Add current_controller? helper method

Simplifies some of the "active tab" checks we're doing

app/helpers/application_helper.rb

@@ -1,6 +1,17 @@
 require 'digest/md5'
 module ApplicationHelper
 
+  # Check if a particular controller is the current one
+  #
+  # Examples
+  #
+  #   # On TreeController
+  #   current_controller?(:tree)    # => true
+  #   current_controller?(:commits) # => false
+  def current_controller?(name)
+    controller.controller_name == name.to_s.downcase
+  end
+
   def gravatar_icon(user_email = '', size = 40)
     if Gitlab.config.disable_gravatar? || user_email.blank?
       'no_avatar.png'

spec/helpers/application_helper_spec.rb

@@ -1,6 +1,20 @@
 require 'spec_helper'
 
 describe ApplicationHelper do
+  describe 'current_controller?' do
+    before do
+      controller.stub!(:controller_name).and_return('foo')
+    end
+
+    it "returns true when controller matches argument" do
+      current_controller?(:foo).should be_true
+    end
+
+    it "returns false when controller does not match argument" do
+      current_controller?(:bar).should_not be_true
+    end
+  end
+
   describe "gravatar_icon" do
     let(:user_email) { 'user@email.com' }