Merge branch 'oldrev-in-update-hooks' into 'master'

webhooks: include old revision in MR update events

## What does this MR do?

Includes the old revision for an MR in webhooks.

## Are there points in the code the reviewer needs to double check?

The docs do not give an example `update` hook; should I add one?

## Why was this MR needed?

In order to keep web hook listeners stateless, it helps to include the previous revision of the MR in the hook so that it does not need to remember the last revision (which may also be wrong in case of missed or out-of-order events due to previous errors).

## What are the relevant issue numbers?

N/A

## Screenshots (if relevant)

N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5535

CHANGELOG

@@ -20,6 +20,7 @@ v 8.11.0 (unreleased)
   - Optimize checking if a user has read access to a list of issues !5370
   - Nokogiri's various parsing methods are now instrumented
   - Add a way to send an email and create an issue based on private personal token. Find the email address from issues page. !3363
+  - Include old revision in merge request update hooks (Ben Boeckel)
   - Add build event color in HipChat messages (David Eisner)
   - Make fork counter always clickable. !5463 (winniehell)
   - All created issues, API or WebUI, can be submitted to Akismet for spam check !5333

app/services/merge_requests/base_service.rb

@@ -17,16 +17,19 @@ module MergeRequests
       end
     end
 
-    def hook_data(merge_request, action)
+    def hook_data(merge_request, action, oldrev = nil)
       hook_data = merge_request.to_hook_data(current_user)
       hook_data[:object_attributes][:url] = Gitlab::UrlBuilder.build(merge_request)
       hook_data[:object_attributes][:action] = action
+      if oldrev && !Gitlab::Git.blank_ref?(oldrev)
+        hook_data[:object_attributes][:oldrev] = oldrev
+      end
       hook_data
     end
 
-    def execute_hooks(merge_request, action = 'open')
+    def execute_hooks(merge_request, action = 'open', oldrev = nil)
       if merge_request.project
-        merge_data = hook_data(merge_request, action)
+        merge_data = hook_data(merge_request, action, oldrev)
         merge_request.project.execute_hooks(merge_data, :merge_request_hooks)
         merge_request.project.execute_services(merge_data, :merge_request_hooks)
       end

app/services/merge_requests/refresh_service.rb

@@ -137,7 +137,7 @@ module MergeRequests
     # Call merge request webhook with update branches
     def execute_mr_web_hooks
       merge_requests_for_source_branch.each do |merge_request|
-        execute_hooks(merge_request, 'update')
+        execute_hooks(merge_request, 'update', @oldrev)
       end
     end
 

spec/services/merge_requests/refresh_service_spec.rb

@@ -57,7 +57,7 @@ describe MergeRequests::RefreshService, services: true do
 
       it 'should execute hooks with update action' do
         expect(refresh_service).to have_received(:execute_hooks).
-          with(@merge_request, 'update')
+          with(@merge_request, 'update', @oldrev)
       end
 
       it { expect(@merge_request.notes).not_to be_empty }
@@ -113,7 +113,7 @@ describe MergeRequests::RefreshService, services: true do
 
       it 'should execute hooks with update action' do
         expect(refresh_service).to have_received(:execute_hooks).
-          with(@fork_merge_request, 'update')
+          with(@fork_merge_request, 'update', @oldrev)
       end
 
       it { expect(@merge_request.notes).to be_empty }
@@ -158,7 +158,7 @@ describe MergeRequests::RefreshService, services: true do
 
       it 'refreshes the merge request' do
         expect(refresh_service).to receive(:execute_hooks).
-                                       with(@fork_merge_request, 'update')
+                                       with(@fork_merge_request, 'update', Gitlab::Git::BLANK_SHA)
         allow_any_instance_of(Repository).to receive(:merge_base).and_return(@oldrev)
 
         refresh_service.execute(Gitlab::Git::BLANK_SHA, @newrev, 'refs/heads/master')