Add abstract base class for core CI status

lib/gitlab/ci/status/core/base.rb

+module Gitlab::Ci
+  module Status
+    module Core
+      # Base abstract class fore core status
+      #
+      class Base
+        def initialize(subject)
+          @subject = subject
+        end
+
+        def icon
+          raise NotImplementedError
+        end
+
+        def label
+          raise NotImplementedError
+        end
+
+        def has_details?
+          raise NotImplementedError
+        end
+
+        def details_path
+          raise NotImplementedError
+        end
+
+        def has_action?
+          raise NotImplementedError
+        end
+
+        def action_icon
+          raise NotImplementedError
+        end
+
+        def action_path
+          raise NotImplementedError
+        end
+      end
+    end
+  end
+end

lib/gitlab/ci/status/core/success.rb

 module Gitlab::Ci
   module Status
     module Core
-      class Success
+      class Success < Core::Base
         def label
           'passed'
         end

spec/lib/gitlab/ci/status/core/success_spec.rb

 require 'spec_helper'
 
 describe Gitlab::Ci::Status::Core::Success do
+  subject { described_class.new(double('subject')) }
+
   describe '#label' do
     it { expect(subject.label).to eq 'passed' }
   end