Add rake task for running plugin tests.

config/application.rb

@@ -157,7 +157,7 @@ module Discourse
     config.active_record.whitelist_attributes = false unless rails4?
 
     require 'auth'
-    Discourse.activate_plugins! unless Rails.env.test?
+    Discourse.activate_plugins! unless Rails.env.test? and ENV['LOAD_PLUGINS'] != "true"
 
     config.after_initialize do
       # So open id logs somewhere sane

lib/tasks/plugin.rake

@@ -42,3 +42,15 @@ task 'plugin:update', :plugin do |t, args|
   update_status = system('git --git-dir "' + plugin_path + '/.git" --work-tree "' + plugin_path + '" pull')
   abort('Unable to pull latest version of plugin') unless update_status
 end
+
+desc 'run plugin specs'
+task 'plugin:spec', :plugin do |t, args|
+  args.with_defaults(plugin: "**")
+  ruby = `which ruby`.strip
+  files = Dir.glob("./plugins/#{args[:plugin]}/spec/*.rb")
+  if files.length > 0
+    sh "LOAD_PLUGINS=true #{ruby} -S rspec #{files.join(' ')}"
+  else
+    abort "No specs found."
+  end
+end