Add a spec for the new plugins controller

spec/controllers/admin/plugins_controller_spec.rb

@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe Admin::PluginsController do
+
+  it "is a subclass of AdminController" do
+    expect(Admin::PluginsController < Admin::AdminController).to eq(true)
+  end
+
+  context "while logged in as an admin" do
+    let!(:admin) { log_in(:admin) }
+
+    it 'should return JSON' do
+      xhr :get, :index
+      response.should be_success
+      ::JSON.parse(response.body).has_key?('plugins').should == true
+    end
+  end
+
+end
+