Add missing pagination on the commit diff endpoint

changelogs/unreleased/17203-add-missing-pagination-commit-diff-endpoint.yml

+---
+  title: Add missing pagination on the commit diff endpoint
+  merge_request: 17203
+  author: Maxime Roussin-Bélanger
+  type: fixed

lib/api/commits.rb

@@ -97,13 +97,16 @@ module API
       end
       params do
         requires :sha, type: String, desc: 'A commit sha, or the name of a branch or tag'
+        use :pagination
       end
       get ':id/repository/commits/:sha/diff', requirements: API::COMMIT_ENDPOINT_REQUIREMENTS do
         commit = user_project.commit(params[:sha])
 
         not_found! 'Commit' unless commit
 
-        present commit.raw_diffs.to_a, with: Entities::Diff
+        raw_diffs = ::Kaminari.paginate_array(commit.raw_diffs.to_a)
+
+        present paginate(raw_diffs), with: Entities::Diff
       end
 
       desc "Get a commit's comments" do

spec/requests/api/commits_spec.rb

@@ -698,6 +698,7 @@ describe API::Commits do
         get api(route, current_user)
 
         expect(response).to have_gitlab_http_status(200)
+        expect(response).to include_pagination_headers
         expect(json_response.size).to be >= 1
         expect(json_response.first.keys).to include 'diff'
       end