Factor '0' * 40 blank ref constants

app/services/git_push_service.rb

@@ -160,19 +160,19 @@ class GitPushService
     ref_parts = ref.split('/')
 
     # Return if this is not a push to a branch (e.g. new commits)
-    ref_parts[1] =~ /heads/ && oldrev != "0000000000000000000000000000000000000000"
+    ref_parts[1] =~ /heads/ && oldrev != Gitlab::Git::BLANK_SHA
   end
 
   def push_to_new_branch?(ref, oldrev)
     ref_parts = ref.split('/')
 
-    ref_parts[1] =~ /heads/ && oldrev == "0000000000000000000000000000000000000000"
+    ref_parts[1] =~ /heads/ && oldrev == Gitlab::Git::BLANK_SHA
   end
 
   def push_remove_branch?(ref, newrev)
     ref_parts = ref.split('/')
 
-    ref_parts[1] =~ /heads/ && newrev == "0000000000000000000000000000000000000000"
+    ref_parts[1] =~ /heads/ && newrev == Gitlab::Git::BLANK_SHA
   end
 
   def push_to_branch?(ref)

features/steps/dashboard/event_filters.rb

@@ -29,7 +29,7 @@ class Spinach::Features::EventFilters < Spinach::FeatureSteps
 
   step 'this project has push event' do
     data = {
-      before: "0000000000000000000000000000000000000000",
+      before: Gitlab::Git::BLANK_SHA,
       after: "0220c11b9a3e6c69dc8fd35321254ca9a7b98f7e",
       ref: "refs/heads/new_design",
       user_id: @user.id,

features/steps/shared/project.rb

@@ -32,7 +32,7 @@ module SharedProject
     @project = Project.find_by(name: "Shop")
 
     data = {
-      before: "0000000000000000000000000000000000000000",
+      before: Gitlab::Git::BLANK_SHA,
       after: "6d394385cf567f80a8fd85055db1ab4c5295806f",
       ref: "refs/heads/fix",
       user_id: @user.id,

lib/gitlab/git.rb

+module Gitlab
+  module Git
+    BLANK_SHA = '0' * 40
+  end
+end

spec/models/event_spec.rb

@@ -36,7 +36,7 @@ describe Event do
       @user = project.owner
 
       data = {
-        before: "0000000000000000000000000000000000000000",
+        before: Gitlab::Git::BLANK_SHA,
         after: "0220c11b9a3e6c69dc8fd35321254ca9a7b98f7e",
         ref: "refs/heads/master",
         user_id: @user.id,

spec/services/git_push_service_spec.rb

@@ -8,7 +8,7 @@ describe GitPushService do
   let (:service) { GitPushService.new }
 
   before do
-    @blankrev = '0000000000000000000000000000000000000000'
+    @blankrev = Gitlab::Git::BLANK_SHA
     @oldrev = sample_commit.parent_id
     @newrev = sample_commit.id
     @ref = 'refs/heads/master'