Update closed MRs on push

In https://gitlab.com/gitlab-org/gitlab/-/merge_requests/29420,
we started filtering the branches that we update on push. It only
looks at branches with open MRs.

It caused a regression wherein closed MRs approvals weren't being
reset even when `reset_approvals_on_push` setting is set to `true`.

This updates the `MergeRequests::PushedBranchesService` to include
closed MRs with matching source branches as well.

app/services/merge_requests/pushed_branches_service.rb

@@ -9,7 +9,7 @@ module MergeRequests
     def execute
       return [] if branch_names.blank?
 
-      source_branches = project.source_of_merge_requests.opened
+      source_branches = project.source_of_merge_requests.open_and_closed
         .from_source_branches(branch_names).pluck(:source_branch)
 
       target_branches = project.merge_requests.opened

changelogs/unreleased/225579-reset-approvals-closed-mrs.yml

+---
+title: Update closed MRs on push
+merge_request: 37414
+author:
+type: fixed

spec/services/merge_requests/pushed_branches_service_spec.rb

@@ -8,19 +8,24 @@ RSpec.describe MergeRequests::PushedBranchesService do
 
   context 'when branches pushed' do
     let(:pushed_branches) do
-      %w(branch1 branch2 extra1 extra2 extra3).map do |branch|
+      %w(branch1 branch2 closed-branch1 closed-branch2 extra1 extra2).map do |branch|
         { ref: "refs/heads/#{branch}" }
       end
     end
 
-    it 'returns only branches which have a merge request' do
+    it 'returns only branches which have a open and closed merge request' do
       create(:merge_request, source_branch: 'branch1', source_project: project)
       create(:merge_request, source_branch: 'branch2', source_project: project)
       create(:merge_request, target_branch: 'branch2', source_project: project)
-      create(:merge_request, :closed, target_branch: 'extra1', source_project: project)
-      create(:merge_request, source_branch: 'extra2')
-
-      expect(service.execute).to contain_exactly('branch1', 'branch2')
+      create(:merge_request, :closed, target_branch: 'closed-branch1', source_project: project)
+      create(:merge_request, :closed, source_branch: 'closed-branch2', source_project: project)
+      create(:merge_request, source_branch: 'extra1')
+
+      expect(service.execute).to contain_exactly(
+        'branch1',
+        'branch2',
+        'closed-branch2'
+      )
     end
   end