Extract abilities checking module from ability model

app/models/ability.rb

 class Ability
-  module Allowable
-    def can?(user, action, subject)
-      Ability.allowed?(user, action, subject)
-    end
-  end
-
   class << self
     # Given a list of users and a project this method returns the users that can
     # read the given project.

lib/gitlab/allowable.rb

+module Gitlab
+  module Allowable
+    def can?(user, action, subject)
+      Ability.allowed?(user, action, subject)
+    end
+  end
+end
+

lib/gitlab/ci/status/core.rb

@@ -5,7 +5,7 @@ module Gitlab
       #
       class Core
         include Gitlab::Routing.url_helpers
-        include Ability::Allowable
+        include Gitlab::Allowable
 
         attr_reader :subject, :user
 

spec/lib/gitlab/allowable_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Allowable do
+  subject do
+    Class.new.include(described_class).new
+  end
+
+  describe '#can?' do
+    let(:user) { create(:user) }
+
+    context 'when user is allowed to do something' do
+      let(:project) { create(:empty_project, :public) }
+
+      it 'reports correct ability to perform action' do
+        expect(subject.can?(user, :read_project, project)).to be true
+      end
+    end
+
+    context 'when user is not allowed to do something' do
+      let(:project) { create(:empty_project, :private) }
+
+      it 'reports correct ability to perform action' do
+        expect(subject.can?(user, :read_project, project)).to be false
+      end
+    end
+  end
+end