rake_tasks
+        rake_tasks.map { |t| [ t.name_with_args, t.comment ] }
+      end
+  end
+end