add spec to test skip_sidebar!

spec/unit/resource_controller/sidebars_spec.rb

@@ -0,0 +1,46 @@
+require 'spec_helper'
+
+describe ActiveAdmin::ResourceController::Sidebars do
+  let(:controller){ Admin::PostsController }
+
+  context 'without before_filter' do
+    before do
+      ActiveAdmin.register Post
+    end
+
+    subject { find_before_filter controller, :skip_sidebar! }
+
+    it { should set_skip_sidebar_to nil }
+  end
+
+  describe '#skip_sidebar!' do
+    before do
+      ActiveAdmin.register Post do
+        before_filter :skip_sidebar!
+      end
+    end
+
+    subject { find_before_filter controller, :skip_sidebar! }
+
+    it { should set_skip_sidebar_to true }
+  end
+
+  def find_before_filter(controller, filter)
+    #raise controller._process_action_callbacks.map(&:filter).inspect
+    controller._process_action_callbacks.detect { |f| f.raw_filter == filter.to_sym }
+  end
+
+  RSpec::Matchers.define :set_skip_sidebar_to do |expected|
+    match do |filter|
+      klass = filter && filter.klass || controller
+      object = klass.new
+      object.send filter.raw_filter if filter
+      @actual = object.instance_variable_get(:@skip_sidebar)
+      @actual == expected
+    end
+
+    failure_message_for_should do |filter|
+      message = "expected before_filter to set @skip_sidebar to '#{expected}', but was '#{@actual}'"
+    end
+  end
+end