unit tests for extensions mechanism, and a bit more robustness

git-svn-id: http://svn.rubyonrails.org/rails/tools/capistrano@6438 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

lib/capistrano/extensions.rb

@@ -1,5 +1,5 @@
 module Capistrano
-  class ExtensionProxy
+  class ExtensionProxy #:nodoc:
     def initialize(config, mod)
       @config = config
       extend(mod)
@@ -10,11 +10,25 @@ module Capistrano
     end
   end
 
+  # Holds the set of registered plugins, keyed by name (where the name is a
+  # symbol).
   EXTENSIONS = {}
 
+  # Register the given module as a plugin with the given name. It will henceforth
+  # be available via a proxy object on Configuration instances, accessible by
+  # a method with the given name.
   def self.plugin(name, mod)
+    name = name.to_sym
     return false if EXTENSIONS.has_key?(name)
 
+    methods = Capistrano::Configuration.public_instance_methods +
+      Capistrano::Configuration.protected_instance_methods +
+      Capistrano::Configuration.private_instance_methods
+
+    if methods.include?(name.to_s)
+      raise Capistrano::Error, "registering a plugin named `#{name}' would shadow a method on Capistrano::Configuration with the same name"
+    end
+
     Capistrano::Configuration.class_eval <<-STR, __FILE__, __LINE__+1
       def #{name}
         @__#{name}_proxy ||= Capistrano::ExtensionProxy.new(self, Capistrano::EXTENSIONS[#{name.inspect}])
@@ -25,7 +39,9 @@ module Capistrano
     return true
   end
 
+  # Unregister the plugin with the given name.
   def self.remove_plugin(name)
+    name = name.to_sym
     if EXTENSIONS.delete(name)
       Capistrano::Configuration.send(:remove_method, name)
       return true
@@ -34,7 +50,7 @@ module Capistrano
     return false
   end
 
-  def self.configuration(*args)
+  def self.configuration(*args) #:nodoc:
     warn "[DEPRECATION] Capistrano.configuration is deprecated. Use Capistrano::Configuration.instance instead"
     Capistrano::Configuration.instance(*args)
   end

test/extensions_test.rb

@@ -0,0 +1,69 @@
+require "#{File.dirname(__FILE__)}/utils"
+require 'capistrano'
+
+class ExtensionsTest < Test::Unit::TestCase
+  module CustomExtension
+    def do_something(command)
+      run(command)
+    end
+  end
+
+  def setup
+    @config = Capistrano::Configuration.new
+  end
+
+  def teardown
+    Capistrano::EXTENSIONS.keys.each { |e| Capistrano.remove_plugin(e) }
+  end
+
+  def test_register_plugin_should_add_instance_method_on_configuration_and_return_true
+    assert !@config.respond_to?(:custom_stuff)
+    assert Capistrano.plugin(:custom_stuff, CustomExtension)
+    assert @config.respond_to?(:custom_stuff)
+  end
+
+  def test_register_plugin_that_already_exists_should_return_false
+    assert Capistrano.plugin(:custom_stuff, CustomExtension)
+    assert !Capistrano.plugin(:custom_stuff, CustomExtension)
+  end
+
+  def test_register_plugin_with_public_method_name_should_fail
+    method = Capistrano::Configuration.public_instance_methods.first
+    assert_not_nil method, "need a public instance method for testing"
+    assert_raises(Capistrano::Error) { Capistrano.plugin(method, CustomExtension) }
+  end
+
+  def test_register_plugin_with_protected_method_name_should_fail
+    method = Capistrano::Configuration.protected_instance_methods.first
+    assert_not_nil method, "need a protected instance method for testing"
+    assert_raises(Capistrano::Error) { Capistrano.plugin(method, CustomExtension) }
+  end
+
+  def test_register_plugin_with_private_method_name_should_fail
+    method = Capistrano::Configuration.private_instance_methods.first
+    assert_not_nil method, "need a private instance method for testing"
+    assert_raises(Capistrano::Error) { Capistrano.plugin(method, CustomExtension) }
+  end
+
+  def test_unregister_plugin_that_does_not_exist_should_return_false
+    assert !Capistrano.remove_plugin(:custom_stuff)
+  end
+
+  def test_unregister_plugin_should_remove_method_and_return_true
+    assert Capistrano.plugin(:custom_stuff, CustomExtension)
+    assert @config.respond_to?(:custom_stuff)
+    assert Capistrano.remove_plugin(:custom_stuff)
+    assert !@config.respond_to?(:custom_stuff)
+  end
+
+  def test_registered_plugin_proxy_should_return_proxy_object
+    Capistrano.plugin(:custom_stuff, CustomExtension)
+    assert_instance_of Capistrano::ExtensionProxy, @config.custom_stuff
+  end
+
+  def test_proxy_object_should_delegate_to_configuration
+    Capistrano.plugin(:custom_stuff, CustomExtension)
+    @config.expects(:run).with("hello")
+    @config.custom_stuff.do_something("hello")
+  end
+end